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					SEVERITY AND IMPACT OF REWORK, A CASE STUDY OF A
 RESIDENTIAL COMMERCIAL TOWER PROJECT IN THE
              EASTERN PROVINCE-KSA




                    By
         MOATAZ AHMED FAROUK WASFY


          An Engineering Report Presented to the
 DEPARTMENT OF CONSTRUCTION ENGINEERING AND
                MANAGEMENT




               In Partial Fulfillment of the
              Requirements for the degree of

             MASTER OF ENGINEERING
                            In

   CONSTRUCTION ENGINEERING & MANAGEMENT



 KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
             DHAHRAN, SAUDI ARABIA



                      JUNE, 2010
       KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
             COLLEGE OF ENVIRONMENTAL DESIGN
   DEPARTMENT OF CONSTRUCTION ENGINEERING & MANAGEMENT




This Master of Engineering Report, written by MOATAZ AHMED FAROUK
WASFY under the direction of his Report Advisor and approved by his Report
Advisor and Reader has been presented to and accepted by the Department of
Construction Engineering & Management in partial fulfillment of the requirements for
the degree of MASTER OF ENGINEERING IN CONSTRUCTION ENGINEERING
AND MANAGEMENT.




____________________________

Dr. Soliman Almohawis
(Report Advisor)




__________
Date




                                         I
                           ACKNOWLEDGEMENT



All the praises and thanks be to Allah, the Lord of Alamin and peace be upon the
Master of the Messengers Muhammad (PBUH).

I would like to extend my sincere thanks and appreciation to all who contributed to
this work.

My special thanks and gratitude to Dr. Soliman Almohawis for his sincere effort,
guidance, and the precious time that he offered me.

Thanks to Dr. Sadi Assaf for his precious time.

I dedicate and reward this work to the spirit of my Father, God bless his soul, my
mother wishing her good health and long life.
Finally, I would like to extend my thanks and appreciation to my wife, who had a
major impact in encouraging me to complete this report.

I pray to God that this work is a legacy to my children and guide them to follow the
path of knowledge in the hope of progress and prosperity.




                                           II
                                   ABSTRACT


FULL NAME OF STUDENT             : MOATAZ AHMED FAROUK WASFY

TITLE OF STUDY                   : SEVERITY AND IMPACT OF REWORK,

                                    A CASE STUDY ON A RESIDENTIAL COMMERCIAL

                                    TOWER PROJECT IN THE EASTERN PROVINCE-KSA

MAJOR                            : CONSTRUCTION ENGINEERING AND MANAGEMENT

DATE OF DEGREE                   : JUNE, 2010




This study was conducted to investigate rework severity and its impact on a case study
project of a residential commercial tower in the Eastern Province – Saudi Arabia.
        Interviews were held with ten main participants of the project to investigate
the frequency of rework on different work categories, and to disclose the main causes
that contributed to rework, the frequency of each rework cause, the impact of rework
on project’s cost and time as well as the impact of rework on client and contractor
satisfaction.
        Causes lead to rework in the case study project, such as incompetent
supervision, insufficient supervision, poor workmanship, improper subcontractor
selection, improper work protection, and improper work sequencing.
        Rework increased the cost of the different work categories between 2% to
30%. Rework caused delays in the different work categories resulting in the increase
of their original durations 10% to 77%. Additionally, rework caused clients' and
contractors' dissatisfaction.




                                          III
                                          ‫ملخـص الرســـالة‬



               ‫معــــزـض أحـمــــذ فـــــــــبسوق وصـــــــفً.‬    ‫:‬                 ‫االســـــــــــــــــــــم‬


  ‫شذح وأثش إعبدح انعمم، دساسخ حبنخ نمششوع ثشج سكنً‬                ‫:‬                 ‫عنــوان الرســــالة‬

      ‫رجبسي ثبنمنطمخ انششلٍخ- انممهكخ انعشثٍخ انسعودٌخ.‬

                                       ‫ىنذسخ وإداسح انزشٍٍذ.‬      ‫:‬                 ‫التخصــــــــــــــص‬

                                              ‫ٌونٍو 0102 و.‬       ‫:‬                 ‫تاريخ التخــــــــرج‬




‫سكنً رجبسي‬                                                                            ‫ال‬
                ‫أجشٌذ ىزه دساسخ – كذساسخ حبنخ - نهزحمٍك فً شذح ركشاس انعمم وأثشه عهى مششوع ثشج‬
                                                                                                  ‫ة‬
                                                        ‫انمنطمخ انششلٍخ من انممهكخ انعشثٍخ انسعودٌخ.‬
   ‫ولذ أجشٌذ ممبثالد مع عششح من انمشبسكٍن انشئٍسٍٍن ثبنمششوع ورنك نهزحمٍك فً ورٍشح إعبدح انعمم عهى‬
                                                                                    ‫ال‬
  ‫فئبد األعمبل مخزهفخ ، وانكشف عن األسجبة انشئٍسٍخ انزً سبىمذ فً إعبدح انعمم ، ومذي ركشاس كم سجت‬
    ‫فً إعبدح انعمم ، وأثش إعبدح انعمم عهى ركهفخ انمششوع ومذح انمششوع وكزنك رأثٍش إعبدح انعمم عهً مذي‬
                                                                             ‫سضبء انمبنك و انممبول.‬

              ‫ال‬
‫سبىمذ أسجبة كثٍشح إلعبدح انعمم نمششوع حبنخ دساسٍخ و من رهك االسجبة اإلششاف غٍش كفء، واإلششاف‬
         ‫ل‬                  ‫ال‬
‫ي انجبطن ، و حمبٌخ انغٍش منبسجخ ألعمبل ، و‬‫انغٍش كبف ،وانمصنعٍبد انشدٌئخ، ، واإلخزٍبس انغٍش منبست نممبول‬
                                                         ‫رسهسم انعمم انغٍش منبست ،و اننمص فً انزنسٍك.‬


  ‫نمذ أثشد إعبدح انعمم فً مششوع انحبنخ انذساسٍخ فً ولذ وركهفخ انمششوع. فمذ رسججذ فً صٌبدح انزكهفخ اننبرجخ‬
 ‫عن إعبدح انعمم فً نست صٌبدح رزشواح ثٍن 2% إنً 03% نفئبد انعمم انمخزهفخ. فً حٍن رسججذ إعبدح انعمم‬
‫فً انزأخٍش ثنست رزفبود من فئخ عمم إنً أخشي ولذ رشاوحذ ثٍن 01% إنً 07% رأخٍش. إ ضبفخ إنً رنك فمذ‬
                                                          ‫رسجت إعبدح انعمم فً عذو سضبء انمبنك وانممبول.‬




                                                   ‫‪IV‬‬
                     TABLE OF CONTENTS


                                                                          Page

ACKNOWLEDGEMENT……………………………………………………...................                     II

ABSTRACT………………………………………………………………………..............                         III

‫.....................................…………………………………………………………ملخص الرسالة‬   IV

TABLE OF CONTENTS…………………………………………………………….........                          V

LIST OF FIGURES ………………………………………………..…………...................                X

LIST OF TABLES ……………………………………………..…………….....................              XI

CHAPTER ONE……………………………………………..…………….…....................                  1

1   INTRODUCTION……………………….……………………….…….…….............                     1

        1.1   RESEARCH OBJECTIVES……………………………………………                         4

        1.2   STATEMENT OF THE PROBLEM…………………………………..                      5

        1.3   SIGNIFICANCE OF THE STUDY…………………………………….                     5

        1.4   SCOPE AND LIMITATIONS………………………………………….                       6

CHAPTER TWO…………………………………...…………………………...................                   8

2   LITERATURE REVIEW………………………………..………………………….                             8

        2.1   REWORK DEFINITION………………………………………………..                        8

        2.2   REWORK MODELS…………………………………………………….                           8

               2.2.1 CONCEPTUAL MODEL OF REWORK………………………                   8

                        2.2.1.1 PROJECT CHARATERISTICS……………………             9

                        2.2.1.1 ORGANAIZATIONAL MANAGEMENT                10

                        PRACTICES………………………………………………………

                        2.2.1.3 PROJECT MANAGEMENT PRACTICES………..         13



                                 V
                       2.2.1.4 PRODUCTIVITY………………………………….             15

                       2.2.1.5 PROJECT PERFORMANCE……………………..          16

             2.2.2   CLASSIFICATION MODEL OF REWORK CAUSES………         20

                       2.2.2.1   LEADERSHIP AND COMMUNICATIONS……...   20

                       2.2.2.2 HUMAN RESOURCE CAPABILITIES…………...     23

                       2.2.2.3 ENGINEERING AND REVIEW…………………..        24

                       2.2.2.4 CONSTRUCTION PLANNING AND              25

                       SCHEDULING…………………………………………….

                       2.2.2.5 MATERIALS AND EQUIPMENT SUPPLY……….     26

             2.2.3 A PROPOSED REWORK MODEL…………………………….                27

                      2.2.3.1 DIRECT REWORK CAUSES………………………           27

                      2.2.3.2 INDIRECT REWORK CAUSES……………………          29

      2.3   REWORK MINIMIZATION…………………………………………...                    30

CHAPTER THREE……………………………………………………………………….                             35

3   RESEARCH METHODOLOGY…………………………………………………...                        35

      3.1   CASE STUDY……………………………………………………………                         35

      3.2   DATA COLLECTION…………………………………………………..                      36

CHAPTER FOUR…………………………………………………………………………                              39

4   RESULTS AND DISCUSSIONS……………………………………………………                       39

      4.1   SEVERITY OF REWOK………………………………………………..                     39

             4.1.1   DISCUSSION OF SEVERITY OF REWOK……………………          43

      4.2   REWORK CAUSES…………………………………………………….                        49

             4.2.1   AVERAGE FREQUENCY OF REWORK CAUSES ON WORK       50

             CATEGORIES ………………………………………………………….



                                  VI
4.2.1.1   REWORK CAUSES AFFECTING MANY WORK           52

CATEGORIES……………………………………………….

           4.2.1.1.1   INSUFFICIENT SUPERVISION…..    52

                        4.2.1.1.1.1   DISCUSSION OF   55

                        INSUFFICIENT SUPERVISION….

           4.2.1.1.2   INCOMPETENT SUPERVISION…...    57

                        4.2.1.1.2.1   DISCUSSION OF   57

                        INCOMPETENT SUPERVISION…

           4.2.1.1.3   POOR WORKMANSHIP…………...        62

                        4.2.1.1.3.1   DISCUSSION OF   65

                        POOR WORKMANSHIP………….

4.2.1.2   REWORK CAUSES AFFECTED FEW WORK             66

CATEGORIES……………………………………………….

           4.2.1.2.1   IMPROPER SUBCONTRACTOR         67

           SELECTION…………………………………….

                        4.2.1.2.1.1   DISCUSSION OF   67

                        IMPROPER SUBCONTRACTOR

                        SELECTION………………………….

           4.2.1.2.2   IMPROPER WORK PROTECTION       70

                        4.2.1.2.2.1   DISCUSSION OF   70

                        IMPROPER WORK PROTECTION

           4.2.1.2.3   LACK OF COORDINATION……….       71

                        4.2.2.2.3.1   DISCUSSION OF   72

                        LACK OF COORDINATION……..

           4.2.1.2.4   WRONG MATERIAL………………           73


            VII
                             4.2.1.2.4.1   DISCUSSION OF   73

                             WRONG MATERIAL……………...

                4.2.1.2.5   DEFECTIVE MATERIAL…………...      75

                             4.2.1.2.5.1   DISCUSSION OF   75

                             DEFECTIVE MATERIAL…………

                4.2.1.2.6   DEVIATIONS FROM DRAWINGS….     76

                             4.2.1.2.6.1   DISCUSSION OF   77

                             DEVIATIONS FROM DRAWINGS..

                4.2.1.2.7   IMPROPER WORK SEQUECNING...    78

                             4.2.1.2.7.1   DISCUSSION OF   78

                             IMPROPER WORK

                             SEQUENCING……………………

                4.2.1.2.8   ERRORS AND OMISSIONS IN        79

                DRAWINGS……………………………………..

                             4.2.1.2.8.1   DISCUSSION OF   80

                             ERRORS AND OMISSIONS IN

                             DRAWINGS…………………………

4.3   THE IMPACT OF REWORK ON PROJECT                      81

PERFORMANCE……………………………………………………..

        4.3.1 REWORK IMPACT ON PROJECT COST……………           81

               4.3.1.1   DISCUSSION OF REWORK IMPACT       85

               ON PROJECT COST……………………………..

        4.3.2 PERCENTAGE OF DELAY DUE TO REWORK……          86

               4.3.2.1   DISCUSSION OF PERCENTAGE OF       90

               DELAY DUE TO REWORK………………………


                 VIII
                   4.3.3   DISSATISFACTION OF CONTRACTORS AND         92

                   CLIENT………………………………………………………

                            4.3.3.1   DISCUSSION OF DISSATISFACTION   92

                            OF CONTRACTORS AND CLIENTS……………

CHAPTER FIVE…………………………………………………………………………..                            94

5   SUMMARY, CONCLUSION, AND RECOMMENDATIONS…………………...                94

       5.1   SUMMARY………………………………………………………………                          94

       5.2   CONCLUSION…………………………………………………………..                       97

       5.3   RECOMMENDATIONS………………………………………………..                      100

       5.4   RECOMMENDATIONS FOR FUTURE STUDIES………………….               103

    REFERENCES……………………………………………………………………….                            104

    APPENDIX…………………………………………………………………………...                            I




                              IX
                          LIST OF FIGURES



Figure 1.1   Labor Productivity for Construction and Manufacturing        2

             Industries during 1979 – 1998

Figure 2.1   Conceptual Model of Rework                                   9


Figure 2.2   Classification Model of Rework Causes                        21


Figure 2.3   A Proposed Rework Model                                      28


Figure 4.1   Average Frequency of Rework by Work Category                 41


Figure 4.2   Average Frequency of Insufficient Supervision on Different   53

             Work Categories

Figure 4.3   Average Frequency of Incompetent Supervision on Different    59

             Work Categories

Figure 4.4   Average Frequency of Poor Workmanship on Different Work      63

             Categories

Figure 4.5   Average Increase in Percent of cost as a Result of Rework    83


Figure 4.6   Average Percentage of Delay due to Rework                    88




                                    X
                               LIST OF TABLES



Table 1.1    Factors Negatively Affecting Labor Productivity and Their    3

             Rankings

Table 1.2    Factors Negatively Impacting Construction Productivity in    4

             Selected Countries

Table 4.1    Average Rework Frequency by Work Category                    40


Table 4.2    Rank Order of Work Categories According to their Rework      42

             Frequencies

Table 4.3    Average Frequency of Rework Causes / work Categories         51


Table 4.4    Average Frequency of Insufficient Supervision on Different   54

             Work Categories

Table 4.5    Average Frequency of Incompetent Supervision on Different    58

             Work Categories

Table 4.6    Average Frequency of Poor Workmanship on Different Work      64

             Categories

Table 4.7    Average Frequency of Improper Subcontractor Selection        68


Table 4.8    Average Frequency of Improper Work Protection                70


Table 4.9    Average Frequency of Lack of Coordination                    72


Table 4.10   Average Frequency of Wrong Material                          74



                                      XI
Table 4.11   Average Frequency of Defective Material                      75


Table 4.12   Average Frequency of Deviations from Drawings                77


Table 4.13   Average Frequency of Improper Work Sequencing                78


Table 4.14   Frequency of Errors and Omissions in Drawings                80


Table 4.15   Average Increase in Percent of Project cost as a Result of   82

             Rework

Table 4.16   Ranks of Increase in Percent of Project Cost as a Result of 84

             Rework

Table 4.17   Average Rework Frequency of Work Category and                86

             Corresponding Increase in Cost

Table 4.18   Average Percentage of Delay due to Rework                    87


Table 4.19   Ranks of Average Percentage of Delay due to Rework           89


Table 4.20   Average Frequency of Work Category and Corresponding         90

             Percentage of Delay due to Rework




                                       XII
                              1. INTRODUCTION



Productivity is a very important factor that influences the performance of all

organizations. Enhancement of productivity has many advantages including reducing

total cost and production duration, improved quality, increase of product market

share, increases of salaries and employment (Kazaz and Ulubeyli, 2007).


Generally, and as suggested by Tucker (2003) productivity growth is the most

important economic indicator and through it fast living standards growth could be

attained.


Labor productivity is defined as the output per working hour, and is one of the best

production efficiency indicators (Rojass and Aramvareekul, 2003).


During 1980s and 1990s most of the U.S. economy sectors showed growth in their

labor productivity, while the only sector which had noticeable decline in its labor

productivity was the construction sector. Figure 1.1 illustrates the relationship

between the labor productivity in the manufacturing sectors and the construction

sector.


Enshassi et al. (2007) indentified 45 factors that negatively affect construction labor

productivity, rework was ranked 11th among them. Table1.1 lists these factors as well

as their rankings.


In a comparative study of construction productivity problems in selected countries as

listed in Table 1.2, Kaming et al. (1997) as cited by Alwi, (2003), identified these

problems to include lack of material, lack of equipment, interference, absenteeism,

supervision delays, and rework. It is interesting to note rework was ranked as the

                                          1
second problem in productivity in Indonesia and Nigeria, and the third problem in the

United Kingdom and the United States of America.




Figure 1.1: Labor Productivity for Construction and Manufacturing Industries During
1979 - 1998
Source: Rojas and Aramvareekul, 2003



Rework is defined by Love and Edwards (2004a) as "the unnecessary effort of

redoing a process or an activity that was incorrectly implemented in the first time"

p.259.


As rework is a major contributor of poor productivity in construction, here comes the

interest in investigating rework, its causes and impact on project performance in

construction projects.



                                         2
Table 1.1: Factors Negatively Affecting Labor Productivity and Their Rankings

Factors                                                    Rank
Material shortage                                                  1
Lack of labour experience                                          2
Lack of labour surveillance                                        3
Misunderstanding between labour and superintendents                4
Drawings and specifications alterations during execution           5
Payment delay                                                      6
Labour disloyalty                                                  7
Inspection delay                                                   8
Working 7 days per week without taking holiday                     9
Tool and equipment shortage                                       10
Rework                                                            11
Misuse of time schedule                                           12
Accidents                                                         13
Labour dissatisfaction                                            14
Supervisors’ absenteeism                                          15
Insufficiency of equipment                                        16
Misunderstanding among labour                                     17
Low quality of raw material                                       18
Working within a confined space                                   19
Unsuitability of material storage location                        20
Lack of financial motivation system                               21
High quality of required work                                     22
Violation of safety precautions                                   23
Interference                                                      24
Lack of competition                                               25
Method of employment (using direct work system)                   26
Insufficient lighting                                             27
Increasing number of labours                                      28
Weather changes                                                   29
Increase of labour age                                            30
Working overtime                                                  31
Lack of labour recognition programs                               32
Construction method                                               33
Type of activities in the project                                 34
Bad ventilation                                                   35
Augmentation of government regulations                            36
Working at high places                                            37
Lack of periodic meeting with labour                              38
Non-provision of transport means                                  39
Lack of place for eating and relaxation                           40
Labour absenteeism                                                41
Labour personal problems                                          42
Not employing of safety officer on the construction site          43
Lack of training sessions                                         44
Noise                                                             45



Source: Enshassi et al. 2007




                                            3
Table 1.2 Factors Negatively Impacting Construction Productivity in Selected

Countries

                              Indonesia          Nigeria          UK           USA
   Productivity factors
                                 Rank             Rank           Rank          Rank

Lack of material                   1               1               1             1

Lack of equipment                  5               3               5             2

Interference                       3               6               2             5

Absenteeism                        4               5               6             6

Supervision delays                 6               4               4             4

Rework                             2               2               3             3



Source: Kaming et al., 1997 as cited by Alwi, 2003



This study is an effort to investigate rework severity in terms of its frequency in

different work categories, its direct and indirect causes, its impact on project cost and

time, and finally its impact on clients' and contractors' satisfaction.



1.1 Research Objectives

The overall objective of this research is the improvement of construction productivity

in the Kingdom through the use of a case study and by focusing on rework as one of

the major determinants of construction productivity. The specific objectives of the

study are to:

   1. Determine the severity of rework and its frequencies in the different work

       categories in a case study of a construction project at Al-Khobar city- Eastern

       Province of Saudi Arabia.

   2. Identify the direct and indirect causes of rework and their frequencies of

       occurrence in the case study.

                                             4
   3. Identify the impact of rework on project cost and time as well as on client’s

       and contractors’ satisfaction.

   4. Make recommendations on minimizing rework in projects similar to the case

       study.



1.2 Statement of the Problem

There are many causes which may lead to rework in construction projects, some

causes are direct and result in work activities to be done more than one time. And

other causes are indirect and may lead to rework indirectly. Regardless of these

causes, the resulting rework will have the potential to negatively affect the project

time and cost as well as the satisfaction of both contractor and client.


The statement of the problem in this research is simply the guiding questions to

achieve the above research objectives and hence can be stated as follows:


     1. What is the severity of rework and its frequencies in different work categories

         in the case study project?

     2. What are the direct and indirect rework causes in the case study?

     3. What is the impact of rework on project cost and time as well as on clients'

         and contractors' satisfaction?

     4. How to minimize rework in projects similar to the case study?



1.3 Significance of the Study

This study is significant in several aspects including:

   1. It addresses rework as a major determinant of construction productivity.




                                            5
   2. It will contribute to the understanding of rework in construction projects

       similar to the case study in the Eastern Province in Saudi Arabia.

   3. It increases awareness of the possible problems which may result from rework.

   4. The above three aspects of the study have the potential of leading to the

       following benefits:

            Enhancing productivity levels by reducing rework, which in turn will

               positively impact the progress of the project and consequently the

               project performance.

            Reducing cost overruns associated with rework.

            Reducing time overruns associated with rework.

            Raising the morale of employees of different project participants which

               result from doing perfect work fist time.

            Reducing or minimizing any possible conflicts which may result

               because of rework.

            Considering any possible rework from direct or indirect causes in the

               preplanning phase of the project.

   5. This study of rework is among the first research on rework in Saudi Arabia.



1.4 Scope and Limitations

The study is limited to a case study of a residential commercial tower at Al-khobar –

Eastern Province – KSA. Consequently, this leads to the following limitations:

    1. The construction work categories covered in the study are those involving

       construction contractors who are still working in the project during the data

       collection phase.

    2. Information and data are based on the opinions of the interviewed participants,

       not on well documented records. This and the above limitation were due to

       the limited time and scope requirements for CEM engineering reports.


                                          6
It is however important to recognize the following implications of the above

limitations:

   1. As in any case study, external validity, i.e. generalization to other types of

       construction or even similar construction should be viewed with extreme

       caution since the presence of different factors may lead to different findings

       and conclusions. The same can be said about the internal generalization to the

       entire project in the case study.

   2. The reliability and validity of the collected data are constrained by the above

       method of data collection.




                                           7
                          2. LITERATURE REVIEW



This literature review starts with defining construction rework, followed by

identifying and describing some of the rework models. The literature review

concludes by reporting the findings on how to reduce rework.



2.1 Rework Definition


Rework is defined as the non-required effort of re-doing a process or activity that was

faulty executed at the first time (Love and Edwards, 2004a). Also rework means that

work must be redone because it was not following requirements (Hwang et al., 2009).



2.2 Rework Models


Three rework models are presented in this section. The first model is a conceptual

model of the causes of rework and its impact on project productivity and project

performance. The second model is a classification of causes of rework. And the third

model of rework is a proposed rework model proposed by the writer of this report.



2.2.1 A Conceptual Model of Rework


The conceptual model of rework is presented in Figure 2.1, It portrays project

characteristics, organizational management practices and project management

practices as the factors impacting directly or indirectly rework and subsequently

influencing productivity and project performance (Love and Edwards, 2004a).


The details of this conceptual model are presented in the following sections.


                                           8
Figure 2.1: Conceptual Model of Rework
Source: Love and Edwards (2004a).




2.2.1.1 Project Characteristics


Love and Edwards (2004a) identified project characteristics that may have an impact

on project performance. These characteristics include procurement method, tendering

method, project type, facility type, contract value, contract duration, cost growth,

schedule growth, negotiated contracts, gross floor area, and number of stories.

However, after the authors conducted a study on " Determinants of Rework in

                                         9
Building construction Projects", they found that only procurement method as a project

characteristic could cause rework.


Clough et al. (2005) identified two main groups of construction contracts. The first

group includes those types of contracts that the owner chooses the contractor based on

competitive bidding, and in the second group the owner negotiates the contract

directly with the contractor to choose the contractor.


Competitive bid contracts contains two types and its basis is a fixed price. The first

type is a lump-sum contract its cost amount is fixed sum and it covers all works

included in the contract documents. The second type is a unit price contract and it is

based on proposed quantities of specified work items with a unit price for each work

item.


In the negotiated contracts, the contract is based on any agreeable basis between the

owner and the contractor, lump-sum, unit price or cost plus fee. Negotiated contracts

mainly use cost plus fee contracts.


In the fixed lump sum contract method, contract documents are considered to be

complete before construction works starts, that's why theoretically less rework could

occur in such method (Love and Edwards, 2004a).



2.2.1.2 Organizational Management Practices


Love and Edwards (2004a) identified organizational management practices that may

have impact on rework and project performance. These practices comprise

organizational learning practices, quality management practices, size of firm,

turnover, governance, and audit and control.


                                           10
Organizational learning is a wide term that can explain different types of learning in

an organization, such as programs to train individuals, group decision making related

to data, dialogue and reflection, a meaningful effort to raise learning to ameliorate

organizational performance (Cors, 2003).


One example of the organizational learning practices is that errors and defects could

be noticed and then identified only after their occurrences, and then they should be

used as learned lessons for improving future projects (Josephson et al. 2002),

otherwise, if errors and defects could be repeated in future projects.


Bossink (2002) suggested that quality management practices may be divided into six

categories, design practices, planning practices, system practices, goal practices,

positioning practices, and interaction practices. Each of these practices has a

framework containing key philosophies.


For the design practices, the key philosophies are design of quality strategy, quality of

inspection routines, and feedback of failure information to manufacturing processes.


For the planning practices the key philosophies are stage-by-stage implementation of

a quality strategy, and integral use of statistical analysis in manufacturing processes.


For the system practices, the key philosophies are systematic coordination,

monitoring, and documentation of quality procedures, and mutual harmonization and

coordination of design and manufacturing processes. The key philosophies of the goal

practices are quality goal setting and goal realization and continuous improvements of

procedures, services, and processes. The key philosophies of positioning practices are

remaining competitive in the marketplace through identification of unique


                                           11
opportunities related to quality, and making qualitative decisions to gain competitive

advantages. The key philosophies of the interaction practices are creation of value by

simultaneously aiming at customer satisfaction and employees’ satisfaction, and

creating synergy between the organization and the environment.


Failure to implement any of the above mentioned measure in any of the six categories

practices may lead to rework.


Size of the firm may contribute to rework. As the firm size gets much larger, there is a

tendering of lack of communication, coordination, and employees alienation which all

could lead to rework.


Turnover, as an element of organizational management practices, has an influence on

rework. It has been suggested that turnover of the work force could lead to more

rework because it will take some time for the new employees to adapt to their new

positions.


Governance of the firm is defined as "the group of principles that controls the division

of rights and responsibilities between the management, the board, the shareholders,

and other stakeholders" (Petrovic-Lazarevic S. 2004 as reported by Petrovic-

Lazarevic S. 2003 p.2.). Thus, compromising those rights and responsibilities will

negatively impact quality and hence increase the potential for rework.


Related to audit and control, important changes in design must be reviewed and

authorized through a systematic and well organized scope and change control

program that has been well studied by the client's representative side by side with the

project team. Lack of auditing means more possibilities of client changes in design,

which results in more rework (Love and Edwards 2004b).

                                          12
2.2.1.3 Project Management Practices


Love and Edwards (2004a) identified project management practices that may

contribute to rework occurrences and may have impact on project performance and

productivity. These practices include those related to client, design team, site

management, subcontractors, project scope, contract documentation, communication,

project strategies, and design management.


Palaneswaran (2006) stated that clients could cause rework occurrences to happen

when they make changes to works after some work has been commenced. Other

factors related to clients that contribute to rework include lack of knowledge and

experience regarding design and construction processes, inadequate funds targeted to

site investigation, and insufficient clients' involvement in the project.


Love and Edwards (2004b) suggested that design team could be a contributor to

rework occurrences, if there were no coordination and integration among the team

members throughout the contract documents production process.


Site management is a factor that could cause rework as proposed by Palaneeswaran et

al. (2005), that poor planning and coordination of resources and wrong usage of

quality management practices were the most frequent causes among site management

related factors that were causing rework.


Among subcontractor-related factors which cause rework are damages, defects, poor

workmanship, insufficient managerial or skills of supervision, and using poor quality

material (Palaneswaran, 2006).


Concerning the project scope, when it is not properly defined or if the requirements of

the occupier or the client are incomplete or limited by the time of finalizing contract

                                            13
documents, then changes by clients or occupiers will be a necessity during

construction and consequently will cause rework (Love and Edwards, 2004a).


Contract documentation is a factor which causes rework. For instance, the lack of

experience of the design team or when little time is allocated to contract documents

will cause errors in the contract documents which will eventually result in rework.

Additionally, poor coordination within the design process could contribute to the

occurrences of service clashing which could cause rework (Love and Edwards

2004b).


Communication is a very big contributor to rework in construction as described by

Love and Sohal (2003). Poor communication between clients and design consultants

leads to rework because most of clients build only once in their lives and as a result

they would not be familiar with what they should do throughout the design and

construction processes.


Procurement strategies include contractual incentives, project quality management

systems, pre-qualification, and rational contracting. As proposed by Bubshait (2003),

the use of incentives and disincentives in contract provisions ascertains that

contractors do the best they can to handle factors contributing to labor productivity,

cost and time overrun in projects, thus reducing the possibilities of rework

occurrences.


Design management may contribute to rework. Love et al. (2004) identified strategies

for design management including value management, design for construction,

computer visualization, subcontractor/supplier involvement in design, constructability

analysis, design scope freezing, and team building. Value management is a technique

used for reevaluation of the functionality and client’s requirements to reduce the

                                         14
client’s changes during construction which may result in rework. Also the ineffective

use of IT by design team members contributes to rework. The lack of interaction

which is an example of the ineffective use of information technology can result in

non-timely information transfer among design team members can impose significant

restrictions on decision making.



2.2.1.4 Productivity


The conceptual model presented in Figure 2.1, shows the effect of rework on

productivity through its impact on the morale level, dilution of supervision, conflict,

absenteeism, fatigue, and communication. Rework not only affects cost and schedule

growth but also has a negative influence on intra and inter-organizational relations

and the psychological well being of individuals (Love and Edwards, 2004a).


At the individual level, stress, fatigue, absenteeism, de-motivation, and poor morale

were identified as indirect results of rework. At the organizational level, reduced

profit, diminished professional image, intra-organizational conflict, and loss of future

work were identified as the indirect results of rework. At the project level,

dissatisfaction of clients or end-users was indirectly linked to rework (Love, 2002b).


One of the productivity elements that could be affected by rework is the dilution of

supervision. It has been suggested that rework leads to diversion of resources which in

turn dilutes supervision in other parts of a project. Three effects of such dilution could

happen. Firstly, extra supervision will be needed and rework resulted may need some

extra time from subcontractors to do the rework, which may cause stacking in

subcontractors' trades. Secondly, rework could occur where supervision is limited and




                                           15
cannot cover all project areas. And lastly, safety could be compromised (Love and

Edwards, 2004a).


Conflict may result from rework. The main four types of organizational conflicts are

interpersonal   conflict,   intergroup    conflict,     intra-group   conflict,   and   inter-

organizational conflict, Love (2002) suggested that inter-organizational conflict is an

indirect consequence of rework; in case that rework happened then conflict may arise

between the client and the contractor about the causes of rework.


These negative outcomes of rework have their ripple effect on absenteeism, fatigue,

and communication, which in turn impact productivity.



2.2.1.5 Project Performance


The conceptual model of Figure 2.1shows that rework impacts project performance in

terms of cost, time, contractual claims and disputes, client satisfaction, design team

satisfaction, contractor's satisfaction, and quality.


Concerning project costs and as suggested by Hwang (2009), changes by owner and

errors and omissions in design were the most frequent causes of costs overrun. More

specifically, rework is a direct contributor to cost and schedule overruns.


It was suggested by “New South Wales Government” (2008) that typical motives for

claims and disputes comprise financial imperatives, interpretation of contract

documentation, unanticipated events/circumstances, unrealized expectations, and

variations requested by the client. Financial imperatives happen if the contractor is not

getting the financial return on his contract, or if the client is subjected to budget

overrun. Interpretation of contract documentation may occur when the description of


                                             16
the contract clauses is not accurate or precise which may be interpreted by the

contractor and client differently, thus claim then dispute may be the result.

Unanticipated events/circumstances such as unexpected site conditions may arise and

may cause claims then disputes. Unrealized expectations means that the contract will

place explicit or implicit performance commitments like time and quality on both

parties for them to be clear how those performance commitments will be met.

Variations requested by the client may cause claims and then disputes. All of the

above typical motives to claims may be caused by rework.


Karna (2009) suggested that clients’ satisfaction means that the client is satisfied with

the quality of the product or services and they meet or exceeds his expectations, the

client is not satisfied when the quality of a product or a service is under his

expectations. In construction, client satisfaction could be measured by the limit to

which the physical facility and the construction process meets or exceeds his

expectations. Five important factors influence the satisfaction of the client and they

are:


          The contractual quality of the work.

          The implementation of the quality assurance procedures that all parties have

           agreed upon.

          The level of functionality of the contractor’s handover control.

          The quality of building’ handover and maintenance material manual.

          The temporal management of the construction process, i.e. the defects and

           deficiencies which had been commented in the handing over process were

           rectified.




                                              17
The inability for the contractor to satisfy any of the above measures may lead to

rework which consequently lead to client’s dissatisfaction.


Regarding the contractor’s satisfaction, Rober and Mclin (2005) proposed key

indicators that measure the overall health of the contractor firm or in other words its

satisfaction. These include liquidity indicator, schedule variance indicator, work in

progress reporting, and scorecard indicator.


About the liquidity indicator, as cash is crucial in keeping contracting business life.

Most of the sins could be forgivable but the unforgivable one is running out of cash.

Client’s payment lateness, delays in schedules, invoice processing, vendor /

subcontractor payments, labor costs, and many other factors affect the timing of cash

receipt. To understand cash flow for the project manager is of crucial importance. It

should be known to the manager if the project is providing liquidity or not because if

the liquidity for the project is known, the manager can work towards improving it.


Schedule variance indicator is an important indicator to contractors. General

contractors who are able to handover projects on schedule have a competitive

advantage and vice versa. A good schedule saves money and time for all participants

of the project.


Related to work-in-progress reporting, for corrective actions to be in time, progress

reports facilitates this process, also to ensure that project is progressing according to

the scheduled plans. That’s why work-in-progress reporting is a crucial indicator for

contractors to know the status progress of the project.




                                           18
Scorecard indicator is to measure the qualitative performance of the organization.

Organizations that use scorecard indicators have good safety records, high

productivity, good quality, employee retention, and client satisfaction.


Above indicators could measure the satisfaction or dissatisfaction of the contractor. If

rework happens it will affect the satisfaction of the contractor because either of the

cost or time overruns (Rober and Mclin, 2005).


Quality is very crucial in construction projects, Chan and Tam (2000) suggested that

any product should have some specific standard in any industry that provides

customer satisfaction and value for money. They also identified the main factors that

influence quality performance in construction projects to include client, project,

project environment, project team leaders, and project management procedures.


Client- related issues which may affect quality such as the client’s nature i.e. whether

he is from private or public sector, clarity of project mission, and their ability of

making decisions.


The project characteristics may influence the project quality, some of the project

characteristics include type of the project, number of stories, nature of the project

whether it is new project or refurbishment project that costs higher than new projects.


The external project environments influencing the construction process include

physical, economic, socio-political, and industrial relations. These aspects can make

uncertainty not only related to prices but also related to the demand of the building.

Project team leaders are the group of professionals from different parties that combine

for completing the design and construction stages. Their performance could be

evaluated through their skills and experiences.



                                           19
Quality performance has been considered as the function of the project procedures.

Project management actions, i.e. organizational decision making include choosing the

overall strategy, setting specific objectives, designing structures and processes,

selecting people, delegating responsibilities, evaluating results and initiating changes.


When rework happens it will affect quality through the negative effect on any of its

subcomponents (Chan and Tam, 2000).



2.2.2 Classification Model of Rework Causes


The classification model of rework causes as prescribed in Figure 2.2, divides rework

causes into five main categories, leadership and communication, human resource

capabilities, engineering and review, construction planning and scheduling, and

material and equipment supply. Under each category there are four main causes which

contribute to rework. The following subsections provide a description of these causes

(Rework Committee, 2001).



2.2.2.1 Leadership and Communications


Under leadership and communications, four factors that lead to rework including,

poor communication between field inspector and constructor, lack of safety and

quality assurance/quality control commitment, ineffective management of project

team, and lack of end user's contribution in design and construction processes.


Poor communication between field inspector and constructor may lead to rework.

Winkler (2009) advises the site inspector to establish a good working relationship

with the contractor.



                                           20
Figure 2.2: Classification Model of Rework Causes
Source: Rework Committee, (2001).


For a better functional working relationship between the two parties trust is a must,

the inspector's homework must be done before any required rework from the

contractor. Studying the work category items and the required specifications, as well

as the contract drawings are a must before the field inspector request any rework to be

done.

All needed safety measures should be implemented in site. Michigan Occupational

Safety and Health Administration, (2005), proposes that the contractor should protect

workers safety and health by adopting several measures including using a qualified

safety person, making regular job site safety inspections, enforcing the use of safety

equipment, following safety procedures and rules, providing on-going safety training,


                                          21
and enforcing safety rules and using appropriate discipline. Lack of safety, i.e. not

forcing any of the above measures may lead to rework.


Louisiana Department of Transportation and Development (2008) defines the quality

control as "the best usage of operational techniques and activities to maintain the

quality of the inputs and outputs to specifications and to commit to quality and

requirements" p. 3. Whereas it defines the quality assurance as "the management and

senior technical levels are employing the needed actions methods and procedures to

get the required quality of the desired product" p. 3.


Parsons (2007) defines quality control as "the implementation of all needed

inspections, tests, and production controls to fulfill the required standards of quality

and to rectify any deficiencies from non-conformance to quality" p.1-4. And that the

construction manager provides the quality assurance through monitoring and

inspecting the effectiveness of the contractor’s quality control program and is sure

that all contract requirements are achieved by the contractor. Any deviations from the

quality control and the quality assurance may lead to rework.


Ineffective management of the project team is a factor that may affect rework. Alwi et

al. (1999) suggest that poor skills of supervisors and lack in their training contributed

to construction costs increase, because of their incompetency in planning, and

communicating with workers, and guiding work activities which all may cause

rework.


Lack of end user's contribution in design and construction processes may contribute to

rework. Love and Smith (2003) contended that lack of communications between

clients and design consultants was a big contributor to rework. Because most of

clients build only once in their lives and their role in the design and construction

                                           22
processes is unclear. That's why clients should be well informed about their role in the

building procurement as well as their involvement in the design and construction

processes, otherwise many changes may lead to rework because the clients do not

know their exact role in the process.



2.2.2.2 Human Resource Capabilities


The factors causing rework under human resource capabilities category are excessive

overtime, insufficient skill levels, unclear work specifications, and incompetent

supervision and job planning.


Excessive overtime is typically utilized when the project is behind schedule. Toole

(2005) proposes that such excessive overtime will cause fatigue to workers and

consequently reduces productivity and result in poor quality of work which will lead

to rework.


An insufficient skill level is a factor which may lead to rework. Alwi et al. (1999)

suggest that supervisors and labor skills are among the fundamental prerequisites for

implementing any construction project, and they are inversely related to rework costs.

Palaneeswaran et al. (2005) also identify the lack of managerial and supervisory skills

as a main factor that causes rework.


Unclear work specification may lead to rework. Clough et al.(2005) suggest that

specifications are the written guidelines which contains statements concerning all

project requirements such as materials, workmanship, and operating characteristics.

Love and Sohal (2003) state that contractors most of the time are considered the

managers of the production process; therefore they need the right information to better



                                          23
manage their subcontractors. Rework may incur if the information is incomplete,

inappropriate or conflicting.


Incompetent supervision and job planning also are elements that could lead to rework,

among site management related factors, poor planning and lack of coordination of

resources have been identified as big contributors to rework, (Palaneeswaran et al.,

2005). Makulsawatudom and Sinthawanarong (2004) propose that incompetent

supervisors   solely   are      held   responsible   of   incorrectness   of   works   and

inappropriateness of usage of tools and equipments, incompetent supervisors are

contributors to lack of productivity in construction.



2.2.2.3 Engineering and Review


The factors causing rework under engineering and review are design not sufficiently

advanced, scope and design changes, poor document control, and errors and

omissions.

When design is not sufficiently advanced it may cause rework. Josephson et al. (2002)

suggested that there are some factors that may cause rework referring to design causes

like incomplete designs. Love et al. (2004) suggested that when time boxing

(limited duration) is allocated to design tasks, the result could be insufficiently

advanced contract documents which will lead to rework.


Scope and design changes also may cause rework. Love et al. (2004) explained that

when design scope freezing is implemented the likelihood of rework to happen will

reduce, and the reverse is also true. Design changes may cause rework whether those

changes were initiated by clients, contractor, or design team members.




                                             24
Poor document control, and errors and omissions in contract drawings may lead to

rework. Love et al. (2004) suggested that poor technical knowledge and lack of

experience can result in errors and omissions in contract drawings which may lead to

rework. Love et al. (2000) clarified that many factors may lead to errors and

omissions in contract drawings, such as low design fees, and schedule pressures

which consequently may cause rework.



2.2.2.4 Construction Planning and Scheduling


The factors causing rework under construction planning and scheduling are unrealistic

schedule, late owner input, untimely deliveries, and insufficient commissioning and

start up resourcing.


Unrealistic schedule or in other words schedule pressures may lead to rework. Nepal

et al.(2006) suggested that schedule pressures can lead to working out of sequence,

resulted in work defects, cutting corners, and reduction of the motivation to work

which all may lead to rework.


Late owner input may result in design changes and increased likelihood of errors and

omissions which all could lead to rework (Hwang 2009).


Untimely deliveries as a factor influencing rework concerning construction planning

and scheduling was not discussed through the literature of rework studies.


Commissioning was defined by Portland Energy Conservation, (2000) as "a

systematic process of ascertaining the performance of all building systems

interactively as per the contract documents, the client requirements, and operational

requirements" P.2. While resourcing is the process of employees and materials


                                          25
allocation to fulfill the operation process of the facility. If insufficient commissioning

was done and resourcing started, this may lead to nonconformance to any of the

contract documents, client’s requirements, or operational requirements which may

lead to rework.



2.2.2.5 Materials and Equipment Supply


The factors causing rework under materials and equipment supply are noncompliance

with specifications, untimely deliveries, prefabrication not to project specifications,

and materials not in the right place when needed.


Noncompliance with specifications is a factor that may cause rework; Josephson et al.

(2002) suggested that faulty manufacturing of material was a main contributor to

rework.


Untimely deliveries, either too late or too early, is a factor that contributes to rework.

Among the material-related causes of rework, lack of material delivery was ranked

the first (Josephson et al., 2002).


Prefabrication not to project specifications as a factor could cause rework; but

Josephson et al. (2002) noted that prefabricated components with wrong dimensions

and quantities were unusual and thus were not contributing to rework.


Materials were not in the right place when needed is a factor that may cause rework.

Faults in material administration were identified by Josephson et al. (2002) as one

major causes of rework.




                                           26
2.2.3 A Proposed Rework Model


Based on the above literature review of the factors causing rework in the construction,

and the experience of the writer of this report in the case study project, the writer is

proposing a rework model for the causes of rework.


The proposed rework model is shown in Figure 2.3 and is composed of two main

categories of factors cause rework. Direct rework causes, and indirect rework causes.



2.2.3.1 Direct Rework Causes


The direct rework causes comprise causes that will directly lead to rework including

poor workmanship, insufficient supervision, incompetent supervision, wrong material,

defective material, deviations from drawings, and errors and omissions in drawings.


Poor workmanship is the output characteristic of untrained or inexperienced workers

which results in defective works. When using such poor workmanship, rework will be

the outcome.


Regarding insufficient supervision as a direct rework cause, a construction supervisor

is expected to meet many responsibilities including (www.SkilledWorker.com):


     Supervise, co-ordinate and schedule the tasks and activities of all construction

        workers in all different construction activities.

     Create methods to fulfill work schedule requirements.

     Demand materials and supplies.

     Solve work problems and propose measures to enhance productivity.

     Arrange training for workers.

     Assess workers performance and recommend workers hiring and promotions.

                                            27
                                                         Direct Rework Causes
Indirect Rework Causes
                                                         . Insufficient supervision
. Improper subcontractor
selection                                                . Incompetent supervision


. Improper work protection      → Rework ←. Poor workmanship
. Lack of coordination                                   . Wrong material
. Improper work sequencing                               . Defective material
                                                         . Deviations from drawings
                                                         . Errors and omissions in
                                                         drawings



Figure 2.3: A Proposed Rework Model


     Prepare reports of production and other reports.


Insufficient supervision refers to the amount of supervision provided to the workers

When supervision is below the required amount workers may not give adequate care

to the work they are doing, and that may lead to bad quality which causes rework.


Incompetent supervision refers to the quality of supervision where the supervisor does

not have enough supervision experience and skills. In such cases the supervisor could

misunderstand the engineer’s instructions, and consequently the supervisor will

mislead the foremen or workers under his supervision thus causing rework.


Using wrong materials or defective materials will lead to rejecting the constructed

works; therefore, rework will be the result.


Deviation from drawings refers to the non-compliance of project drawings, whether

contract plans or approved shop drawings. By inspecting works and finding that work

was not executed as per drawings, work should be rectified and redone.




                                           28
When errors or omissions found in drawings either those drawings are contract

documents or shop drawings, such drawings should be rectified which means that

rework will be the result.



2.2.3.2 Indirect Rework Causes


Indirect rework causes refer to a set of causes that they do not in themselves cause

rework but they create the situations that will cause rework. These indirect rework

causes consist of improper subcontractor selection, improper work protection, lack of

coordination, and improper work sequencing.


If an improper subcontractor is selected, the work he executes may include defects

which may cause the works to be re-executed another time. Arslan et al. (2008)

suggested that the appropriate selection of the subcontractors is very crucial for the

overall performance of the project. For the general contractor to select the most

appropriate subcontractor he should consider the subcontractor's financial and

technical capabilities. Other factors to consider include production quality,

qualifications of staff, company’s reputation, and ability to complete work on time.


Improper work protection, if executed works are not protected properly they will be

exposed to damages from other work, which will lead to rework.


Lack of coordination among work categories may lead to rework. Especially,

coordination among air conditioning ducts, electrical conduits, and plumbing pipes. If

any of them was executed without the proper coordination with other categories, in

most cases rework will be the result.




                                          29
Improper execution timing refers to sequencing the work. For instance executing

flooring tiles works before starting painting works, such action will lead to certain

damages in flooring tiles works, which result in rework.



2.3 Rework Minimization


To reduce or to minimize rework occurrences in construction projects many issues

should be considered such as changes, value management, use of information

technology, design scope freezing, supervisors training, quality control plan, and

project inspection


Change is defined by An Oracle White Paper, (2009) as the difference between the

contract requirements as it was set in the original contract between parties, and the

extra requirements during the actual construction of the project. Changes can be

classified into directed or constructive changes. Directed changes are the changes that

are directed by the owner coupled with his belief that those changes are different from

the contract original requirements. Examples of those directed changes are addition or

deletion of work, revision to material specifications, revision to project phasing,

change to site access or hours of operation, and change to contract duration.

Constructive changes are not recognized by the owner as changes from the original

contract requirements, such as the difficulty of executing works as designed, the

project usage by the owner before completion, and untimely inspections.


Any changes whether were initiated by the owner or the contractor may lead to

rework, so as changes get to minimum or reduced, consequently the rework

occurrences will be reduced or minimized.




                                          30
Value was identified by Department of Housing and Works (2005), as the benefit

given by the project to the client. Value means that the maximum benefits are assured

to the client within time, cost, and quality limits.


Value management is a systematic, structured and analytical methodology that

pursued to attain the necessary project functions at the minimum total cost, maintain

the required levels of quality and performance. The consistent meaning behind value

management is that there are always many paths to attain any function, and there are

many solutions and alternatives to get the most valuable solution.


The objectives of the value management are innovative and economic by doing the

following: unnecessary expenders identification, challenging assumptions, generating

various options and ideas, promoting innovations, enhancing resources, saving time,

money, and energy, simplifying methods and procedures, eliminating redundant

features, updating standards, criteria, and procedures, ameliorating team performance

and other synergies, and considering the whole life of cycle costs (Department of

Housing and Works, 2005).


When applying value management principles that will lead to enhancing project

performance, maintaining the quality and reducing costs. Consequently, that will lead

to minimization of rework.


The use of information technology in the construction industry is very crucial to the

enhancement of project performance, Rivard (2000) observes that many business

processes are being computerized and there is a trend in computerizing the remaining

processes. CAD software is used by most of the architectural and engineering firms.

The business processes that are already computerized are bookkeeping, invoicing, and

specifications writing. Many firms have presence on the Web, and they are

                                             31
exchanging information digitally. IT has raised productivity in all business processes,

especially in general administration, design and project management. IT increased the

quality of documents, the speed of work, enhanced the financial control, and provided

better communications, simpler and faster access to common data, and decreased the

number of mistakes in documentation. Using the IT in management, planning,

monitoring, and communication processes will decrease the probability of rework to

incur.


Design scope freezing has been identified by Love and Edwards (2004a) as a good

technique to reduce changes which consequently will reduce the probability of rework

occurrences.


The Business Roundtable, (1990) proposed that supervisors' formal training can

ameliorate their skills and consequently enhance construction projects productivity.

Formal training programs could be obtained from contractors’ associations, trade

schools, consultants and universities. Training is cost effective if it is oriented to

fulfill a certain need. Specific need can be identified by analysis then specifying the

training to satisfy that need. Formal analysis must study what kind of training and

amount of training needed and by whom. When training is done in a continuous basis

it will be more effective than if done intermittently. If it is considered to be an integral

part of the project management it will be more effective.


Concerning the quality control plan to be implemented, U.S. Department of

Transportation, (1998) identifies several requirements of the quality control plan

including process control testing, inspection control procedure, description of records,

personnel qualifications, and subcontractors' qualification. Process control testing,

involves listing the materials to be tested, specifying the location of the sampling, and


                                            32
frequency of testing. Inspection control procedures cover several requirements to be

met addressed in each construction phase. These requirements include reviewing all

contracts, ascertaining the compliance of materials to contract documents,

coordinating all submittals, ascertaining capability of equipments and personnel with

contract requirements, ascertaining the accomplishment of the preliminary testing,

and coordinate surveying of the work. The description of records involve maintaining

in the site, the inspector’s daily logs, project log book ”field diaries”, photographs

labeled and dated for record purposes, construction progress payments, files “filing

and disposition”, safety and accident reports, punch (deficiency) list, contractor

technical submittals, contract modifications, contractor required notices “posting and

maintenance”, special reports, completion report, and final acceptance report.

Personnel qualifications are maintaining documents concerning name, authority,

relevant experience, and qualifications of the person who is responsible for the

inspection system as well as the person who is responsible for the testing system.

Regarding subcontractors' pre-qualifications, they must include the work of the

subcontractor and the way of communication between the subcontractor and the

contractor or other subcontractor’s organization. If the quality control plan is well

implemented the probability of rework will be appreciably reduced.


Project inspection was defined by Division of Engineering, (2004) as a process that

ascertains that the works of the contractor is complied with the requirements of the

contract. Inspection considered being a very important element of the construction

and contract administration. The frequency and method of the construction

inspections depends mainly on the project complexity and the construction codes. The

objectives of the inspections which should be done by the construction inspector and

by the field inspector who is the consultant or the owner representative are to:

                                         33
ascertain the compliance of all construction activities with the contract requirements

and that all performed work is complied with best construction practices, verify that

the materials and the equipments used in the project meet contract requirements,

monitor contract labor requirements, provide sufficient and precise reports, ascertain

that construction safety measures are implemented, verify that approved contractor

submittals are available before commencement of work, and verify that project

progress agrees with approved project schedules. Enforcing the above inspection

required will ensure the quality of works and will reduce the occurrences of rework.




                                          34
                        3 RESEARCH RETHODOLOGY



This chapter is divided into two sections; the first section will describe the case study,

and the second section will explain how the data were collected.



3.1 Case Study

The case study is a residential commercial tower at Al- khobar city – Eastern Province,

the tower consists of fifteen floors, divided into seven residential floors, one swimming

pool, gymnasium and games area floor, two showroom floors, one restaurant floor on top

of the building, two service floors, and two basement floors for car parking.


The procurement method which was used in the project consisted of separate contracts

for almost each work category. A separate contract was awarded for each of the

following categories: the masonry and concrete works, the finishing and electrical works,

the air conditioning works, the elevators' works, the aluminum and glass works, the

wooden works, the plumbing works, the fire fighting and fire protection works. Many

types of contracts were used between the project's owner and contractors in the case

study project, the types of the contracts include fixed lump-sum contracts, unit price

contracts, and cost plus fee contracts. The owner representative was working as a

construction manager, with the primary responsibility of coordinating between the

different contactors of the different work categories.


The role of the designer was limited to producing a part of the contract documents. Only

architectural, structural, electrical drawings were produced by the designer. Other


                                             35
drawings such as air conditioning, plumbing, wooden, aluminum and glass, and elevators

drawings were left for each specialty contractor to produce.


This project has been chosen as a case study because of the appropriate amount of rework

that had been noticed by the writer of this report who was working as an architectural

consultant.


At the time of collecting the data, the project was in the hand-over stage, and the

organizations were still present in the project included the owner representative engineer,

a group of engineers representing the consultant organization, and contractors of different

work categories including finishing and electrical, aluminum and glass, fire fighting and

fire protection, plumbing, elevators, and air conditioning.


Those of these contractors (finishing, electrical, aluminum and glass and plumbing)

employ subcontractors.



3.2 Data Collection


Data collection was done through a personal interview since it allows more probing into

the issued questioned.


An interview schedule was prepared in a form of simple questions to cover five main

issues and they were as follows:


   1. For the following work categories, how frequent were rework occurrences?

   2. For each work category, indicate the cause of rework and its frequency.

   3. What percentage increase in cost for each work category as a result of rework?


                                            36
   4. What percentage delay due to rework?

   5. Indicate any impact of rework on project performance or productivity other than

       cost and time.


And the interviewees were asked more questions in the interview to explain more about

how the rework causes caused rework in each work category, and the circumstances of

the execution of each work category.


The interview schedule (Appendix A) lists choices of rework causes, based on the

proposed rework model presented in Fig. 2.3, to help the interviewees to respond to the

possible causes of rework. The respondents were asked to indicate the frequency of

rework and the frequency of possible causes using a frequency scale of 0,1,2,3,4

representing never, rarely, sometime, often, and always respectively.


The degree of frequency depends on the number of repetitions of rework cause or of

rework in general, if rework cause or rework is repeated many times, then its frequency

will get much higher and vice versa.


The degree of severity of rework cause or of rework may depend on the degree of their

frequencies or may be judged from the amount of cost and time caused due to such

rework cause or due to rework.


The interviewees were the key participants in the case study project, representing the

owner, consultant, and contractors, in total they were ten interviewees, one owner

representative (playing the role of the construction coordinator between the contractors),

three representatives of the consultant (playing the role of the construction supervisors)



                                            37
and six contractor supervisors and they were the heads of the six contractors that were

executing the remaining work in the case study project.


The consultant's and the contractors' representatives will be designated in the rest of the

report as follows: consultant A is the Architect's consultant, consultant B is the electrical

consultant, consultant C is the mechanical consultant, contractor A is the supervisor of

finishing and electrical contractor, contractor B is the supervisor of the aluminum and

glass contractor, contractor C is the supervisor of the plumbing contractor, contractor D is

the supervisor of the fire protection and fire fighting contractor, contractor E is the

supervisor of the wood works contractor, and contractor F is the supervisor of the

elevators contractor.


It is worthy of noting that the contractors' representatives in this project are given the

title of "Supervisors" because they were the representatives of their companies in site,

and there were no engineers representing the contractors in site.


The interviews were held during the period of 22 to 26 December 2009 and conducted

with each participant separately for a duration of sixty to ninety minutes.




                                             38
                        4 RESULTS AND DISCUSSIONS



This chapter presents the results of the study, their analysis, and interpretations.

It is divided into three sections, the first section covers the severity of rework by work

category, the second presents the rework causes, and the final section presents the impact

of rework on different parameters of project performance.



4.1 Severity of Rework


This section presents the severity of rework by different work categories and its ranks as

seen by the different project participants. Severity of rework is measured by its

frequency.


Table 4.1. contains the frequency of rework by different work categories as assessed by

the representatives of the owner, the consultant, and the contractors.

The table shows the average frequency of rework for each work category, and is depicted

graphically in Figure 4.1. As noted in the table, while the representative of the owner and

one engineer of the consultant assessed the rework frequencies for all work categories,

the assessment of the contractors' representatives as well as for some of the consultant

representatives is only for some work categories. This is due to the different work scope

of the contractors as well as of the consultant.


Table 4.2 rank orders the work categories according to their average frequency of rework.




                                              39
Table 4.1 Average Rework Frequency* by Work Category


 Category                                                                                                                                                     Fire
                                   Waterproofing                      Flooring
Description   Reinforced                                                           False                Aluminium                              Air        protection
                           Block    and thermal    Plaster   Screed   and wall               Painting                Wooden   Electrical                               Plumbing   Elevators
     /         concrete                                                           ceiling                and glass                         conditioning    and fire
                           works     insulation    works     works    cladding                works                   works     works                                    works      works
Participant     works                                                             works                   works                               works        fighting
                                       works                           works
   Type                                                                                                                                                     works



                                                                                 Frequency of rework
  Owner        1.00        3.00       0.00         2.00      0.00     2.00        0.00       0.00        2.00        0.00      1.00          1.00          0.00         1.00       0.00
Consultant
    A          2.00        3.00       0.00         2.00      0.00     2.00        1.00       0.00        3.00        0.00      1.00          1.00          0.00         1.00       0.00
Contractor
    A          2.00        3.00       0.00         2.00      0.00     1.00        1.00       0.00                              1.00                                                0.00
Contractor
    B                                                                                                    2.00
Consultant
    B                                                                                                                          2.00                        1.00
Consultant
    C                                                                                                                                        1.00          1.00         2.00
Contractor
    F                                                                                                                                                                              1.00
Contractor
    C                                                                                                                                                                   2.00
Contractor
    E                                                                                                                1.00
Contractor
    D                                                                                                                                                      1.00
 Average
Frequency      1.67        3.00       0.00         2.00      0.00     1.67        0.67       0.00        2.33        0.33      1.25          1.00          0.50         1.33       0.25
of rework




*Based on frequency scale of 0,1,2,3,4 representing never, rarely, sometimes, often, and always respectively




                                                                                            40
                         3.00

                                                                                     2.33
                                          2.00
                 1.67                                      1.67
                                                                                                      1.25                 1.33
                                                                                                             1.00
                                                                    0.67
                                                                                                                    0.50
                                                                                              0.33                                0.25
                                  0.00             0.00                     0.00




Figure 4.1 Average Frequency of Rework by Work Category

Note: Frequency scale of 0,1,2,3,4 representing never, rarely, sometimes, often, and always respectively



                                                                       41
Table 4.2 Rank Order of Work Categories According to Their Rework Frequencies *

                                  Average
      Work Category              Frequency         Ranking
                                 of Rework
        Block works                 3.00              1
    Aluminum and glass
                                      2.33            2
            works
        Plaster works                 2.00            3
 Reinforced concrete works            1.67            4
 Flooring and wall cladding
                                      1.67            4
            works
      Plumbing works                  1.33            5
      Electrical works                1.25            6
   Air conditioning works             1.00            7
     False ceiling works              0.67            8
   Fire protection and fire
                                      0.50            9
       fighting works
       Wooden works                   0.33            10
       Elevators works                0.25            11

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.


The data on individual work categories show that these categories ranged between 2.00 to

3.00. These work categories are block works with the highest average of 3.00 followed

by aluminum and glass works with an average of 2.33, then plaster works with an

average of 2.00. This means that these three work categories underwent rework from

sometime to often.


For the next four work categories which are reinforced concrete works, flooring and wall

cladding works, plumbing works, and electrical works, the average frequency of rework

was between1.25 to 1.67. That means that rework was happening for those work

categories little more that rarely.



                                              42
And for the next five work categories which are wooden works, fire fighting and fire

protection works, false ceiling works, air conditioning works, and elevators works, the

average was between 0.25 to 1.00 which means that occurrences of rework for those

categories was rarely and less.


Rework never happened to waterproofing and thermal insulation works, screed works,

and painting works.



4.1.1 Discussion of Severity of Rework


This section interprets the data presented in the previous section, and proposes some

measures to reduce or minimize rework frequency.


Two general observations can be made about the data in Table 4.1. The first observation

is the relative consistency of the respondents regarding the severity of rework in each

work category. As noted, the maximum difference between respondents' assessment is

one frequency point. This provides some indication of the reliability of the data. The

second general observation is the reactive moderate frequency of rework, where the

frequency averages ranged between0.00 to 3.00 with the overall average across all work

categories is 1.07.


For individual work categories, and as mentioned earlier, the work categories of block

works, aluminum and glass works, and plaster works experienced the most frequent

rework between 2.00 to 3.00.When the interviewees were asked about the circumstances

of the execution of different work categories, it was revealed that in the time of executing

block works there were no quality measures. It was only after executing almost 75% of

                                            43
the works, it was discovered that there were many defects, such as missing tie beams in

the middle of already constructed 4.55 meters high block walls.


Also there were some problems in the plumpness of the walls. Some walls in the project

were curved walls and they were wrongly implemented, i.e. not following the curvature

as per drawings. All of those problems lead to the relatively high rework frequency.


Related to the relatively high frequency of rework for the aluminum and glass works, it

was explained by contractor B (supervisor of aluminum and glass contractor) that the

contractor assigned this work to a subcontractor which was disclosed by the

subcontractor himself that his specialty was not in curtain walls but rather in aluminum

and glass doors and windows. Many defects were discovered in his work especially in the

construction of the curtain wall structure.


The average frequency of rework in the plaster works also was 2.00 which means that

rework was happening sometimes. That resulted from many factors, contractor A

(supervisor of finishing and electrical works contractor) informed that the instructions

which were given by the construction supervisor to the subcontractors were incorrect,

such as not providing enough curing time for each stage in the plaster works which

resulted in poor bonding as well as weak strength of plaster. Also the non presence of

contractor' supervisors lead workers to not follow proper specifications like not checking

right angles between walls and plumpness of the surface.


Several work categories experienced rework with frequencies averaging between1.00 to

1.67 meaning that rework was happening between rarely and less than sometime. These




                                              44
categories include air conditioning works, electrical works, plumbing works, flooring and

wall cladding works, and reinforced concrete works.


For reinforced concrete works, the frequency of rework was 1.67 which means that

rework was happening for the reinforced concrete works more than rarely and less than

sometime. The owner indicated that the execution of this work category was of poor

quality, the dimensions were not as per drawings and there were some defects in slab

levels. Such problems did not lead to rework to happen for the reinforced concrete works

per se, but it caused rework to occur in other related work categories. Block works was

badly affected by the defects of the reinforced concrete works. For instance, for the

curved walls the masons were following the concrete slab edges and when it was

inspected it was found that most of the curves were wrongly implemented. The same

affected the aluminum and glass works, because when curtain walls (aluminum and glass

works for the external elevations) especially the aluminum structure elements started to

be implemented, the gabs between them and the concrete slabs were variant and their

adjustments were very difficult to be executed, because the aluminum contractor had to

fabricate aluminum brackets of many sizes for the proper adjustments.


For the flooring and wall cladding works, the frequency of rework was 1.67 which means

that rework was happening more than rarely and less than sometime. It was explained by

consultant A (architectural consultant) that two main causes behind rework in this work

category was improper work sequencing and improper work protection. The project

schedule was much delayed and it was decided to start laying flooring tiles before

completing other related work categories such as painting, false ceiling which in turn

caused some damages in tile works. Such damages could have been avoided if the

                                           45
flooring tiles were well protected but the protection measures which were implemented

were not adequate.


The average frequency of rework for the plumbing works was 1.33 which means that

rework occurrence for this work category was happening little more than rarely.


When consultant C (mechanical consultant) was asked about the circumstances of rework

for the plumbing works he mentioned that the supervision for such work category was

insufficient as well as incompetent which caused some problems in the plumbing works

such as the improper position of the bath tab mixers and their alignment with the wall

ceramic tiles.


The average frequency of rework for the electrical works was 1.25 and thus rework was

happening little more than rarely.


Contractor A (supervisor of finishing and electrical contractor) explained that part of the

electrical works was executed by an inexperienced subcontractor who committed many

mistakes such as inserting in conduits more electrical wires than specified as well as

using the wrong color code for the grounding wires which caused part of the electrical

works to be redone.


Regarding the air conditioning works, their average rework frequency was 1.00 which

means that rework was occurring rarely.


When consultant C (mechanical consultant) was asked about the causes of rework for the

air conditioning works and the circumstances he indicated that some of the workmanship

as well as the supervision were incompetent which caused some defects in the works such


                                            46
as not adjusting the positions of the diffusers as well as not properly fixing ducts and

adjusting their levels.


The remaining work categories including false ceiling works, fire fighting and fire

protection works, wooden works, and elevators works, experienced rework frequencies

ranging between 0.25 and 1.00, indicating that rework was happening rarely to less than

rarely.


The average frequency of rework for the false ceiling works was 0.67 which means that

rework was happening less than rarely for this work category.


Consultant A (architectural consultant) stated that there were some little defects in this

work category such as the non – smoothness of the curvature of some of the curved edges

of the false ceiling.


Contractor D (supervisor of fire fighting and fire protection works) cited some secondary

valves being wrongly located in the drawings which caused rework.


The owner stated that the very early installation of the wooden doors as well as the poor

protection resulted in some scratches and some damages to the doors hardware which

leads to rework. The poor quality of reinforced concrete lead to some extra work for the

preparation for the elevators works.


The average frequency of rework for elevators works was 0.25 which means that the

rework was occurring less than rarely for this work category.




                                           47
Contractor F (supervisor of elevators contractor) stated that because of good

workmanship, very little defects happened in works such as not adjusting the position of

the thresholds of the elevators' doors.


For waterproofing and thermal insulation works, screed works, and painting works,

rework never happened. Waterproofing and thermal insulation works were done by a

specialty contractor and it was well done. The contractor was implementing quality

control measures and the works were frequently inspected and works were delivered on

schedule. Screed works had faced some problems in thickness because of defects in

levels of reinforced concrete works and the contractor had incurred extra cost because of

adding some extra reinforcement in the wire mesh and concrete thickness, but the work

was done properly. Only some schedule delays incurred to painting works, but no rework

happened.


In some of the construction projects, the frequency of rework may be high for work

categories such as plumbing, electrical, air conditioning works, because of the lack of

coordination. But in this case study the average frequency of rework for such work

categories were between0.25 to 1.50 which seems to be reasonable frequency.


Two possible reasons for this low frequency were suggested by the owner. The first

reason was that, a mock up had been executed including air conditioning, electrical, fire

protection and fire fighting, plumbing, false ceiling, painting, and flooring tiles works.

Modifications were done in that mock up which resulted in reducing rework for those

work categories. Another reason was the generous clearance of one meter under each

ceiling which provided comfortable space for installing the air conditioning ducting


                                           48
system, electrical conduits, and fire fighting and plumbing pipes. Moreover, consultant A

(architectural consultant) referred the low rework frequencies for air conditioning,

plumbing, and fire fighting and fire protection works to the fact that the contractors of

these work categories were specialty contractors and they were more organized and have

special crews for each part of the work which enabled them to lower the defects in their

works and consequently the amount of rework.


Consultant A (architectural consultant) proposed that for reducing rework, the consultant

must review and revise carefully the contractor’s submittals such as material submittals,

quality control and quality assurance plans, submittals schedule, etc.



4.2 Rework Causes


The interview questions contained some choices of rework causes for the interviewees to

choose from, also they were requested to specify other causes if any, and to indicate the

frequency for each rework cause for each work category. The choices of rework causes

presented to the interviewees included poor workmanship, insufficient supervision,

incompetent supervision, wrong material, wrong equipment, defective material, defective

equipment, errors and omissions in drawings, client's change, and others to specify if

there are any other causes. The respondents added some other causes such as deviation

from drawings, improper subcontractor selection, improper work protection, lack of

coordination, and improper work sequencing.




                                            49
The interviewees were asked to indicate the frequency of rework causes on the project

level and for each work category using the frequency scale of 0, 1, 2, 3, and 4

representing never, rarely, sometime, often and always respectively.



4.2.1 Average Frequency of Rework Causes on Work Categories


As shown in Table 4.3 the pervasiveness of rework causes differs dramatically. While

some causes affect almost all work categories, other causes are limited to few work

categories.   Rework causes affecting ten to eleven work categories include poor

workmanship, insufficient supervision, and incompetent supervision and their average

rework frequencies ranging between 1.00 to 4.00 which means that these rework causes

were happening between rarely to always to different work categories. Whereas, the

remaining rework causes affecting between one to three work categories include wrong

material, defective material, errors and omissions in drawings, deviations from drawings,

improper subcontractor selection, improper work sequencing, improper work protection,

and lack of coordination. The average frequencies of these rework causes also range

between 1.00 to 4.00 which means that these rework causes were happening from rarely

to always to the different work categories.

From the above observations, the rework causes can be classified into two categories, the

first category is the rework causes that affecting many work categories, and the second

category is the rework causes that affecting few work categories.




                                              50
Table 4.3 Average Frequencies* of Rework Causes / Work Categories


                                                                                 Rework Causes



                                                                                          Errors and
  Work                                                                                    omissions    Deviations     Improper       Improper    Improper
                     Poor       Insufficient   Incompetent    Wrong      Defective            in         from       subcontractor      work        work         Lack of
Categories       workmanship    supervision     supervision   material   material          drawings    drawings       selection     sequencing   protection   coordination

 Reinforced
  concrete              3.00          3.33           3.67                                                  3.00
    Block               3.00          3.00           4.00                                                  3.00
   Plaster              2.33          2.33           2.67
Flooring and
wall cladding           1.33          1.67           2.33                                                                  2.00          4.00        3.00
False ceiling                         1.00                                  1.00
   Painting
  Aluminum
  and glass             2.33          2.00           4.00       2.00                                                       2.00
   Wooden                                                                                                                                2.00
  Electrical            1.25          1.33           1.75       2.00                                                       2.00
     Air
conditioning            1.50          1.50           2.00
     Fire
 protection
  and fire
  fighting              1.00          1.00           1.00                                     2.00                                                                  2.00
  Plumbing              1.75          2.25           2.50                   2.00                                                                     3.00           3.00
  Elevators             2.00          1.00           1.00

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively.



                                                                                     51
4.2.1.1 Rework Causes Affecting Many Work Categories


There were three rework causes that affected ten to eleven work categories and they are

insufficient supervision, incompetent supervision, and poor workmanship, and all of them

are direct rework causes.



4.2.1.1.1 Insufficient Supervision


Insufficient supervision is a direct rework cause. As shown in Figure 4.2 and Table 4.4,

insufficient supervision as a rework cause affected 11 work categories. Its frequency on

different work categories varies from one category to another.


As shown in Table 4.4 insufficient supervision was happening often in reinforced

concrete works, and block works and its frequency was 3.33 and 3.00 respectively.


The occurrences of insufficient supervision were happening sometimes to plaster works,

plumbing works, aluminum and glass works, and flooring and wall cladding works with

average frequencies of 2.33, 2.25, 2.00, and 1.75 respectively.


Insufficient supervision was happening to air conditioning works, and electrical works

with average frequencies of 1.00, and 0.75 respectively.


It almost never happened to fire fighting and fire protection works, false ceiling works,

and elevators works and its average frequencies of previous work categories were 0.40,

0.33 and 0.25 respectively.




                                            52
Figure 4.2 Average Frequency of Insufficient Supervision on Different Work Categories

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively




                                                                       53
 Table 4.4 Average Frequency* of Insufficient Supervision on Different Work Categories


                                                                                              Fire
                                       Flooring
              Reinforced                         False Aluminium                 Air      protection
                         Block Plaster and wall                   Electrical                         Plumbing Elevators
               concrete                         ceiling and glass            conditioning  and fire
                         works works cladding                       works                              works    works
                works                           works    works                  works      fighting
                                        works
                                                                                            works
   Owner           4          4        2         2         0          1            2            2                0      3      0
 Consultant
                   4          4        4         2         1          1            0            0                0      3      0
      A
 Contractor
                   2          1        1         1         0                       0
      A
 Contractor
                                                                      4
      B
 Consultant
                                                                                   1                             1
      B
 Consultant
                                                                                                1                1      2      0
      C
 Contractor
                                                                                                                               1
      F
 Contractor
                                                                                                                        1
      C
 Contractor
                                                                                                                 0
      D
  Average
 frequency
                 3.33       3.00     2.33       1.67      0.33       2.00        0.75          1.00             0.40   2.25   0.25
 of rework
   cause

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively



                                                                          54
4.2.1.1.1.1 Discussion of Insufficient Supervision


The average frequency of insufficient supervision was between0.25 to 0.40 for fire

fighting and fire protection, elevators, and false ceiling works, because the contractor of

the fire fighting and elevators works were specialty contractors and their supervisors were

present on site most of the time. The same for the false ceiling works, the subcontractor

of the false ceiling works was a specialty subcontractor and his supervisor was present on

the site mostly all the time.


For the electrical, air conditioning, and flooring and wall cladding works the frequencies

of insufficient supervision rework cause were between 0.75 to 1.67 which means that this

rework cause was happening from less than rarely to less than sometimes. That was due

to presence of their supervisors.


The average frequency of the insufficient supervision for some work categories such as

reinforced concrete, block, plaster, plumbing, and aluminum and glass works was

between 2.00 to 3.33 which are relatively high. That was because the rare presence of

their supervisors. The interviews revealed further information on this issue and provided

some examples.


In the reinforced concrete works, the owner explained that the insufficient supervision

lead to not checking the levels of the foreman of slabs before concrete pouring which

lead to differences in slab levels.


In the block works, the owner also revealed that the inadequate supervision lead to not

checking the quality measures which might be implemented to block works like the limits

                                            55
of the executed height of block works per day, as well as the steel angles to be fixed

between block and concrete columns.


In the plaster works, consultant A (Architectural consultant) stated that the insufficient

supervision affected the quality of the works such as, sometimes the workers were adding

gypsum to the mortar mixture to get dried quickly, or not fixing wire mesh between

columns, beams and blocks.


In the plumbing works, contractor C (supervisor of plumbing contractor) suggested that

the insufficient supervision gave the workers the opportunity of not following the quality

control procedures in fixing the fittings between pipes, which resulted in rework.


It was stated by contractor B (supervisor of aluminum and glass contractor) in the

aluminum and glass works that the non availability of supervisor gave the workers the

chance to bypass steps in work, such as leaving gaps between the aluminum elements

which lead to dismantling the elements and resulted in rework.


Consultant A (Architectural consultant) said that the insufficient supervision lead in the

flooring and wall cladding works to not curing the flooring tiles works with water which

lead to poor bonding in some of the tiles works which resulted in rework.


Consultant C (mechanical consultant) suggested in the air conditioning works that the

insufficient supervision caused the technicians to improperly tie the joints of the ducts,

which caused leakage in the ducts and resulted in rework.


In the electrical works, consultant B (electrical consultant) explained that inadequate

supervision caused the electricians to use the wrong color code for the earth wiring.


                                            56
The insufficiency of supervisors caused rework to happen in this case study, but it was

not a frequent cause of rework in previous rework studies. Such rework cause could be

reduced or minimized by the owner requiring and enforcing the continuous presence of

supervisors in the project.



4.2.1.1.2 Incompetent Supervision


As shown in Table 4.5 incompetent supervision as a rework cause affected 11 work

categories. Its frequency on different work categories varies from one category to

another. As shown in Figure 4.3 incompetent supervision was happening almost always

in block works, aluminum and glass works, reinforced concrete works, and plaster works

with average frequencies of 4.00, 4.00, 3.67, and 3.33 respectively.


The occurrences of incompetent supervision were sometimes to plumbing works, flooring

and wall cladding works, air conditioning works, and electrical works with average

frequencies of 2.50, 2.33, 2.00, and 1.75 respectively.


It almost never happened to fire protection and fire fighting works, false ceiling works,

and elevators works with average frequencies of 0.40, 0.33, and 0.25 respectively.



4.2.1.1.2.1 Discussion of Incompetent Supervision


The severity of this rework cause was very limited for the fire protection and fire

fighting works, false ceiling works, and elevators works with averages 0.40, 0.33, and

0.25. The owner informed that the supervision for these work categories was competent,



                                            57
Table 4.5 Average Frequency* of Incompetent Supervision on Different Work Categories



                                                                                                Fire
                                         Flooring
                Reinforced                         False Aluminium                 Air      protection
                           Block Plaster and wall                   Electrical                         Plumbing Elevators
                 concrete                         ceiling and glass            conditioning  and fire
                           works works cladding                       works                              works    works
                  works                           works    works                  works      fighting
                                          works
                                                                                              works
    Owner           4        4         4         2         0          4            2            2                0    2      0
  Consultant
      A
                    4        4         3         3         1          4            2            2                0    4      0
  Contractor
      A
                    3        4         3         2         0                       1
  Contractor
      B
                                                                      4
  Consultant
      B
                                                                                   2                             1
  Consultant
      C
                                                                                                2                1    3      0
 Contractor F                                                                                                                1
 Contractor
     C
                                                                                                                      1
 Contractor
     D
 Contractor E                                                                                                    0
   Average
  frequency
  of rework
                  3.67      4.00     3.33      2.33      0.33       4.00         1.75          2.00          0.40    2.50   0.25
    cause

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively.



                                                                          58
                   4.00                                               4.00
       3.67
                                3.33


                                                                                                                         2.5
                                            2.33
                                                                                                  2
                                                                                  1.75




                                                         0.33                                                0.4
                                                                                                                                    0.25


    Reinforced Block works Plaster works Flooring and False ceiling Aluminum    Electrical       Air          Fire     Plumbing   Elevators
     concrete                           wall cladding    works      and glass     works      conditioning protection     works      works
      works                                 works                     works                     works      and fire
                                                                                                           fighting
                                                                                                            works




Figure 4.3 Average Frequency* of Incompetent Supervision on Different Work Categories

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively.




                                                                         59
two of these work categories were specialty contractors, fire fighting and fire protection

works and elevators works were specialty contractors, also the subcontractor of the false

ceiling works was specialty contractor and his supervisors were competent.


The severity of incompetent supervision was moderate in plumbing works, flooring and

wall cladding works, air conditioning works, and electrical works with average

frequencies of 2.5, 2.33, 2.00, and 1.75 respectively, and this can be explained by the

mediocre skills and the experiences of the supervisors of these work categories thus

causing some defective work as will be illustrated by the examples in this section.


The severity of incompetent supervision was high in block works, aluminum and glass

works, reinforced concrete works, and plaster works with average frequencies of 4.00,

4.00, 3.67, and 3.33 respectively because of the unskilled supervisors of these work

categories.


The interviewees provided information on the circumstances and some examples of

incompetent supervision on block works, aluminum and glass works, reinforced concrete

works, and plaster works.


In block works, the owner stated that the average floor to floor height according to the

shop drawings was 4.55 meters, the supervisors did not properly read the comments on

drawings and their requirements, that after 2.5 meters height of blocks, a reinforced

concrete tie beam should be placed before completing the full height of blocks. Ignoring

these requirements resulted in the full height was completed with blocks without

incorporating the tie beam, which resulted in demolishing the upper half of the block

walls to build the tie beams.


                                            60
It was explained by contractor B (supervisor of aluminum and glass contractor) that in

aluminum and glass works, the supervisor did not adjust the plumpness of the main

vertical supports of the main structure of the curtain wall, as well as the level of the main

horizontal supports (transoms), which all resulted in dismantling of a big part of the

structure to adjust the level and the plumpness.


The owner suggested that in the reinforced concrete works, the supervisor did not have

sufficient skills to properly implement the correct curvatures of the reinforced border

beams as well as the curvatures of the stepped inner border beams of the patio, which

resulted in defective works and consequently lead to rework.


Contractor A (supervisor of finishing and electrical contractor) informed that in the

plaster works, the supervisor did not have the experience needed for adjusting the

curvature of the walls in the plaster works, which lead to frequent rework.


The following are some examples of the incompetent supervision which happened

sometimes to plumbing works, flooring and wall cladding works, air conditioning works,

and electrical works.


Contractor C (supervisor of plumbing contractor) stated that in the plumbing works, the

wrong positioning of some of the waste drain of water closets as well as the floor drains

resulted in their rework.


Consultant C (mechanical consultant) stated that in the air conditioning works, the

supervisor did not properly position the diffusers which caused rework.




                                             61
In the electrical works, consultant B (electrical consultant) indicated that the supervisor

did not have the required knowledge to determine the number of wires which must be in

the different conduit sizes, which lead to rework.


The non availability of the skilled and experienced supervisors causes the incompetent

supervision to happen and its average frequency varied form work category to another,

and it was a frequent cause of rework as it was revealed by previous rework studies. Such

rework cause could be reduced or minimized by application of training programs, and

adoption of frequent evaluation system of the skills and knowledge of the supervisors.



4.2.1.1.3 Poor Workmanship


As shown in Figure 4.4, poor workmanship as a rework cause affected 10 work

categories. Its frequency on different work categories varies from one category to

another. As shown in Table 4.6, poor workmanship was happening often in reinforced

concrete works, and block works and its average frequency was 3.00 for both work

categories.


The occurrences of poor workmanship were sometimes to plaster works, aluminum and

glass works, and plumbing works with average frequencies of 2.33, 2.33, and 1.75

respectively.


It almost never happened in elevators works, and fire protection and fire fighting works

as their average frequencies were 0.50, and 0.40 respectively.




                                            62
      3.00          3.00



                                 2.33                       2.33



                                                                                                                       1.75

                                               1.33
                                                                            1.25
                                                                                          1


                                                                                                                                  0.5
                                                                                                         0.4




   Reinforced   Block works Plaster works Flooring and Aluminum and     Electrical       Air              Fire       Plumbing   Elevaors
    concrete                              wall cladding glass works       works      conditioning     protection       works     works
     works                                   works                                      works           and fire
                                                                                                    fighting works




Figure 4.4 Average Frequency* of Poor Workmanship on Different Work Categories

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively




                                                                       63
 Table 4.6 Average Frequency* of Poor Workmanship on Different Work Categories

                                                                                       Fire
                                       Flooring
              Reinforced                        Aluminium                 Air      protection
                         Block Plaster and wall            Electrical                         Plumbing Elevators
               concrete                          and glass            conditioning  and fire
                         works works cladding                works                              works    works
                works                             works                  works      fighting
                                        works
                                                                                     works
   Owner          2          2        3          1           1           1             1             0            1      0
 Consultant
     A
                  4          4        2          2           3           1             0             0            2      0
 Contractor
     A
                  3          3        2          1                       1
 Contractor
     B
                                                             3
 Consultant
     B
                                                                         2                           1
 Consultant
     C
                                                                                       2             1            2      0
 Contractor
     F
                                                                                                                         2
 Contractor
     C
                                                                                                                  2
 Contractor
     D
                                                                                                     0
  Average
 frequency
                 3.00       3.00     2.33      1.33        2.33         1.25         1.00          0.40          1.75   0.50
 of rework
   cause

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always respectively.




                                                                        64
4.2.1.1.3.1Discussion of Poor Workmanship


The average frequencies of the poor workmanship are a reflection of the skills and

experience of the workers. For instance, the skills and experience of the workers of the

reinforced concrete works and block works were very low and the average frequencies of

poor workmanship of these work categories were 3.00 which means that this cause was

happening often for these work categories. The opposite was the case of the air

conditioning, elevators, and fire fighting and fire protection works. The average

frequencies of poor workmanship were 1.00, 0.50, and 0.40 respectively and the skills

and the experiences of their workers were relatively high.


The interviewees provided information on the circumstances and some examples of poor

workmanship on plaster works, aluminum and glass works, and plumbing.


Consultant A (architectural consultant) stated that in the plaster works, the workmanship

was poor, due to workers' failure to properly cure the first coat of the plaster before

applying the final coat of the plaster, which lead to cracks in plaster and resulted in

rework.


It was mentioned by contractor B (supervisor of aluminum and glass contractor) that in

the aluminum and glass works, workers did not have the skills to properly fix the brackets

used in fixing the aluminum vertical supports with the concrete slabs and beams which

lead to rework.




                                            65
In the plumbing works, consultant C (mechanical consultant) informed that workers were

not properly adjusting the positions and levels of the bathtub mixers, as well as the sinks

mixers.


Although the poor workmanship was happening almost rarely to flooring and wall

cladding works, electrical works, and air conditioning works, some defects were noted in

the flooring tiles works as it was suggested by consultant A (architectural consultant),

such as poor adjustment and leveling of the tiles. For the electrical works, consultant B

(electrical consultant), stated that some errors were happening from workers like not

properly adjusting the surface of the outlet boxes with the wall surface, as well as not

adjusting their proper levels. Also for the air condition works, consultant C (mechanical

consultant) informed that workers were not properly fixing the drain pipes of the air

condition system.


The non availability of the skilled and experienced workers causes the poor workmanship

to happen and its average frequency varied form work category to another, and it was a

frequent cause of rework as it was revealed by previous rework studies. Such rework

cause could be reduced or minimized by careful recruitment of workers, application of

training programs, and adoption of frequent evaluation system of the skills and

knowledge of the workers.



4.2.1.2 Rework Causes Affected Few Work Categories


There were eight rework causes that affected between one to three work categories

including improper subcontractor selection, improper work protection, wrong material,


                                            66
defective material, deviations from drawings, improper work sequencing, lack of

coordination, and errors and omissions in drawings. Some of these are direct rework

causes, and others are indirect rework causes.



4.2.1.2.1 Improper Subcontractor Selection


Improper subcontractor selection is an indirect rework cause because it may indirectly

cause rework.


As shown in the Table 4.7 the improper subcontractor selection as an indirect cause of

rework affected four work categories, flooring and wall cladding works, aluminum and

glass works, electrical works, and plumbing works.


The improper subcontractor selection was happening sometime to flooring and wall

cladding works, aluminum and glass works, and electrical works with average

frequencies of 2.00, 2.00, and 1.67 respectively. And it was happening to plumbing

works rarely with an average frequency of 1.00.



4.2.1.2.1.1 Discussion of Improper Subcontractor Selection


Only five out of ten respondents mentioned that improper subcontractor selection was

rework cause.


There were three contractors employing subcontractors, for reinforced concrete works,

block works, plaster works, aluminum and glass works, plumbing works, flooring and

wall cladding works, and electrical works. Only four work categories were affected by



                                            67
the improper subcontractor selection, other work categories were not affected by this

rework cause.


Table 4.7 Average Frequency* of Improper Subcontractor Selection



                Flooring
                         Aluminium
                and wall            Electrical Plumbing
                          and glass
                cladding              works      works
                           works
                 works

    Owner                     1           1
 Consultant A                             2           1
 Contractor A      2
 Contractor B                 3
 Consultant B                              2
   Average
  frequency
                2.00        2.00         1.67        1.00
  of rework
    cause
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.



The average frequencies of improper subcontractor selection were between 1.00 to 2.00

which means that this cause happened rarely to sometimes to these four work categories

and its severity was depending on the size of defective works caused by the

subcontractors. The interviews revealed further information on this issue and provided

some examples.


Consultant A (architectural consultant) stated that in the flooring and wall cladding

works, improper subcontractor selection had contributed to rework because many defects

were discovered from the subcontractor works especially in the flooring tiles installation,

such as non alignment of tiles joints, the varying joints widths between tiles, the non

conformity to the finish floor level, and the hollow- sounded tiles.

                                              68
Contractor B (supervisor of aluminum and glass contractor) informed that in the

aluminum and glass works, improper subcontractor selection was a major problem in this

work category where many defects were found in subcontractor’s works such as the non

plumpness of the main vertical supports of the curtain walls, the non conformity to the

required levels of the horizontal supports of the curtain wall, and the improper anchoring

of the supports to the concrete slabs and beams. It was disclosed by the subcontractor

himself that his specialty was only in aluminum doors and windows not aluminum and

glass curtain wall claddings.


Consultant B (electrical consultant) suggested that in the electrical works, improper

subcontractor selection caused some defects in the electrical works and the major

problem was inserting too many wires in the conduits, as well as using the wrong color

codes.


It was commented by consultant C (mechanical consultant) that in the plumbing works,

improper subcontractor selection caused many defects in the plumbing works such as

wrong locations of floor drains and clean outs, as well as wrong levels of the water

supply connections to the mixers of the bathtub and kitchen sinks and bathroom

lavatories.


To reduce or minimize the improper subcontractor selection, subcontractor's performance

in previous projects should be checked to ascertain his adequacy. The contractor should

utilize an effective system of evaluating subcontractors before their selection, including

price, technical know-how, quality, and cooperation (Hartmann, et al, 2009).




                                           69
4.2.1.2.2 Improper Work Protection


As shown in Table 4.8, improper work protection affected three work categories

including flooring and wall cladding works, plumbing works, and wooden works, with

average frequencies of 3.00, 3.00, and 2.00 respectively.


Table 4.8, Average Frequency* of Improper Work Protection



                Flooring
                and wall Wooden Plumbing
                cladding  works   works
                 works

 Consultant A     3
 Contractor A     3
 Contractor C                           3
 Contractor E               2
    Average
 frequency of
    rework
                 3.00      2.00       3.00
     cause
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.



4.2.1.2.2.1 Discussion of Improper Work Protection


Only four out of ten respondents indicated that improper work protection caused rework

in the above mentioned work categories. The severity of this rework cause was between

2.00 to 3.00 which means that it was happening from sometime to often for the work

categories.


The respondents provided examples of how improper work protection caused rework




                                              70
In the flooring and wall cladding works, consultant A (architectural consultant)

suggested that the improper work protection for the flooring tiles caused some to be

hollow- sounded and others to get scratched which resulted in rework.


In the plumbing works, contractor C (supervisor of plumbing contractor) commented that

many of the floor drain covers, the bath drain covers, and the drain covers of the kitchen

sinks had been damaged or broken because they were installed too early and were not

protected and that caused rework to incur, as well as to supply such accessories one more

time.


In the wooden works, contractor E (supervisor of wood works contractor) stated that

most of the architraves, jambs, and doors were subjected to spots of paints, scratches, and

sometimes breakage, which all resulted in rework.


Such improper work protection was expected to happen in the case study, because as it

was explained by the owner that several prime contractors were involved in his project

and each contractor was primarily handing over his work after finishing it and protecting

it immediately, thereafter without follow up to ascertain the protection is in undisturbed.

Works of the project are finished with many contractors in the project and it was very

difficult from each contractor after finishing his works to properly protect the works till

the primary handing over.



4.2.1.2.3 Lack of Coordination


As shown in Table 4.9, lack of coordination as a rework cause affected two work

categories plumbing works, and fire protection and fire fighting works with average

                                             71
frequencies of 3.00 and 2.00 respectively which means that this rework cause was

happening between sometimes to often to these work categories.


Table 4.9, Average Frequency* of Lack of Coordination


                    Fire
                protection
                             Plumbing
                 and fire
                               works
                 fighting
                  works
 Consultant C       2
 Contractor C                    3
 Contractor D       2
    Average
 frequency of
                  2.00         3.00
    rework
     cause
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.


4.2.1.2.3.1 Discussion of Lack of Coordination


Only three out of ten respondents mentioned that lack of coordination caused rework, in

the above two mentioned work categories. The respondents provided examples of how

lack of coordination caused rework.


Contractor C (supervisor of plumbing contractor) stated that in the plumbing works,

because of the non availability of the coordination drawings which should include all

interrelated work categories such as fire fighting pipes, plumbing pipes, air conditioning

ducts, and electrical conduits, after installation of the riser waste pipes it was discovered

that it was conflicting with the risers of the ducting system of the air conditioning works,

and there was not enough space in the shafts which caused rework for the plumbing

works.

                                              72
Consultant C (mechanical consultant) indicated that in the fire fighting and fire

protection works, the contractor relocated the positions of the main valves in many floors

because they were in conflict with the ducting system.


The lack of coordination as a rework cause was expected to happen in the case study

because of the non availability of the coordination drawings as well as the presence of

several contractors in the case study project without proper coordination among them.


To reduce or minimize the lack of coordination as a rework cause it is recommended to

ascertain the availability of coordination drawings.



4.2.1.2.4 Wrong Material


As shown in Table 4.10, the wrong material as a direct rework cause affected only two

work categories and they are aluminum and glass works, and electrical works with

frequency of 2.00 which means that wrong material was used sometimes in those two

work categories.


4.2.1.2.4.1 Discussion of Wrong Material


Only two out of ten respondents indicated that wrong material caused rework, in the two

mentioned work categories in Table 4.10, the respondents provided examples of how

wrong material caused rework.




                                            73
Table 4.10, Frequency* of Wrong Material


               Aluminium
                         Electrical
               and glass
                         works
               works
 Contractor
                            2
 A
 Contractor
              2
 B
 Frequency
 of rework 2.00             2.00
 cause
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.



Contractor B (supervisor of aluminum and glass contractor) stated that the in aluminum

and glass works the installation of wrong color aluminum cladding in some areas lead to

the dismantling of those claddings and the reinstallation of the correct materials.


Consultant B (electrical consultant) indicated that in the electrical works, the wrong

wiring color was used in part of the conduits and resulted in rework.


Comparing to previous studies in rework, very little research suggested that wrong

material was a cause of rework. Josephson et al. (2002) proposed that wrong material was

causing rework but with very rare frequency.


Reducing or minimizing the usage of wrong material in construction projects, could be

achieved by checking the site delivered material more than one time, and by different

entities, such as inspecting the material by the contractor’s supervisor, and by the store

keeper, then by the field inspector before installation.




                                              74
4.2.1.2.5 Defective Material


As shown in Table 4.11, the defective material as a direct cause of rework occurred to

two work categories, false ceiling works, and plumbing works, with average frequencies

of 1.00 and 2.00 respectively, which means that it was happening sometimes to plumbing

works, and rarely to false ceiling works.


Table 4.11, Frequency* of Defective Material


                 False
                          Plumbing
                ceiling
                            works
                works
  Contractor
                 1
        A
  Contractor
                            2
        C
  Frequency
   of rework    1.00      2.00
     cause
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.




4.2.1.2.5.1 Discussion on Defective Material


Two out of the ten respondents informed that defective material as a rework cause

resulted in rework, in the above mentioned work categories. The limited presence of

defective material was primarily due to the frequent inspection done by the field

inspectors. The two respondents provided examples of how the defective material caused

rework.




                                              75
Consultant C (mechanical consultant) responded that in the plumbing works, the flexible

ties were not the approved material and when the field inspector was inspecting works

they were leaking.


Contractor A (supervisor of finishing and electrical contractor) informed that in the false

ceiling works, the contractor delivered and installed gypsum panels different from the

approved material in some areas without informing the consultant.


Comparing to previous research rework studies, only one study through the literature

review proposed that faulty manufactured material was causing rework (Josephson et al.

2002).


Defective material as a rework cause may be reduced or minimized in construction

projects by implementing quality control measures such as inspecting materials when

delivered to site by different entities such as contractor’s supervisor, store keeper, and

field supervisor.



4.2.1.2.6 Deviations from Drawings


As shown in Table 4.12, the deviations from drawings as a direct cause of rework
affected only two work categories, reinforced concrete works and block works. Its
average frequency on these two work categories were 3.00 on both, which means that this
cause was happening often.




                                            76
Table 4.12, Average Frequency of Deviations from Drawings


                     Reinforced concrete works        Block works

 Owner               3                                3
 Consultant A        3
 Contractor A        3                                3
 Average frequency
 of rework cause
                     3.00                             3.00
*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.


4.2.1.2.6.1 Discussion of Deviations from Drawings


Three out of ten respondents informed that deviations from drawings caused rework in

the above two work categories. The respondents attributed the deviations in these two

work categories to the improper implementation of quality control during some stages of

the project.


The respondents provided some examples of how deviations from drawings caused

rework. In the block works, the owner reiterated that deviations from drawings especially

for the curved walls constituted the main reason for rework in these walls.


Deviations from drawings were expected to happen in the case study because of the

insufficient control of quality procedures that were implemented in that duration of the

construction of the project.


To reduce or minimize this cause to happen in similar construction projects, supervision

is very crucial to ascertain the compliance of the executed works to the drawings, as well




                                                 77
as the inspection which should be done by the field inspector as well as the contractor's

supervisors.



4.2.1.2.7 Improper Work Sequencing


As shown in Table 4.13 improper work sequencing affected only two work categories,

flooring and wall cladding works, and wooden works, with average frequencies of 4.00

and 2.00 respectively.


Table 4.13, Average Frequency of Improper Work Sequencing




                    Flooring and wall Wooden
                    cladding works    works


 Consultant A                4
 Contractor A                4
 Contractor E                                   2
 Average
 frequency    of           4.00               2.00
 rework cause

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.


4.2.1.2.7.1 Discussion on Improper Work Sequencing

Three out of ten respondents indicated that improper work sequencing caused rework in
the above two mentioned work categories. These respondents provided examples of how
improper work sequencing caused rework.

Consultant A (architectural consultant) responded that in the flooring and wall cladding

works, the improper execution timing caused many defects in flooring tiling works when

                                              78
floor tiles works were completed before the false ceiling works, and painting works. The

frequent usage of scaffold for the false ceiling works as well as for the painting works

caused extensive damage to floor tiles which necessitated rework.


Contractor E (supervisor of wood works contractor) stated that the wood works of the

kitchen cabinets were installed before painting works were finished because installation

timing of the kitchen cabinets per the contract between the owner and the contractor

could not be delayed, and painting works were behind schedule which caused many

defects to happen to kitchen cabinets such as some shelves were broken, some drawers

were broken, and some scratches in the cabinets which all caused rework.


The improper work sequencing also occurred in the floor tiling when the owner ordered

the contractor to start the tiling works before completing other preceding works.


Such rework cause was not explicitly identified by previous rework studies through the

literature review as a factor that caused rework.


The improper work sequencing as a rework cause could be reduced or minimized by

executing each of the work categories in its proper timeframe. This entails the importance

of properly developed and updated construction schedule and the close coordination

between the various trades and contractors.



4.2.1.2.8 Errors and Omissions in Drawings


As shown in Table 4.14, errors and omissions in drawings as rework cause affected only

one work category which is fire protection and fire fighting works.



                                              79
Table 4.14, Frequency* of Errors and Omissions in Drawings




                Fire protection and fire
                fighting works


 Contractor D   2
 Frequency
 of    rework 2.00
 cause

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.


4.2.1.2.8.1 Discussion on Errors and Omissions in Drawings


Only one out of the ten respondent stated that there were errors and omissions in the fire

protection and fire fighting works, thus suggesting this rework cause did not exist in other

work categories.


As an example of the errors and omissions in drawings was provided by contractor D

(supervisor of fire fighting and fire protection contractor) citing some secondary valves

being wrongly located in the drawings and others were missing in the fire fighting works

and that caused rework.


Errors and omissions as a rework cause happened in the case study in only one work

category and its average frequency was sometime.


Comparing to previous rework studies, Love and Smith (2003) proposed that errors in

contract drawings was ranked 2nd among six factors causing rework cost. Josephson et al.




                                              80
(2002) suggested that faulty designs and incomplete drawings were among the main

causes that contributed in rework costs.


To reduce or minimize errors and omissions from happening in contract drawings in

construction projects, several measures can be used including careful development of the

design, quality control of design, design reviews, constructability reviews, and proper

construction planning including contractor's reviewing design.



4.3 The Impact of Rework on Project Performance


Rework has a negative impact on project performance including project cost overrun,

project delays, and the dissatisfaction of the contractor and the client.


The interviewees were asked to indicate what percentage increase in the cost of each

work category due to rework in general, and to indicate percentage of delay due to

rework. Also to indicate any other impact of rework on project performance or

productivity other than cost and time.



4.3.1 Rework Impact on Project Cost


The interviewees' estimates of the percentage increase in the cost of each work category

due to rework are presented in Table 4.15 and in Figure 4.5.


The average increase percent in cost varies from work category to another. As shown in

Table 4.16, the ranking of these averages puts the block works in the 1st place with an




                                              81
Table 4.15 Average Increase in Percent of cost as a Result of Rework



                                                                                                         Fire
                                           Flooring
                Reinforced                           False Aluminium                        Air      protection
                             Block Plaster and wall                   Wooden Electrical                         Plumbing Elevators
                 concrete                           ceiling and glass                   conditioning  and fire
                             works works cladding                      works   works                              works    works
                  works                             works    works                         works      fighting
                                            works
                                                                                                       works
   Owner           3%        40%     15%      30%                10%              2%                               3%
 Consultant A      10%       40%     30%      20%       2%       5%               2%         2%                    5%
 Contractor A      8%        10%     7%       15%       2%                        5%
 Contractor B                                                     5%
 Consultant B                                                                     7%                    2%
 Consultant C                                                                                2%         1%         4%
 Contractor F                                                                                                               2%
 Contractor C                                                                                                      5%
 Contractor E                                                            2%
 Contractor D                                                                                           3%
  Average
 percentage
                   7%        30%     17%      22%       2%        7%     2%       4%         2%         2%         4%       2%
 of increase
   in cost




                                                                82
                         30%




                                           22%


                                  17%




                7%                                            7%
                                                                            4%             4%
                                                     2%                2%        2%   2%        2%




Figure 4.5 Average Increase in Percent of cost as a Result of Rework


                                                                83
Table 4.16, Ranks of Increase in Percent of Cost as a Result of Rework


                                            Average percentage of
             Work category                                           Rank
                                               increase in cost
               Block works                          30%                1
    Flooring and wall cladding works                22%                2
              Plaster works                         17%                3
       Reinforced concrete works                     7%                4
       Aluminium and glass works                     7%                4
             Electrical works                        4%                5
             Plumbing works                          4%                5
           False ceiling works                       2%                6

             Wooden works                            2%                6

         Air conditioning works                      2%                6
  Fire protection and fire fighting works            2%                6
             Elevators works                         2%                6



increase in the cost of 30%, followed by the flooring and wall cladding works in the 2nd

place with an increase in its cost of 22%. In the 3rd place comes the plaster works with an

increase in its cost of 17%. In the 4th place come two work categories, Reinforced

concrete works, and aluminum and glass works with an increase in their cost of 7%. The

electrical and plumbing works come in the 5th place with an increase in their cost of 4%.

The remaining work categories with an average increase in their cost of 2% are false

ceiling works, wooden works, air conditioning works, fire fighting and fire protection

works, and elevators works.




                                              84
4.3.1.1 Discussion of Rework Impact on Project Cost


As shown in Table 4.15, there are large variation in the increase in cost percentages

among the respondents in some work categories including block works, plaster works,

and flooring and wall cladding works. For the block works the owner and consultant A

(architectural consultant) estimated that the percent increase in cost due to rework as

40% where the contractor A (supervisor of finishing and electrical contractor) estimated

the percent as 10%. For the plaster works the owner sated percent as 15%, the consultant

A 30% and contractor A 7%. For the flooring and wall cladding works the owner

indicated 30% increase of rework cost and consultant A 20% and contractor A 15%. This

variation can be partially explained that these percentages were estimates by the

respondents and not exact calculations from project records. Furthermore, it is noticed

that the contractor estimate is always less than the owner's and the consultant's and this

can be interpreted as attempt to down play his role in increasing the project cost.


To investigate the relation between the average frequencies of rework in different

categories and their corresponding percent of increase in cost because of rework, the two

sets of data are presented in Table 4.17.


The Pearson's Correlation coefficient of these two sets of data is 0.822 (significant at

0.01) which indicates strong correlation between the average frequency of rework and the

percent of increase in cost. This is expected since a more frequent rework arises to meet

rework cost.




                                             85
Table 4.17, Average Rework Frequency* of Work Category and Corresponding Increase in Cost

                                               Average
                                             Frequency of            Percent
            Work Category                       Rework           Increase in Cost
               Block works                       3.00                  30%
   Flooring and wall cladding works              1.67                  22%
              Plaster works                      2.00                  17%
      Reinforced concrete works                  1.67                  7%
      Aluminum and glass works                   2.33                  7%
             Electrical works                    1.25                  4%
            Plumbing works                       1.33                  4%
          False ceiling works                    0.67                  2%
             Wooden works                        0.33                  2%
         Air conditioning works                  1.00                  2%
 Fire protection and fire fighting works         0.50                  2%
            Elevators works                      0.25                  2%

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.



4.3.2 Percentage of Delay Due to Rework


The interviewees' estimates of the percentage delay of each work category due to rework

are presented in Table 4.18, and Figure 4.6. It is worth noting that the interviewees were

not asked to provide these data directly but rather indirectly. They were asked to indicate

the original durations of the work categories which experienced rework, and their

estimate of the additional time duration of these work categories as a result of rework and

the writer of this report calculated the percentage of delay due to rework as reported in

Table 4.18.


Table 4.19, ranks of the work categories in a descending order of their delays, aluminum

and glass works comes in the 1st category with an average percentage of delay of 77%


                                              86
Table 4.18 Average Percentage of Delay due to Rework

                                                                                                     Fire
                                       Flooring
              Reinforced                         False Aluminium                        Air      protection
                         Block Plaster and wall                   Wooden Electrical                         Plumbing Elevators
               concrete                         ceiling and glass                   conditioning  and fire
                         works works cladding                      works   works                              works    works
                works                           works    works                         works      fighting
                                        works
                                                                                                   works
   Owner        15%      100%    70%     50%              100%                15%       10%                   20%
 Consultant
                10%      65%     80%     50%     10%      40%                 12%        5%                   50%
     A
 Contractor
                10%      50%     30%     40%     20%                          30%
     A
 Contractor
                                                          90%
     B
 Consultant
                                                                              25%                   10%
     B
 Consultant
                                                                                        20%         10%       25%
     C
 Contractor
                                                                                                                        15%
     F
 Contractor
                                                                                                              20%
     C
 Contractor
                                                                    10%
     E
 Contractor
                                                                                                    10%
     D
  Average
 percentage     12%      72%     60%     47%     15%      77%       10%       21%       12%         10%       29%       15%
  of delay




                                                            87
                                                                  77%
                 72%


                             60%



                                          47%




                                                                                                                           29%

                                                                                         21%
                                                      15%                                                                             15%
      12%                                                                                           12%
                                                                               10%                             10%




   Reinforced Block works   Plaster   Flooring and False ceiling Aluminum     Wooden   Electrical  Air          Fire     Plumbing   Elevaors
    concrete                works         wall        works      and glass     works     works conditioning protection     works     works
     works                              cladding                   works                          works      and fire
                                         works                                                               fighting
                                                                                                              works


Figure 4.6 Average Percentage of Delay due to Rework




                                                                         88
related to rework activities. The block works comes in the 2nd rank with 72% of delay.

Plaster works comes in the 3rd place with 60% delay. In the 4th place the flooring and wall

cladding works is ranked with a percent in delay of 47%. The plumbing works and

electrical works come in the 5th and 6th ranks with average delay percentages of 29% and

21% respectively. False ceiling works and elevators works come in the 7th place with an

average percent of 15% of delay related to rework activities. Reinforced concrete works

and air conditioning works come in the 8th place with average percent of 12% delay. The

last two work categories that are the wooden works and fire protection and fire fighting

works come with an average percent of 10% delay.


Table 4.19 Ranks of Average Percentage of Delay due to Rework


          Work category               Average percentage of      Ranks
                                              delay
    Aluminium and glass works                 77%                  1
            Block works                       72%                  2
           Plaster works                      60%                  3
  Flooring and wall cladding works            47%                  4
          Plumbing works                      29%                  5
         Electrical works                     21%                  6
        False ceiling works                   15%                  7
         Elevators works                      15%                  7
    Reinforced concrete works                 12%                  8
       Air conditioning works                 12%                  8

          Wooden works                        10%                  9
  Fire protection and fire fighting           10%                  9
               works




                                              89
4.3.2.1 Discussion of Percentage of Delay Due to Rework



By comparing the average frequency of rework of different work categories and their

corresponding percent of delay due to rework and as shown in Table 4.20, the increase of

the percent of delay due to rework is directly related to the severity of rework.



Table 4.20, Average Rework Frequency* of Work Category and Corresponding

Percentage of Delay due to Rework


                                                                      Percentage of
                                          Average frequency            delay due to
            Work category                     of rework                  rework
     Aluminum and glass works                    2.33                      77%
              Block works                        3.00                      72%
             Plaster works                       2.00                      60%
  Flooring and wall cladding works               1.67                      47%
           Plumbing works                        1.33                      29%
            Electrical works                     1.25                      21%
          False ceiling works                    0.67                      15%
           Elevators works                       0.25                      15%
     Reinforced concrete works                   1.67                      12%
        Air conditioning works                   1.00                      12%
            Wooden works                         0.33                      10%
   Fire fighting and fire protection
                 works                             0.50                     10%

*Based on frequency scale of 0,1,2,3,4 representing, never, rarely, sometimes, often, and always
respectively.



Pearson's Correlation coefficient between these two variables is 0.871 (significant at

0.01) indicating a strong positive association, which means that when the frequency of

rework increases the percentage of delay due to rework increases as well.




                                              90
The highest average percentages of delays happened to the four work categories of

aluminum and glass works, block works, plaster works, and flooring works.


For the aluminum and glass works consultant A (architectural consultant) suggested that

the rework happened to activities that took too much time in repairing and rectifying the

defective works. In the block works, the owner explained that the reworked activities

were mostly curved walls which took also too much time to be rectified. In the plaster

works, the same consultant also cited for the same reason for the big delay in rectifying

the rework.


In the flooring and wall cladding works the average percent of delay was also high

because the rectifications were repeated many times.


In the remaining work categories, the average percentage of delay were relatively low

10% to 29%, primarily because the occurrences of rework which happened to these work

categories were limited. These work categories were plumbing works, electrical works,

false ceiling works, elevators works, reinforced concrete works, air conditioning works,

and wooden works.


For the block works the percentage of delay communicated by the owner was 100%, of

consultant A (architectural consultant) was 65% and of contractor A (supervisor of

finishing and electrical contractor) was 50%.


The owner estimated high percentage of delay because he wants to get his job done as

soon as possible to start leasing his building, where the consultant is reasonable in




                                             91
estimating delay because he is trying to balance between owner and contractor, and

contractor is underestimating delay to underplay his role in the delay.


Average percent of delay in completing activities related to number of rework activities

will be automatically reduced or minimized when rework decreases.



4.3.3 Dissatisfaction of Contractors and Clients


The owner experienced his complete dissatisfaction because of the delays that happened

due to rework, such delays resulted in huge losses in his investments. The contractors

especially those who suffered a lot because of the losses due to rework stated that they

are dissatisfied.



4.3.3.1 Discussion of Dissatisfaction of Contractors and Clients


Rework require resources, such as time, material, manpower, machines which are directly

allocated to the activity to be redone, also the indirect costs like the share of the expenses

not directly allocated to the activity such as salaries of the supervisors, engineers, project

manager, etc. All such expenses will cause the contractor to be dissatisfied.


The owner estimated that he was losing almost 15,000 SR for each day delay. A project

owner is normally eager for the return on his investment, and the project delayed because

of rework or any other reason, the result is the owner dissatisfaction.


Client and contractors dissatisfaction in the case study of the rework that happened to the

project is expected.



                                             92
Comparing to the previous rework studies through the literature review, client and

contractor dissatisfaction always happens when rework increases.


Client and contractor dissatisfaction may be reduced or minimized when rework

decreases.




                                          93
     5 SUMMARY, CONCLUSION, AND RECOMMENDATIONS



This chapter includes four main sections; the first section contains the summary of this

report, the second section comprises the repot conclusion, the third section proposes the

recommendations based on the findings of this report, and the fourth and last section

recommends some suggestions for future studies.



5.1 Summary

Rework is one of the major determinants of construction productivity. This report aims at

investigating rework by determining its severity, identifying its causes, and assessing its

impact on project cost, time, and the satisfaction of the project owner and contractors.


This study is limited to a case study project of a residential commercial tower of fifteen

floors in the eastern province in Saudi Arabia. The work categories covered in this study

include those who were still working in the project during data collection phase.


The literature reviewed in this report identified two rework models, a conceptual model of

rework and a classification of rework causes model. The conceptual model of rework

portrays project characteristics, organizational management practices, and project

management practices as the factors impacting directly or indirectly rework and

consequently influencing productivity and project performance. While, the classification

model of rework causes divides rework causes into five main categories, leadership and

communication, human resource capabilities, engineering and review, construction

planning and scheduling, and material and equipment supply. Under each category there


                                             94
are four main causes which contribute to rework. Then the writer of this report proposes a

rework model based on the literature reviewed and his experience in the case study

project for the direct and indirect causes of rework.


The methodology used in this report is a case study represented by a residential /

commercial project which was chosen by the writer of this report as he was working in

that project as an architectural consultant and he noticed an appreciable amount of

rework, which was occurring in project. The procurement method which was used in the

case study consisted of separate contract for almost each work category, and the owner

representative had the role of coordinating between all of the contractors who were

working in the project. The data collection was through interviews with ten main

participants of the case study project representing the owner, consultant, and contractors.


After analyzing data, it concludes that rework influenced many work categories with

different frequencies. The severity of rework as seen by the interviewees was measured

based on a frequency scale of 0,1,2,3,4 representing never, rarely, sometimes, often, and

always respectively.


Some of the work categories had high frequencies of rework ranged between 2.00 to 3.00

such as block works, aluminum and glass works, and plaster works. Others had moderate

rework frequencies that ranged between 1.25 and 1.67 include electrical, plumbing,

flooring and wall cladding, and reinforced concrete works, which means that rework was

happening for these work categories more than rarely and less than sometimes.


Work categories with low frequencies ranged between0.25 to 1.00 include wood, fire

protection and fire fighting, false ceiling, air conditioning, and elevators works.


                                             95
Different rework causes affected the different work categories with various frequencies.

Some examples were given by the respondents illustrating the circumstances of rework

causes on different work categories. For instance, aluminum and glass works with rework

frequency of 2.33, it was explained by contractor B (supervisor of aluminum and glass

contractor) that improper subcontractor selection resulted in many defects in the works

such as wrong anchorage of aluminum supporting system to reinforced concrete slab,

plumpness of aluminum vertical supports, as well as the horizontality of aluminum

horizontal supports.


The results indicate that many rework causes affected different work categories with

various frequencies. The interview schedule contained some choices for rework causes

and proposes other for the participants to indicate if there is other rework causes. The

participants were asked to indicate the frequency of rework causes. It was revealed that

there were some rework causes affected almost all work categories with frequencies

ranged between0 to 4 include insufficient supervision, incompetent supervision and poor

workmanship. While other rework causes affected one to three work categories, also with

frequencies ranged between0 to 4 include improper subcontractor selection, improper

work protection, improper work sequencing, lack of coordination, deviations from

drawings, wrong material, defective material, and errors and omissions in drawings.


About the impact of rework on project performance, it was found that rework causes

increase in project cost ranged between 2% to 30% as well as causing percentage of delay

due to rework ranged between10% to 77% of delay. Apart from the project's cost and

time overruns, it was explained by the respondents that rework caused owner and

contractors' dissatisfaction.

                                           96
5.2 Conclusion

The used procurement method in the case study project was one of the major causes of

rework to happen. Such procurement method was the real cause behind many rework

causes such as improper work sequencing, improper work protection, and lack of

coordination.


The presence of many contractors in site without proper management for works resulted

in some works to start without considering proper work sequencing.


The non-availability of construction management company to coordinate between all of

those prime contractors gave the chance for different contractors to be careless to other

contractors works which resulted in improper work protection. Lack of coordination as a

rework cause also resulted from the presence of many contractors in site without proper

coordination among them, as the owner representative was playing such a role but he was

unable to properly manage between all of those contractors.


There are some conclusions disclosed from the study regarding severity of rework on

work categories. Block, aluminium and glass, plaster, reinforced concrete, and flooring

and wall cladding works suffered rework with frequencies of 3.00, 2.33, 2.00, 1.67 and

1.67 respectively. The contractors of these work categories were two contractors, one of

reinforced concrete, block, flooring, and plaster works and the second of aluminium and

glass works. According to the owner, the first contractor was suffering throughout the

project duration from many problems such as not providing site engineer, not providing

sufficient supervisors for works, not providing competent supervisors, and his

dependency on unskilled hired workers. As it was reported in the severity of rework

                                           97
causes, insufficient supervision, incompetent supervision, and poor workmanship

recorded the highest frequencies among other rework causes for the above mentioned

work categories.


The second contractor of the aluminium and glass works employed an incompetent

subcontractor and the contractor in his selection was considering only cost issue

regardless of subcontractors' technical competency, which resulted in wrong selection of

subcontractor and consequently caused bad work quality. Among the factors that caused

such bad quality of work were unskilled workers, incompetent supervisors, and

inadequate supervisors.


For elevators, wood, fire protection and fire fighting, false ceiling, and air conditioning

works, the severity of rework was relatively low with frequencies of 0.25, 0.33, 0.50,

0.67, and 1.00 respectively. The contractors of these works were specialty contractors;

most of them were organized, and were relatively having sufficient supervisors,

competent supervisors, and skilled workers.


Regarding rework causes, there were three rework causes that affected almost all work

categories in the case study project with different frequencies ranged from 1.00 to 4.00,

include insufficient supervision, incompetent supervision, and poor workmanship. It was

concluded that some of the contractors were concentrating in getting more projects

regardless of the availability of the required resources of skilled and experienced

manpower. Some of these contractors were getting their workers and supervisors from

hiring labour companies and such companies were rarely having the skilled or the




                                              98
experienced labour and supervisors which all caused poor workmanship, and incompetent

supervision.


Other rework causes such as wrong material, defective material, errors and omissions in

drawings, deviations from drawings, incompetent subcontractor selection, improper work

protection, improper work sequencing, and lack of coordination were happening to few

work categories ranged from one to three work categories. That was because through

certain stage of the project, quality measures were properly implemented such as field

inspections were done for different work categories for important phases of works,

materials were checked for their compliance with specifications, shop drawings were

checked, reviewed and revised (when needed) before approval by consultant, and the

presence of contractors' supervisors were checked on daily basis.


Rework has impacted project’s cost and time. The average percent increase in cost as a

result of rework for block works, flooring and wall cladding works, and plaster works,

were 30%, 22%, and 17% respectively. This is logic because they had high average

rework frequencies relative to other work categories.


The average percent increase in cost for reinforced concrete works, aluminium and glass

works, electrical works, plumbing works, wood works, false ceiling works, air

conditioning works, fire fighting and fire protection works, and elevators works was 7%,

7%, 4%, 4%, 2%, 2%, 2%, 2% and 2% respectively, this was proportioned with their

average frequencies of rework except for reinforced concrete and aluminium and glass

works that were not proportioned with the average frequencies of rework, that was




                                            99
because the respondents' estimates of percent was depending on their opinions not on

project records.


The average percent increase delay due to rework for aluminium and glass works, block

works, plaster works, and flooring and wall cladding works were 77%, 72%, 60%,

and47% respectively. And the delays for plumbing works, electrical works, false ceiling

works, elevators works, reinforced concrete works, air conditioning works, and wooden

works were 29%, 21%, 15%, 15%, 12%, 12%, 10%, and 10% respectively, that was

proportioned with their average frequencies of rework, except for some work categories

which had percent of delay was not proportioned with its average frequency of rework

such as elevators, air conditioning, and reinforced concrete works, that was because of the

respondents estimates were according to opinions not from project records.


Rework caused dissatisfaction to the project contractors and owner, the contractor

dissatisfaction from rework was because of the expenses that the contractor pays in the

extra resources of the materials equipment and manpower that resulted from rework.


The owner's dissatisfaction stemmed from the delays and associate loss of project

revenues.



5.3 Recommendations

To reduce rework in the case study project and similar construction projects the following

precautious are recommended




                                           100
        When using multiple contractors as a procurement method, it is recommended to

         use a construction management company to manage the process.

        Project consultants (A/E) must review and revise (if needed) the contractor's

         shop drawings properly to avoid errors and omissions in drawings.

        Project consultants (A/E) must review and revise (if needed) the contractor’s

         submittals such as material submittals, quality control and quality assurance

         plans, submittals schedule, etc.

        When practical, the contractor should make a mock up sample for major and

         repeated project elements; it should be inspected by the field inspector and

         approved by the owner representative before proceeding with works.

        Owner's and contractor's inspectors should inspect each work phase before

         proceeding to the subsequent phase.

        The project owner, consultant, contractors, and subcontractors should ascertain

         that project personnel possess the required skills and experience. Training

         programs should be used when appropriate.

        The owner should require from his project contractors the organization chart and

         qualification of key project personnel before the commencement of the works to

         ascertain their adequacy.

        Representatives of the project should check regularly the presence of all the

         contractor's and the subcontractors' staff on site.


To reduce rework caused by subcontractor selection, contractor should consider the

following in the selection of his subcontractors:




                                             101
       Subcontractor's performance in recently completed projects.

       Subcontractor’s staff qualifications, experience and skills.


The usage of wrong material in construction projects can be avoided by checking the site

delivered material more than once, and by different entities, such as inspecting the

material by the contractor’s supervisor, and by the store keeper, then by the field

inspector before installation.


Defective material as a rework cause may be reduced in construction projects by

implementing quality control measures such as inspecting materials when delivered to site

by different entities such as contractor’s supervisor, store keeper, and field supervisor.


The improper work sequencing as a rework cause can be reduced by frequent checking

and updating of the project time schedule.


To reduce errors and omissions from happening in contract drawings in construction

projects the following recommendations should be followed:


       Each design phase should be checked by the client’s representative and approved

        before proceeding to the next phase.

       Contract drawings should be checked and approved by contractor before

        commencing shop drawings production.

       Shop drawings should be checked by site consultant engineers for approval before

        starting construction.


To reduce deviations from drawings it is recommended to inspect works and check its

compliance with drawings frequently by contractor's supervisor and field inspector.


                                             102
5.4 Recommendations for Future Studies

It is recommended to do further studies on rework in the following areas:


   1. Direct and indirect costs of rework in construction projects.

   2. Rework-caused delays in construction projects.

   3. Impact of rework on contractors.

   4. Impact of rework on owners.




                                           103
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                                          108
 Appendix

Interview Schedule




        ‌
        ‫أ‬
 Interviewee
      title:
     Date of
   Interview:
1. For the following work categories, how frequent were rework occurrences?
2. For each work category indicate the cause of rework and its frequency.
3.What percent increase in the cost for each work category as a result of rework?
4. What percentage delay in completing the activities in each category due to rework in general?
5. Indicate any impact of rework on project performance or productivity other than cost and time.

work categories are: Reinforced concrete works, Block works, Waterproofing and thermal insulation works, Plaster works, Screed works, Flooring and wall cladding works
works, False ceiling works, Paining works, Aluminum and glass works, Wooden works, Electrical works, Air conditioning works, Fire fighting and fire protection works, and
Plumbing works, Elevators works.

                  Frequency
                                                          Never                                     Rarely          Sometimes               Often               Always
                    scale
                                                           0                                          1                  2                    3                    4
                      F1                   = Frequency of rework for category
                      F2                      = Frequency of rework cause

                                                                                                                                                                                                        Rework Cause

                                                                                                                                                                                                                                                Errors &                                          Insrease percent      Percentage of     Other impact on
                                                                                            F1 = Frequency of        Poor               Insufficient         Incompetent                                                           Defective
Category no.                                 Work Category                                                                                                                  Wrong material   Wrong equipment Defective material                omissions in   Client's change   Other (specify)   of cost as a result    dealy due to   project performance
                                                                                             rework category      workmanship           Supervision           supervision                                                         equipment
                                                                                                                                                                                                                                                drawings                                              of rework            rework         or productivity

                                                                                                                                                                                                F2 = Frequency of rework cause


      1         Reinforced concrete works


      2         Block works


      3         Waterproofing and thermal insulation works


      4         Plaster works


      5         Screed works


      6         Flooring and wall cladding works


      7         False ceiling works


      8         Painting works


      9         Aluminum and glass works


      10        Wooden works


      11        Electrical works


      12        Air conditioning works


      13        Fire protection and fire fighting works


      14        Plumbing works


      15        Elevator works

				
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