Cunningham Lindsey United Kingdom
Subsidence Scanning Centre, Woodhead House, Centre 27 Business Park, Woodhead Rd, Birstall, WF17 9TD
Telephone 01622 608810 Facsimile 01622 608801
Policyholder:
Subject Property Address:
35a, Sydenham Park
London
SE26 4EE
INSURANCE CLAIM
CONCERNING SUSPECTED SUBSIDENCE
ENGINEERING APPRAISAL REPORT
This report is prepared on behalf of Prudential Assurance for the purpose of investigating a
claim for subsidence. It is not intended to cover any other aspect of structural inadequacy or
building defect that may otherwise have been in existence at the time of inspection.
Date: 9/11/2009
Cunningham Lindsey Ref: MNHPD/TH/3381571
Continuation / 2 Our Ref: MNHPD/TH/3381571
INTRODUCTION
The technical aspects of this claim are being overseen by our Project Manager Mathew
Hastie BSc (Hons), in accordance with our Project Managed Service.
DESCRIPTION OF BUILDING
The subject property is a mid terrace property built circa 1900 of traditional construction.
CIRCUMSTANCES OF DISCOVERY OF DAMAGE
The risk address was subject to a subsidence claim in 2004 where upon investigations
concluded that the damage was indicative of root exacerbated clay shrinkage subsidence to
the front right hand corner. Following the removal of vegetation close to the area of damage
a period of monitoring was undertaken which revealed the building to be stable.
Superstructure repairs were subsequently completed in early 2007. The insured noted minor
cracking shortly after completion of the repairs, which was initially deemed to be shrinkage /
thermal movement however the crack damage has progressed with more pronounced
movement noted during the summer of 2009. The claim was subsequently reinitiated to
insurers under the subsidence section of the policy.
NATURE AND EXTENT OF DAMAGE
Description and Mechanism
The principal damage takes the form of tapering cracking within the facing brickwork on the
front and rear elevations up to 3mm wide. Internal cracking was recorded within the
plastered finish. Horizontal separation was recorded at the party wall ceiling junction to the
right hand elevation.
The indicated mechanism of movement could be indicative of a downward movement of the
end of terrace property number 35 resulting in a ‘pull effect’ on the risk address.
Significance
The level of damage is slight, and is classified as category 2 in accordance with BRE Digest
251 - Assessment of damage in low-rise buildings.
Onset and Progression
We consider that the damage has occurred recently.
It is likely that movement will be of a cyclical nature with cracks opening in the summer and
closing in the winter.
Continuation / 3 Our Ref: MNHPD/TH/3381571
SITE INVESTIGATIONS
A site investigation was previously commissioned in 2004 and was carried out by CET
Group Ltd under our supervision.
A trial pit borehole was excavated adjacent to the front right-hand corner of the property to
determine foundation depth and subsoil conditions. The foundations were found to comprise
of a concrete brick/clinker foundation founded at a depth of 800mm below ground level
bedded on a silty clay.
The extended borehole revealed this clay continues to a depth of at least 3.2 metres at which
point, site investigations were terminated.
MONITORING
We believe that it is likely that there will be a short term change in crack widths following
the completion of mitigation measures, before the damage is seen to stabilise. We do
however believe that the damage will be seen to stabilise. We therefore propose to continue
to monitor the crack widths to confirm when stability has occurred. We would then propose
to agree the detailed scope of repair works at the end of the monitoring period.
CAUSE OF DAMAGE
We know from the previous site investigation that the foundations of the property in the area
of damage have been built at a relatively shallow depth, bearing onto shrinkable clay subsoil.
The soil is susceptible to movement as a result of changes in volume of the clay with
variations in moisture content. The orientation of the cracking within the property is
indicative of possible downward movement of the neighbouring property which has resulted
in ‘pulling affect’ on the mid terrace house. A number of large deciduous trees are within
the boundary of an adjacent property. In this case, the damage therefore appears to have
been caused by clay shrinkage subsidence following moisture extraction by nearby
vegetation.
RECOMMENDATIONS
A program of crack width monitoring has been established to ascertain the movement
pattern. We have also requested permission to undertake a program of level monitoring at
the neighbouring property in-conjunction with the risk address to ascertain if the
neighbouring property is subsiding and causing the subsequent damage.
Repair
We have not yet decided on the final type of repair required, but have produced an outline of
the most likely requirements. This involves undertaking superstructure repairs and
redecoration. This decision has been taken based on our knowledge and experience of
dealing with similar claims. In addition the results of the Site Investigation, laboratory
testing and monitoring will be taken into account.
Cunningham Lindsey United Kingdom
Subsidence Scanning Centre, Woodhead House, Centre 27 Business Park, Woodhead Rd, Birstall, WF17 9TD
Telephone 01622 608810 Facsimile 01622 608801
Mathew Hastie
Project Managed Services
E-mail: PMSmaidstone@cl-uk.com
LEVEL MONITORING - RELATIVE SURVEY READINGS
Provider Details Client Details Risk Address
Insurance Co.: Prudential Occupier: Mr Leung
Name: CETSafehouse
Client Name: Cunningham Lindsey Address: 35&35a Sydenham Park
Our Ref: 00/24080 Technical Mgr: Mr M Hastie Address:
Date of Issue: 15/1/11 Email: pmsmaidstone@cl-uk.com Town: London
Client Ref: 3381571 County:
Monitoring Details Address: 3-4 North Court Post Code: SE26 4EE
Instruction Date: 15/12/09 Address: Armstrong Road Tel Day: 0208 693 8288
First Reading Date: 26/01/10 Town: Maidstone Tel Eve: 07957 828828
Maximum No Visits: TBC County: Kent Mobile:
Anticipated Expiry Date: TBC Post Code: ME15 7AF Other:
Monitoring Int (Wks): 6 Other Email: Mark.Hastie@cl-uk.com Other:
Target Date: 9/3/10 7/4/10
Reading Date: 26/1/10 26/1/10 7/4/10 18/5/10 30/6/10 10/8/10 25/9/10 2/12/10 12/1/11
Issue Date: 7/2/10 3/3/10 11/4/10 25/5/10 14/7/10 18/8/10 30/9/10 7/12/10 15/1/11
Row Point X Co- Y Co-
ordinate ordinate
1 2 3 4 5 6 7 8 9 10 11 12
No. Name
1 4 0.00 0.00 10.3710 10.3701 10.3706 10.3686 10.3693 10.3683 10.3692 10.3691 10.3698
2 0.00 -0.10
3 0.60 -0.10
4 3 0.60 -0.30 10.4487 10.4476 10.4475 10.4471 10.4469 10.4480 10.4485 10.4484 10.4474
5 2 2.00 -0.30 10.4487 10.4472 10.4473 10.4478 10.4472 10.4484 10.4483 10.4481 10.4481
6 2.00 -0.10 10.4458 10.4444 10.4446 10.4453 10.4444 10.4454 10.4451 10.4452 10.4451 #DIV/0! #DIV/0! #DIV/0!
7 1 3.00 -0.10 10.4429 10.4415 10.4418 10.4427 10.4416 10.4423 10.4418 10.4423 10.4421
8 3.40 -0.10
9 3.40 9.00
10 12 -0.60 9.00 10.5822 10.5822 10.5832 10.5841 10.5838 10.5720 10.5701 10.5730 10.5783
11 11 -3.00 9.00 10.5653 10.5653 10.5667 10.5671 10.5633 10.5460 10.5433 10.5475 10.5570
12 10 -6.00 9.00 10.5565 10.5565 10.5589 10.5586 10.5502 10.5288 10.5257 10.5332 10.5447
13 9 -6.00 6.50 10.5273 10.5273 10.5293 10.5280 10.5224 10.5019 10.4999 10.5075 10.5174
14 8 -6.00 4.00 10.4373 10.4373 10.4384 10.4365 10.4340 10.4176 10.4160 10.4227 10.4296
15 7 -6.00 -0.10 10.4160 10.4160 10.4163 10.4132 10.4114 10.4057 10.4054 10.4094 10.4119
16 6 -4.00 -0.10 10.5194 10.5194 10.5194 10.5166 10.5155 10.5121 10.5122 10.5148 10.5166
17 -4.00 -0.30
18 5 -0.50 -0.30 10.3715 10.3715 10.3716 10.3692 10.3700 10.3696 10.3692 10.3701 10.3702
19 -0.50 0.10
20 0.00 0.10
21
22
23
24
25
Sketch Plan Comments
11 12
10 Not same brick course
No access to to install stations at rear of
property
Stations 5 - 12 added 24/2/2010
9
8
7
4
1
6 5
3 2
Deep Datum
File 24080 Levels.XLS Readings Printed on 15/01/2011
RING - DISTORTION SURVEY CHART LEVEL MONITORING - RELATIVE MOVEMENT SKETCH
Client: Cunningham Lindsey Client Ref: 3381571 CETSafehouse Ref: 00/24080
10; -12
9; -10
11; -8
8; -8
12; -4
7; -4
6; -3
5; -1
4; -1
3; -1
2; -1
1; -1
Datum Reading Reading 1 (26/1/10) Reading 2 (26/1/10) Reading 3 (7/4/10) Reading 4 (18/5/10)
Reading 5 (30/6/10) Reading 6 (10/8/10) Reading 7 (25/9/10) Reading 8 (2/12/10) Reading 9 (12/1/11)
Reading 10 (0/1/00) Reading 11 (0/1/00) Reading 12 (0/1/00)
Notes:
Vertical distorted scale 1: 20
Chart is displaying Subsidence
Point labels give level difference of last reading from original datum in mm.
File 24080 Levels.XLS Sketch Printed on 15/01/2011
LEVEL MONITORING - RELATIVE SURVEY READINGS
Client: Cunningham Lindsey Client Ref: 3381571 CETSafehouse Ref: 00/24080 Chart Scale 1:1000
1 1
10.0
8.0
6.0 Date
Difference in reading
4.0
Point 1
2.0
Point 2
mm
0.0 0.00 0.00 0.10
-0.40 -0.20 -0.30 -0.20
-0.40 -0.30
-0.60
-0.70 -0.60 -0.60
-0.80
-0.90
-1.10 -1.10
-1.20 -0.90 -1.10 -1.20 Point 3
-1.40
-1.50 -1.40 -1.60 -1.30
-1.50 -1.40 -1.30
-1.70
-1.80 -1.90 -1.80 -1.90
-2.0 -2.30
-2.40 -2.30
-2.70
Point 4
-4.0
10
10
10
10
10
10
10
10
11
/20
/20
/20
/20
/20
/20
/20
/20
/20
-6.0 Point 5
/0 1
/0 1
/0 4
/0 5
/0 6
/0 8
/0 9
/1 2
/0 1
26
26
07
18
30
10
25
02
12
-8.0
-10.0
2 1
35.0
25.0
Date
Difference in reading
15.0
Point 6
5.0 Point 7
mm
2.40
2.00 2.10
1.10
0.30 0.70
0.00 0.00 0.00 -0.80
-2.80 -2.80
-5.0
-3.30
-3.90
-4.60
-4.90 -4.60 -4.10 Point 8
-6.30 -7.30 -7.20 -6.60
-7.70
-10.30 -10.60 -9.90
-11.80 Point 9
-15.0 -14.60
-19.70
-21.30
-19.80 Point 10
-23.30
-25.0 -25.40
-27.70 -27.40
-30.80
10
10
10
10
10
10
10
10
11
-35.0
/20
/20
/20
/20
/20
/20
/20
/20
/20
/0 1
/0 1
/0 4
/0 5
/0 6
/0 8
/0 9
/1 2
/0 1
26
26
07
18
30
10
25
02
12
3 6
25.0
20.0
15.0
Difference in reading
Date
10.0
5.0
mm
1.40 1.90
1.80 1.60
1.00
0.0 0.00 0.00 Point 11
-2.00
-3.90
-5.0
-8.30
-9.20
-10.0 -10.20
-12.10 Point 12
-15.0
-17.80
-19.30
-20.0
-22.00
-25.0
10
10
10
10
10
10
10
10
11
/20
/20
/20
/20
/20
/20
/20
/20
/20
/0 1
/0 1
/0 4
/0 5
/0 6
/0 8
/0 9
/1 2
/0 1
26
26
07
18
30
10
25
02
12
24080 Levels Charts Printed 15/01/2011