43_Bottlelake_Drive_Structural_Report

Document Sample
43_Bottlelake_Drive_Structural_Report Powered By Docstoc
					Property Inspection


    43 Bottle Lake Drive
               Parklands
  STRUCTURAL REPORT




                 June 2012
                                                                               43 Bottle Lake Drive – Parklands




This document has been prepared for the benefit of Steve Rooke as at 5.6.2012. No liability is accepted by this
company or any employee or sub-consultant of this company with respect to its use by any other person.




                             Quality Assurance Statement and Revision History

Revision    Date        Prepared By                        Reviewed By                        Status
1           11.6.2012   Ben Hayward                        Timmothy Day                       Approved
                        Civil Engineer                     Structural Engineer
                        BE Hons (Civil)                    BE Hons (Civil)
                        CPEng – Mem No: 247489             CPEng – Mem No: 1005159




Viden Consulting Engineers Ltd

PO Box 16571
Hornby, 8442
Christchurch
New Zealand

Tel: 64-21-0294 6595
Web: www.viden.co.nz
                                                                                                                         43 Bottle Lake Drive – Parklands




Contents


Executive Summary .............................................................................................................................................. 1

1.       Introduction ............................................................................................................................................... 1

2.       Inspection ................................................................................................................................................... 2
         2.1           Structural Form ........................................................................................................................... 2
         2.2           General........................................................................................................................................ 3
         2.3           Detailed Findings ........................................................................................................................ 3

3.       Summary .................................................................................................................................................... 5

Appendix A – Site Location and Level Survey ....................................................................................................... 6

Appendix B – Site Photos...................................................................................................................................... 8
                                                                               43 Bottle Lake Drive – Parklands




Executive Summary
Viden group engineers have been engaged to conduct a pre-sale structural inspection of 43 Bottle Lake
Drive, Parklands, Christchurch. The purpose of the inspection and this report are to ascertain and document
the extent of any structural damage caused through the recent seismic events in Canterbury, covering the
period September 2010 to June 2012.

A detailed visual inspection of the main structural elements of the house has been conducted, with a review
of the structural condition and integrity as may be typical for a house of this age, material and construction.
No review of the original design documentation, compliance with building code clauses B1/B2, or building
consent has been undertaken as part of the inspection and this subsequent report. In addition, it should be
noted that assessment of the baseline capacity of the structure is beyond the scope of this report. Further to
this, Viden has not made any assessment of the structural stability or building safety in connection with
future aftershocks or earthquakes – which have the potential to damage the building. This report is limited
by the restricted ability to carry out inspections due to coverings of many elements and no destructive
testing has been undertaken. The report does not address defects that are not reasonably discoverable on
visual inspection, including defects in inaccessible places.

Visual inspection of the property at 43 Bottle Lake Drive has not revealed any signs of concerning
structural damage. The house is in acceptable structural condition and all damage detailed below is of an
aesthetic nature and can be remediated in due course.

The original inspection and this subsequent report are carried out in accordance with the ACENZ Short Form
Model Conditions for Engagement of Consulting Engineers, copies available at the following web address.
(http://www.acenz.org.nz/UploadedDocs/Contracts/ACENZ_ShortFormAgrmt_July2011.docx)



1.     Introduction
Viden Group conducted a pre-sale structural inspection of the 43 Bottle Lake Drive property for the current
owner on the 2nd of June 2012. The inspection was conducted by a New Zealand Professional Engineer.

The land was visually inspected and compared along with the Tonkin and Taylor detailed land reports and
zoning maps for Christchurch. This has identified the house lying within the Green Zone Technical Category 3
which is described as being “generally suitable to be repaired and rebuilt on” but with “moderate to
significant land damage possible from future significant earthquakes” (CERA and Department of Building and
Housing Information Sheet October 2011 www.landcheck.org.nz/Content/PDFs/green-zone-factsheet.pdf). For
houses in this technical category that have suffered foundation damage, site-specific geotechnical
investigation and specific engineering design may be necessary for repair or rebuilding of those elements.




Status – Approved                                                                                               June 2012
Project Number – CH0250                                                              Ref 43 Bottle Lake Drive – Parklands
                                                                                43 Bottle Lake Drive – Parklands




2.       Inspection


2.1      Structural Form

43 Bottle Lake Drive is characterised as a lightweight timber residence with brick cladding typical of modern
houses in New Zealand. The house has timber structural elements.

The house is a single story residence. The gravity system consists of a profiled metal roof supported on
timber purlins and timber trusses, spanning between external and internal load-bearing walls. The ceiling is
lined with plasterboard supported from steel joists spanning between external and internal load-bearing
walls. The walls are timber framed, with internal plasterboard cladding and external brick cladding. The
walls transmit loads vertically to the slab-on-grade concrete slab.

Residential construction of this type is typically detailed to use the ceiling lining as a horizontal diaphragm,
transferring lateral loads to the vertical resisting elements (walls) which transmit the load into the
foundation. The lateral load transfer capacity of any internal bracing walls is provided through ‘panel’ action
of the plasterboard linings and their fixture to the timber framing studs behind, which ultimately act as
vertical compression and tension chords attached to the timber subfloor framing and foundation. The
external walls will provide significant bracing capacity, acting as shear walls to transmit loads into the
foundation.

Founded on a concrete slab-on-grade, the house structure relies on adequate vertical bearing capacity and
lateral resistance of the soil on which the pad is constructed. The ability of the concrete slab foundation to
transmit lateral loads into the ground is typically a function of the vertical area of the sides of the slab or
thickenings and the embedment into the soil, and friction interaction between the underside of these
elements and the soil beneath.

A connected internal access double garage is located on the property, with vertical structure comprising
profiled metal roofing spanning over timber framing which spans between an external timber wall and the
timber framing of the house. The floor is a concrete slab-on-grade.

The house is defined as a Type C structure in the DBH’s Guide: Revised guidance on repairing and rebuilding
houses affected by the Canterbury earthquake sequence (Nov 2011) and Appendix C (April 2012). Hereafter
referred to as the DBH Guide.




Status – Approved                                                                                                June 2012
Project Number – CH0250                                                               Ref 43 Bottle Lake Drive – Parklands
                                                                              43 Bottle Lake Drive – Parklands




2.2      General

The house is a single storey structure.

The house has timber roof framing and trusses and internal plasterboard clad timber walls. The house is
founded on a concrete slab-on-grade.

The house has brick cladding and a profiled metal roof. All internal joinery is timber and all window frames
are aluminium.

The connected internal access garage is timber framing with internal plasterboard cladding and external
brick veneer. The garage is founded on a concrete slab-on-grade.

For the purpose of this report, the elevation facing Bottle Lake Drive is North. You enter the house from the
East elevation (refer to Figure 1).



2.3      Detailed Findings

The property showed no signs of liquefaction at the time of inspection and it was reported by the owner that
no liquefaction occurred during the recent seismic events, although the general area and roadways showed
signs of moderate-to-significant liquefaction. There were also no signs of land damage such as lateral spread
or fissures. The concrete paths around the house were generally in good condition with no obvious
differential settlement noted. There was some minor movement noted between the slab-on-grade
foundation and the concrete paths (Figure 4). This movement was in the order of 5mm. Further to this, there
is some minor movement noted in the external paving stones. The movement in the pathways does not
reduce the structural integrity of the house, however, it is an indication that movement has occurred.
Further to this, there was one 1.5mm wide crack in the external concrete path on the south eastern side of
the house (Figure 5, Figure 6). This crack does not reduce the structural integrity of the house and can be
remediated in due course.

The perimeter of the concrete slab foundation was inspected at various locations around the house and was
in good condition. There were no signs of cracking.

The concrete slab foundation was inspected in the garage and no cracks were identified. There was one
crack that had formed at the entrance way along the moulded drop down entrance, however this did not
reflect into the main foundation slab (Figure 9, Figure 10). This crack does not significantly reduce the
structural capacity of the foundation and can be remediated in due course. The slab was level with no signs
of differential movement. The shrinkage control joints were inspected but it was not possible to determine if
the slab was reinforced (Figure 11). However, due to the excellent condition of the concrete slab with no
signs of thermal cracking, it is assumed that some degree of mesh reinforcing is present.

It was not possible to visually inspect the concrete slab foundation inside the house due to carpet linings,
however on internal inspection there were no major cracks noted by testing the integrity underneath the

Status – Approved                                                                                              June 2012
Project Number – CH0250                                                             Ref 43 Bottle Lake Drive – Parklands
                                                                               43 Bottle Lake Drive – Parklands




carpet (touch test only). Further to this, all areas of the house that are tiled showed no evidence of tile
movement or popping which further indicated the good condition of the foundation. Levels were taken
through the house with a digital spirit level to check for localised settlement. All levels were less than 0.5%
(Figure 12, Figure 13, Figure 14) which is the performance criteria for not requiring structural repairs (DBH
Guide Table 2.2). Further to this a levelling exercise was undertaken with a gas level. This survey showed that
the house has a maximum vertical differential level of 20mm (Figure 2). The overall difference in levels
running east-west is 15mm and north-south is 10mm. These measured levels are within acceptable
tolerances and less than the 50mm maximum differential settlement performance criteria recommended by
the DBH Guide for structural repairs or revelling. In summary, the slab-on-grade foundation is in acceptable
condition.

There is a small amount of movement and grout cracking at the interface of the tiles and the left hand wall
at the entrance way (Figure 15, Figure 16, Figure 17). The carpet was lifted near this location which revealed
a clean 5mm wide separation. Comparing this separation with the shrinkage control joints in the garage, it is
assumed that this gap is a shrinkage control joint cut at the interface of the hallway and the entrance way
running east-west. However, without lifting the carpets further the length of this joint could not be
determined. It was not possible to see through the joint to determine whether any cracking had occurred in
the lower section of the slab below the joint. However, if cracking has occurred the width of the crack would
be less than 2-3mm based on the visual assessment. The DBH Guide recommends that structural repair is not
required for cracks less than 5mm in width (Table 2.2). The cracking and movement in grout around the tiles
is likely to be related to minor movement around this construction joint. No further cracking was indentified
in the slab around this area (touch test only due to carpet coverings). Based on the visual inspection the
movement noted around this area does not significantly reduce the structural capacity of the house.

All other tiled areas of the house showed no evidence of movement of cracking.

The external brick cladding is in very good condition and only one minor stepped crack was located. This
crack is minor and does not significantly reduce the structural capacity of the house (Figure 7). The crack can
be remediated in due course. All walls are straight and plumb within construction tolerance (Figure 8). The
interface between the brick cladding and the eve soffit was in good condition with no signs of permanent
deformation in these areas.

The internal plasterboard lining is generally in good condition. There are a number of minor cracks (between
0.2-0.5mm) that are visible at various locations in the house, typically above the window frames (Figure 18).
These cracks are typical of most houses in Christchurch following the seismic activity and do not compromise
the structural integrity of the house. These cracks can be remediated in due course for aesthetic purposes.
All walls are straight and plumb (Figure 20).

The internal ceiling lining is also in good condition. One crack was indentified which appears to run along a
join line (Figure 19). This crack is only 0.5mm in width and does not significantly reduce the structural
capacity of the house. The crack can be repaired in due course.

The timber roof framing and steel joists in very good condition with no evidence of movement or member
failure in the earthquake (Figure 21, Figure 22, Figure 23). All nails plates on the timber trusses and
connections inspected were in good condition and there was no evidence of movement noted.


Status – Approved                                                                                               June 2012
Project Number – CH0250                                                              Ref 43 Bottle Lake Drive – Parklands
                                                                                43 Bottle Lake Drive – Parklands




3.     Summary

The 43 Bottle Lake Drive property is in acceptable structural condition. No visually inspected elements of the
house inspected show any significant structural damage attributable to the recent Canterbury Earthquakes
and the structural integrity of the house has not been compromised. All minor defects mentioned above can
be remediated in due course if required.

Please don’t hesitate to contact the undersigned to clarify anything contained in this report.

Yours Sincerely
Inspected By:




Ben Hayward
Director – Civil Engineer
CPEng, MIPENZ (247489)




Status – Approved                                                                                                June 2012
Project Number – CH0250                                                               Ref 43 Bottle Lake Drive – Parklands
                                                                                     43 Bottle Lake Drive – Parklands




Appendix A – Site Location and Level Survey

                                                                            NORTH




                 Figure 1 – 43 Bottle Lake Drive, Waimairi Beach, Christchurch (reference North shown)




Status – Approved                                                                                                     June 2012
Project Number – CH0250                                                                    Ref 43 Bottle Lake Drive – Parklands
                                                                                    43 Bottle Lake Drive – Parklands




           Figure 2 – Level survey. Sketch not to scale. All measurements shown in mm. 0 is base reference.




Status – Approved                                                                                                    June 2012
Project Number – CH0250                                                                   Ref 43 Bottle Lake Drive – Parklands
                                                                                      43 Bottle Lake Drive – Parklands




Appendix B – Site Photos




                                  Figure 3 View of 43 Bottle Lake Drive East Elevation.




                          Figure 4 Minimal movement between concrete paths and foundation.




Status – Approved                                                                                                      June 2012
Project Number – CH0250                                                                     Ref 43 Bottle Lake Drive – Parklands
                                                                                  43 Bottle Lake Drive – Parklands




                                    Figure 5 1.5mm wide crack in concrete path.




               Figure 6 1.5mm crack in concrete path. Minimal movement between path and foundation.




Status – Approved                                                                                                  June 2012
Project Number – CH0250                                                                 Ref 43 Bottle Lake Drive – Parklands
                                                                                   43 Bottle Lake Drive – Parklands




                          Figure 7 Stepped crack in cladding. Terminates after 3 bricks.




                                   Figure 8 External walls straight and plumb.


Status – Approved                                                                                                     June 2012
Project Number – CH0250                                                                    Ref 43 Bottle Lake Drive – Parklands
                                                                                       43 Bottle Lake Drive – Parklands




                                  Figure 9 Minor crack in garage entrance drop down.




               Figure 10 Minor crack in garage entrance drop down terminates at interface of garage slab.



Status – Approved                                                                                                       June 2012
Project Number – CH0250                                                                      Ref 43 Bottle Lake Drive – Parklands
                                                                                      43 Bottle Lake Drive – Parklands




                          Figure 11 No cracking garage slab. Shrinkage control joints visible.




                                            Figure 12 Kitchen floors level.




Status – Approved                                                                                                       June 2012
Project Number – CH0250                                                                      Ref 43 Bottle Lake Drive – Parklands
                                                                43 Bottle Lake Drive – Parklands




                          Figure 13 Living room floors level.




                          Figure 14 Entranceway floors level.




Status – Approved                                                                                June 2012
Project Number – CH0250                                               Ref 43 Bottle Lake Drive – Parklands
                                                                                      43 Bottle Lake Drive – Parklands




                   Figure 15 Shrinkage control joint visible under carpet with some tile grout damage.




                            Figure 16 Tile movement and grout damage near entranceway.




Status – Approved                                                                                                      June 2012
Project Number – CH0250                                                                     Ref 43 Bottle Lake Drive – Parklands
                                                                                43 Bottle Lake Drive – Parklands




                          Figure 17 Continuation of assumed shrinkage control joint.




                          Figure 18 Typical minor cracking (0.5mm) in plasterboard.




Status – Approved                                                                                                 June 2012
Project Number – CH0250                                                                Ref 43 Bottle Lake Drive – Parklands
                                                                                 43 Bottle Lake Drive – Parklands




                          Figure 19 Typical minor cracking in ceiling plasterboard.




Status – Approved                                                                                                 June 2012
Project Number – CH0250                                                                Ref 43 Bottle Lake Drive – Parklands
                                                                                         43 Bottle Lake Drive – Parklands




                          Figure 20 Internal walls straight and plumb within construction tolerance.




Status – Approved                                                                                                         June 2012
Project Number – CH0250                                                                        Ref 43 Bottle Lake Drive – Parklands
                                                                                     43 Bottle Lake Drive – Parklands




                          Figure 21 Ceiling timber framing and connections in good condition.




                          Figure 22 Timber beam in good condition and all connections sound.




Status – Approved                                                                                                     June 2012
Project Number – CH0250                                                                    Ref 43 Bottle Lake Drive – Parklands
                                                                               43 Bottle Lake Drive – Parklands




                          Figure 23 Timber members and connections in good condition.




Status – Approved                                                                                                  June 2012
Project Number – CH0250                                                                 Ref 43 Bottle Lake Drive – Parklands

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:12/28/2013
language:Unknown
pages:22