A case study identifying the advantages and disadvantages of certain foundation types
J. & W. LOWRY LIMITED
This report has been
prepared for J & W Lowry
Limited
Produced By Thomas Elliott Foster
A case study identifying the advantages and disadvantages of certain foundation types
ID:07004101
12/3/2012
Table of Contents
1.0.
Brief ..................................................................................................................................... 2
2.0.
Introduction .......................................................................................................................... 3
2.1.
Foundation types Covered in this Report............................................................................. 3
2.2.
Considered factors affecting the foundations ...................................................................... 3
2.3.
Foundation ........................................................................................................................... 3
2.4.
Elements requiring foundations ........................................................................................... 4
2.5.
Information required before designing foundations ............................................................ 4
3.0.
Assumptions/Belief of ground type/condition ..................................................................... 5
3.2. After the nature of the ground has been ascertained a risk register should be completed to
identify; ........................................................................................................................................... 5
3.3.
A remedial strategy should then be formed subject to;........................................................ 6
4.0.
Report 1 – Shallow foundation ............................................................................................ 7
4.1. Strip Foundation (see appendix 1 for detail) (trench foundations are very similar to strip
foundations, differing mainly in thickness of foundation).............................................................. 7
4.2.
Pad foundations .................................................................................................................. 10
4.3.
Raft foundations ................................................................................................................. 13
5.1.
Friction/Driven piles/Displacement piles .......................................................................... 15
5.2.
End-bearing piles/Bored piles/Replacement piles ............................................................. 18
6.0. Decision matrix (showing the value you each foundation through a rating system of 1-5 in
which 1 – poor and 5 – ideal)........................................................................................................ 20
7.0
Conclusion ......................................................................................................................... 21
Reference ...................................................................................................................................... 22
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1.0.
Brief
A client has identified a city centre, brownfield site (with possible obstructions within the
ground) that is surrounded by buildings and has bedrock 8m below ground level. The site is to
accommodate a five storey office building that is to house 250 staff.
The client requires a technical report that will enable them to understand the suitability of
various substructures. Where appropriate the report shall identify relevant guidance,
legislation and sustainability considerations relating to the proposed building.
The report must:
1) Illustrate various foundation types (excluding piles) that may be used to support a building.
Investigate and analyse the advantages and disadvantages of these various systems including
the way in which they transmit the loads to the ground. Suggest when it may be appropriate
to use each of the foundation types.
2) Illustrate various types of pile foundation that may be used to support a building.
Investigate and analyse the advantages and disadvantages of these various systems including
the way in which they transmit the loads to the ground. Suggest when it may be appropriate
to use each of the pile types.
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2.0.
Introduction
Foundations are primarily required to support building construction but on brownfield sites
they can also act as a barrier to contaminants. The performance of foundation materials can be
adversely affected by contaminants
Charles, J (2004).
2.1.
Foundation types Covered in this Report
a. Shallow foundations
i. Strip foundations
ii. Pad foundations
iii. Raft foundation
b. Deep foundations
i. Pile foundations
1. Friction/Driven piles/Displacement piles
2. End-bearing piles/Bored piles/Replacement piles
2.2.
Considered factors affecting the foundations
a. Live Loads
b. Dead Load (5 storey building)
c. Wind Load
d. Earthquake
e. Uplift
f. Structural Member Forces
g. Horizontal Pressures below Grade
i. Sum of the loads is considered the combined load
2.3.
Foundation
a. Must transfer the combined load to the required load bearing stratum, while coping
with
i. The grounds settlement characteristics
ii. Possible ground heave
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iii. The impact of creep on the foundation
b. Should be technically and economically feasible
2.4.
Elements requiring foundations
a. External walls
b. Separating walls
c. Chimney breasts
d. Piers
e. Internal loadbearing or masonry walls
f. Sleeper walls
2.5.
Information required before designing foundations
a. site and ground appraisals
b. dwelling design
c. site layout
d. site levels
e. sulphate and acids in ground or groundwater
f. trees
g. frost susceptible soils
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3.0.
Assumptions/Belief of ground type/condition
3.1.
A Brownfield site can have many hazards, these need to be identified so remedies can
be taken to eliminate/limit their impact on the building and its’ users. Most sites have a
Land Condition Record (LCR) which should provide a record of the nature of any
contamination and the previous used of the land. Along with the LCR it is recommended to
consult a specialist in land contamination (SILC). The chart below illustrates the
recommended steps to take from initial assessment to complete construction.
Charles, J (2004).
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3.2.
After the nature of the ground has been ascertained a risk register should be completed
to identify;
a. Hazards
b. The nature and degree of risk resulting from the hazards
c. A planned response
d. An estimated effect of response
e. The nature and degree of residual risk and with whom it lies
3.3.
A remedial strategy should then be formed subject to;
a. Technical adequacy
b. Cost
c. Environmental effects
d. Perception
NHBC (2011)
Note: Advice and guidance on foundations have been given solely based on the clients’
information given in the brief (1.0). Should any information change the advised foundation type
should be re-analysed as it may not be suitable.
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4.0.
Report 1 – Shallow foundation
Illustrate various foundation types (excluding piles) that may be used to support a building.
Investigate and analyse the advantages and disadvantages of these various systems including
the way in which they transmit the loads to the ground. Suggest when it may be appropriate
to use each of the foundation types.
4.1.
Strip Foundation (see appendix 1 & 2 for detail) (trench foundations are very similar to
strip foundations, differing mainly in thickness of foundation)
a. Required for:
i. External walls
ii. Separating walls
iii. Chimney breasts
iv. Piers
v. Internal loadbearing walls
b. Dimensions are 150mm -500mm thick depending of bearing stratum (refer to
appendix 2 for more information)
c. Material
i. Cast in-situ concrete (OPC or SRPC)
ii. pre-cast concrete (OPC or SRPC)
d. Concrete shall be of a mix design which is suitable for the intended use, items to be
taken into account include:
i. strength to safely transmit loads
ii. durability against chemical or frost action
e. Normal depth of 1m
f. Not recommended for soils with low bearing capacity and should be laid at a depth
where the foundation can transfer the required load to good bearing stratum
g. Except where strip footing sit on bedrock, foundations should be taken to a
minimum of 450mm below ground
h. Reinforcement can be added
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i.
When taking the foundations to the required depth the water table may have to be
taken into consideration
j.
Brownfield site ground maybe hazardous therefore the foundation should be
designed by an engineer
i. Designed in accordance with
1. BS EN 1991-1-1
2. BS EN 1991-1-3
3. BS EN 1991-1-4
4. BS 648.
5. BS 8500-1
6. BRE Special Digest 1
RIBA (2010), NHBC (2011), Hodgkinson, A (1986)
Strip Foundations
Advantages
Disadvantages
When Required
Shallow foundations,
Limited load carrying ability
In ground of medium to good
therefore little excavation
due to foundation depths and
bearing stratum, on domestic
needed.
design, therefore only suited
scale developments,
to small/medium
underneath loadbearing walls,
developments.
separating walls, chimneys,
Economically cheap due to
the narrow, shallow design.
Little to no impact on
Not ideal for framed
construction.
neighbouring properties.
Sulphate Resisting Portland
Cement (SRPC) can be used in
place of Ordinary Portland
Cement (OPC) to cope with
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Weak against uplift forces,
piers and internal loadbearing
walls.
To carry light loads
wind forces and earthquake
forces.
Weak in stratum of loose sand
Page 8
sulphur attack from soils.
or gravel.
Riley et al.(2009)
The continuous narrow trenches excavated for the Strip foundations are suited to continuous
load bearing walls as opposed to point loads. Not intended to support building higher than 3/4
storeys. The narrow trenches would need to be taken to a depth where the foundation could
transfer the load to suitable stratum, at depth the excavated trenches would require supports
to prevent caving in. Working space needed of 600mm (under building regulations) for health
and safety would need to be provided for workers to carry out work, the sided of the excavated
working space trenches requiring support. Once all required work has been carried out the
working space trenches would have to be backfilled.
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4.2.
Pad foundations (see Appendix 3)
a. An alternative to strip foundations for framed structures
b. Required for:
i. External walls
ii. Separating (party) walls
iii. Chimney breasts
iv. Piers
v. Internal loadbearing or masonry walls
vi. Sleeper walls
c. Material
i. Cast in-situ concrete (OPC or SRPC)
ii. Reinforcement
d. Thickness designed to transmit the load at a 45° angle through the Pad to minimise
tensile stresses on the soffit of the foundation
e. Transmit the load to the bearing strata through individual foundations
f. Concrete shall be of a mix design which is suitable for the intended use, items to be
taken into account include:
i. strength to safely transmit loads
ii. durability against chemical or frost action
g. Reinforcement can be added to carry the tensile stresses and required loads
h. Shear reinforcement can be added to avoid punching failure
i.
Not recommended for soils with low bearing capacity and should be laid at a depth
where the foundation can transfer the required load to good bearing strata
j.
Brownfield site ground maybe hazardous therefore the foundation should be
designed by an engineer
i. Designed in accordance with;
1. BS 648
2. BS EN 1991
3. BS EN 1997-1
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4. BS EN 1992
5. BS 10175
NHBC(2011), RIBA (2010), Hodgkinson, A (1986)
Pad Foundations
Advantages
Disadvantages
When Required
Shallow foundation
Foundation size can be a very
Ideal foundation for point
Requires little excavation.
large to cope with high point
loads from framed
loads.
buildings when bearing
Can be designed to
accommodate tight sites.
capacity of ground is
Limited foundation suitability to
suitable a shallow depths.
point loads of framed buildings.
Economic due to control of
foundation size.
Separate foundations make this
design weak against differential
Reinforcement for tension and
settlement that may affect the
shear can be added.
building.
Concrete mix can use SRPC in
Deep excavations for
place of OPC
foundations would require
support to prevent caving in.
Weak against uplift forces, wind
forces and earthquake forces.
Riley et al.(2009)
Pad foundations are suited to a framed construction however the ground type described in the
brief and the heavy load of the 5 story building would require this usually shallow foundation to
be taken deeper to better bearing stratum, thus eliminating the economic advantage of this
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foundation. The foundation size would have to be enlarged to cope with the high point loads.
Additional costs occur for supporting the excavations to prevent cave-ins. As the site is a
brownfield site SRPC my need to be introduced thus increasing the material cost.
Hodgkinson, A (1986)
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4.3.
Raft foundations (see appendix 4)
a. Used in ground with very low bearing capacity or where excessive variations in
ground conditions would cause unacceptable differential settlements
b. Recommended for;
i. External walls
ii. Separating walls
iii. Chimney breasts
iv. Piers
v. Internal loadbearing walls
vi. Sleeper walls
c. Recommended when Strip or Pad foundations occupy more than 50% of the floor
area
d. Requires reinforcement to carry the tensile, load Steel reinforcing fabric should
comply with BS 4483
e. Suitable for projects where there is a shallow water table
f. Material
i. Cast in-situ concrete (OPC or SRPC)
g. Approved Document C4 requires the minimum quality of the concrete to be at least
mix ST2 of BS 5328-1
h. Concrete shall be of a mix design which is suitable for the intended use, items to be
taken into account include:
i. strength to safely transmit loads
ii. durability against chemical or frost action
i.
Brownfield site ground maybe hazardous therefore the foundation should be
designed by and engineer
i. Designed in accordance with;
1. BS 648
2. BS EN 1991
3. BS EN 1997-1
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4. BS EN 1992
5. BS 10175
NHBC(2011), RIBA (2010).
Raft Foundations
Advantages
Disadvantages
When Required
Financially cheap due to the
Weak when supporting point
Lightweight structures on
combined use of the
loads, specific treatment
poor ground with low
foundation as the floor.
required.
bearing capacity.
Shallow depth of foundation
Susceptible to edge erosion.
Used in areas with mixed
means little excavation.
bearing capacity usually
filled ground.
Can cope with poor/mixed
ground conditions.
Riley et al.(2009), Hodgkinson, A (1986)
Raft foundations are ideal foundation choice to support light weight buildings (3/4 stories high).
The design provides an economical advantage that is the dual use of the raft as the ground floor
concrete slab. The foundation is suited to traditional buildings in grounds of poor/mixed
bearing stratum. The raft provides very good protection against differential ground settlement,
earthquakes and heave due to the design. The raft would traditionally not suit a famed building.
The raft can be designed to accommodate framed structures however they were not intended
to cope with high point loads. The concrete mix can have SRPC added to help resist chemical
attack.
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5.0.
Report 2 – Deep Foundations
Illustrate various types of pile foundation that may be used to support a building. Investigate
and analyse the advantages and disadvantages of these various systems including the way in
which they transmit the loads to the ground. Suggest when it may be appropriate to use each
of the pile types
5.1.
Friction/Driven piles/Displacement piles (see appendix 5)
a. Are piles driven into the ground, they derive their bearing capacity from skin friction
and/or adhesion
b. Required for;
i. External walls
ii. Separating walls
iii. Chimney breasts
iv. Piers
v. Internal loadbearing or masonry walls
vi. Sleeper walls
c. Suited to loose and moisture bearing granular soils
d. Material
i. Reinforced concrete
ii. Prestressed concrete
iii. Steel
e. Unsuited to ground containing boulders or obstacles
f. Brownfield site ground maybe hazardous therefore the foundation should be
designed by and engineer
i. designed in accordance with;
1. BS 648
2. BS EN 1991
3. BS EN 1997-1
4. BS EN 1992
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5. BS 10175
g. May be accompanied by a reinforced ring beam or pile caps to provide stability
against forces and help transfer loads
NHBC(2011), RIBA (2010), Biddle et al.(2002)
Friction/Driven piles/Displacement piles
Advantages
Disadvantages
When Required
Can transfer load in variable
Problematic when dimensional
Sites with poor ground
ground conditions.
stability of the ground is an
conditions.
issue.
Can transfer loads to deep
bearing stratum
Suitable to tight sites.
Soils that have low
Problematic when there is
bearing capacity but offer
demolition debris or boulders in
good friction forces.
the ground.
Bearing stratum is deep
Made off site and quality
Noisy installation method can
maintained due to factory
cause environmental impact
below the surface.
production.
Vibration can affect neighboring
There is no evidence that
properties
Steel piles are susceptible to
corrosion by the action of
Can cause ground heave
sulphur reducing bacteria
(<0.03mm corrosion per
annum).
No excavation required.
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No need to support excavated
holes.
Suited to framed construction.
Harrison et al.(2012), Riley et al.(2009), Biddle et al.(2002), Technical Committee B/517 (2009)
Friction Pile foundations are uniformly distributed columns driven into the ground via the
repeated dropping of a weight onto the head of the pile, to reach the required depth and
transmit the required building loads to good bearing stratum. Pile foundations would normally
be used when ground conditions are not suitable to economically support reason for traditional
foundations. Friction piles cope well with live loads, dead loads, wind loads, earthquakes and
uplift. They can cause problems such as heave. The piles are compatible with framed buildings
and designed to carry loads of light to heavy weight structures. Steel piles have a very high
resistance to sulphur attack or SRPC can be added to concrete mixes. Piles are ideal for
brownfield sites that may have had previous buildings on the site. Reinforcement can be added
to cope with the horizontal forces. There is an economic advantage not excavating material.
Chudley, R., et al. (2010), Hodgkinson, A (1986)
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5.2.
End-bearing piles/Bored piles/Replacement piles (see appendix 6)
a. Holes bored into the ground and filled with concrete
b. Required for;
i. External walls
ii. Separating walls
iii. Chimney breasts
iv. Piers
v. Internal loadbearing or masonry walls
vi. Sleeper walls
c. The pile transmits the load through the pile to the bearing strata which the pile is in
contact with
d. Suited to poor/mixed ground
e. Material
i. In-situ concrete (OPC or SRPC)
ii. Reinforced
f. Brownfield site ground maybe hazardous therefore the foundation should be
designed by and engineer
i. Designed in accordance with;
1. BS 648
2. BS EN 1991
3. BS EN 1997-1
4. BS EN 1992
5. BS 10175
g. May be accompanied by a reinforced ring beam or pile caps to provide stability
against forces and help transfer loads from the building to good bearing stratum
NHBC(2011), RIBA (2010), Biddle et al.(2002), Hodgkinson, A (1986)
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Large diameter bored piles
Advantages
Disadvantages
When Required
Can transmit heavy loads.
Require reasonably good soil
Heavy buildings with large
content to avoid bore hole
loads.
Larger diameter of piles mean
collapsing.
less piles needed.
No need to support bore hole
When there is a risk of
Large plant needed to
damage to surrounding
excavate earth.
buildings through vibration.
as concrete replaces the void
created.
Bearing stratum is deep below
the surface.
Almost vibration free.
Almost noise free.
Not susceptible to boulders or
debris below ground.
Can transfer loads to deep
bearing stratum on tight sites.
Riley et al.(2009), Biddle et al.(2002), Technical Committee B/517 (2009)
End-bearing piles are suited to sites where there is a requirement to transfer large loads to a
bearing stratum that is too deep for other foundations. The boring process eliminates the noise
and vibration factor. Bored pile diameters range from 450mm to 1200mm so fewer piles would
be needed if larger piles were used. Piles can be combined with pile caps or a ring beam to
increase stability to the structure. Suited to framed structures and ideal for dealing with point
loads and they are very strong in compression. Reinforcement can be added to cope with the
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horizontal forces. SRPC can be added to the concrete mix to combat the sulphate chemicals in
soils. Piles are ideal for brownfield sites.
NHBC(2011), Hodgkinson, A (1986)
6.0. Decision matrix (showing the value you each foundation through a rating system of 1-5
in which 1 – poor and 5 – ideal)
Information/requirements Strip
known
Pad
Raft
Driven Pile
Bored Pile
Foundation Foundation Foundation Foundation Foundation
(weighting)
(weighting)
(weighting)
(weighting)
(weighting)
1
1
5
5
5
five storey office building
2
2
3
5
5
brownfield site
3
3
2
5
3
city centre
4
4
4
2
4
possible obstructions
5
5
5
3
5
15
15
19
20
22
Bed rock 8m below
ground
within the ground
Total
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7.0.
Conclusion
After analysing the various foundations and processing them into the decision matrix, Bored
pile foundations appear to be the most suitable, however there is very little information known
at this stage and it would be possible to use raft, driven piles or bored piles on such a project.
Strip and pad foundation would not be suitable sue to land, size of building and loads the
foundations would have to cope with. Raft foundation although used mainly for light weight
structures could be designed to cope with greater loads. The building design is not known and it
would be suggested if this building would be a framed building then it would be best not to use
raft foundation as its design is traditionally weak in supporting point loads, the raft would cope
with the land and deep bearing stratum issue. Driven piles appear to be a better option
according to the decision matrix as they are designed to cope with heavier loads. Driven piles
are ideal for tight sites as they require no excavation, there would be an economical benefit to
this too. The driven pile foundations are not perfect, they are unsuitable for use in ground with
boulders or debris below ground, which the pile may hit and be pushed off course, in this case
it would be a cost to, have the pile removed and relocated, or excavate the boulder/debris, and
drive the pile again. The decision matrix shows bored piles have come out as the favourite
choice, the reason for this is its ability to cope with the loads specified for the building. They
can reach the depths of the bedrock, the reduced vibration and noise in comparison to the
driven pile are to the advantage of the bored piles, this is a city centre site and therefore likely
to have neighbouring buildings, which with driven piles may be subject to heave or settlement
displacement. With bored piles the client would have less chance of falling foul to disturbing
the neighbouring properties. More information at this stage is required in order to properly
select the right foundation such as the LCR. Based on the information provided either of the
pile foundation types would be suitable.
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Reference
Biddle,A.,Yandzio,E (2002). Specifiers’ Guide to Steel Piling. Berkshire: The Steel Construction
Institute. 1-46.
Charles, J (2004). Building on brownfield sites: reducing the risks. Watford: BRE Bookshop. 1-8.
Chudley, R., Greeno, R (2010). Building Construction Handbook, Incorperating Current building
& Construction Regulations. 8th ed. Oxford: BSIElsevier Ltd. p206-319.
European committee for standardisation (2007). Precast concrete products — Foundation piles.
Brussels: BSI. 1-44.
Harrison,H.,Trotman,P (2012). Foundations,basements and external work. London: BRE Building
elements. 1-249.
Hodgkinson, A (1986). Foundation Design. London: Architectural Press Ltd. p15-81.
NHBC (2011). NHBC Standards: Land Quality - Managing Ground Conditions Chapter 4. 1. 4th
ed. England: National house building council. 1-16.
RIBA (2010). Structures Approved Document A. London: NBS. p1-45.
RIBA (2010). Fire Safety Approved Document B, Volume 2: Buildings Other Than Dwelling
Houses. London: NBS. p1-150.
RIBA (2010). Site Preparation and Resistance to Contaminants and Moisture Approved
Document C. London: NBS. p1-40.
RIBA (2010). Toxic Substances Approved Document D. London: NBS. p1-5.
Riley,M.,Cotgrave,A (2009). Construction technology 2:Industrial and commercial building. 2nd
ed. England: Palgrave. 109.
Technical Committee B/517 (2003). Concrete — Complementary British Standard to BS EN 2061 — Part 1: Method of specifying and guidance for the specifier. London: BSI. p1-40.
Technical Committee B/517 (2009). Code of practice for noise and vibration control on
construction and open sites – Part 2: Vibration. 3rd ed. London: BSI. p1-90.
Technical Committee B/517 (2011). Structural design of low-rise buildings Part 1: Code of
practice for stability, site investigation, foundations, precast concrete floors and ground floor
slabs for housing. 3rd ed. London: BSI. p1-58.
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Appendix 1
Image taken from: NHBC(2011)
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Appendix 2
Image taken from:
http://www.google.co.uk/imgres?imgurl=http://www.thebeamlockcompany.co.uk/images/Bea
mlockFoundations.jpg&imgrefurl=http://www.thebeamlockcompany.co.uk/technical.html&h=602&w
=566&sz=94&tbnid=1QOdwPHCDx63HM:&tbnh=90&tbnw=85&prev=/search%3Fq%3Dpad%2Bf
oundations%2Bdetails%26tbm%3Disch%26tbo%3Du&zoom=1&q=pad+foundations+details&us
g=__-kM0aIizEOTaO-c3ub9h3ytAV8g=&docid=WTfGBMNXwOLKM&hl=en&sa=X&ei=J_C7UJGEDsWg0QXxlIGoDA&ved=0CC4Q9QEwAA&dur=0
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Appendix 3
Image taken from:
http://www.google.co.uk/imgres?imgurl=http://www.thebeamlockcompany.co.uk/images/Bea
mlockFoundations.jpg&imgrefurl=http://www.thebeamlockcompany.co.uk/technical.html&h=602&w
=566&sz=94&tbnid=1QOdwPHCDx63HM:&tbnh=90&tbnw=85&prev=/search%3Fq%3Dpad%2Bf
oundations%2Bdetails%26tbm%3Disch%26tbo%3Du&zoom=1&q=pad+foundations+details&us
g=__-kM0aIizEOTaO-c3ub9h3ytAV8g=&docid=WTfGBMNXwOLKM&hl=en&sa=X&ei=J_C7UJGEDsWg0QXxlIGoDA&ved=0CC4Q9QEwAA&dur=0
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Appendix 4
Image taken from:
http://www.google.co.uk/imgres?imgurl=http://www.thebeamlockcompany.co.uk/images/Bea
mlockFoundations.jpg&imgrefurl=http://www.thebeamlockcompany.co.uk/technical.html&h=602&w
=566&sz=94&tbnid=1QOdwPHCDx63HM:&tbnh=90&tbnw=85&prev=/search%3Fq%3Dpad%2Bf
oundations%2Bdetails%26tbm%3Disch%26tbo%3Du&zoom=1&q=pad+foundations+details&us
g=__-kM0aIizEOTaO-c3ub9h3ytAV8g=&docid=WTfGBMNXwOLKM&hl=en&sa=X&ei=J_C7UJGEDsWg0QXxlIGoDA&ved=0CC4Q9QEwAA&dur=0
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Appendix 5
Image taken from:
http://www.google.co.uk/imgres?q=friction+driven+piles&um=1&hl=en&sa=N&tbo=d&biw=13
66&bih=648&tbm=isch&tbnid=lk5DNHOkKOqPNM:&imgrefurl=http://www.substruck.ie/ourservices/foundationrepair/piling&docid=qzfj53dH8b7PKM&imgurl=http://www.substruck.ie/wpcontent/themes/substruck/pictures/frictionpile.jpg&w=604&h=367&ei=duq7UKjLBu7M0AWar
4HQCw&zoom=1&iact=hc&vpx=1035&vpy=375&dur=1369&hovh=175&hovw=288&tx=109&ty
=121&sig=104003884147091334153&page=1&tbnh=131&tbnw=216&start=0&ndsp=25&ved=1
t:429,r:24,s:0,i:160
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Appendix 6
Image taken from:
http://www.google.co.uk/imgres?q=friction+driven+piles&um=1&hl=en&sa=N&tbo=d&biw=13
66&bih=648&tbm=isch&tbnid=lk5DNHOkKOqPNM:&imgrefurl=http://www.substruck.ie/ourservices/foundationrepair/piling&docid=qzfj53dH8b7PKM&imgurl=http://www.substruck.ie/wpcontent/themes/substruck/pictures/frictionpile.jpg&w=604&h=367&ei=duq7UKjLBu7M0AWar
4HQCw&zoom=1&iact=hc&vpx=1035&vpy=375&dur=1369&hovh=175&hovw=288&tx=109&ty
=121&sig=104003884147091334153&page=1&tbnh=131&tbnw=216&start=0&ndsp=25&ved=1
t:429,r:24,s:0,i:160
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Appendix 7
Image taken from: NHBC(2011)
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Appendix 8
Image taken from: NHBC(2011)
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Appendix 9
Image taken from: http://www.buildingscience.com/index_html
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