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CEMicircularThe College of Estate Management compiles this bulletinfor current and former students as an aid to your studiesand future careers.

CEMicircular  covers all courses and includesinformation about important developments and topicalissues in the world of surveying and property. You should not, however, rely on the extracts in CEMicircular  as your only source of information. They will seldom offer morethan a brief summary of a new topic or recent issue and some points are bound to be omitted, perhaps giving undueemphasis to the material included. You are therefore urged to read as widely as possible, including making use of the

Internet, and it is vitally important that current studentsstudy the course material. This could make the difference

 between superficial knowledge and real understanding.To help you keep up to date, look out for the following

captions against items:

■ CEMicircular WebWatch gives details of related websites where additional information can be sourced.

■ Latest Research indicates material that has beengenerated by recent research, including projects carried out by CEM and other institutions.

Editor’s noteThe editor of this circular is Gaye Pottinger, Senior Research

Officer at CEM. She would be pleased to hear your views

and comments on its structure, content and presentation.

Contributions or suggestions of material for inclusion are

also welcome. Please write to Gaye Pottinger at the College

address below, or email to: k.g.pottinger@cem.ac.uk .

Subscription to CEMicircularCEMicircular  is produced twice a year, in the spring and autumn. It is sent to all students on CEM courses, staff, CPD

subscribers and members of the Property People’s Network (PPN), which is open to CEM alumni. To join PPN seewww.ppnonline.co.uk.

CopyrightThe extracts from journals in this circular are reproduced by

 permission of the publishers. So as not to abuse this permission, the College asks that anyone wishing to makecopies of any of the articles should first contact the editor of CEMicircular.

Contents Page Building■ Roof design 2■ Siphonic drainage 5■ Structural movement 6■ Historic environments and the DDA 12■ Book – historic buildings measured surveys 14

Construction■ Defined provisional sums 15■ Managing risk 16■ Settling claims 17■ Causation 18■

Corporate social responsibility 19■ The Milau Viaduct, France 21■ Public procurement 24

 Development■ Affordable housing quotas 25■ Sports development NY style 28

 Finance■ Cross border investment and due diligence 29■  New accounting rules 30

 Law■ Confidentiality and legal privilege 32■ Liability insurance 34■ Civil law and common law 35■ UK Freedom of Information Act 37

 Management■ Adverse possession 39■ Service charges 41

 Planning■ PPG3 Planning for mixed communities 42■ Planning obligations 44■ Planning application approvals 45

 Property■ Actors and property 46■ Office building obsolescence 47

 Residential ■ Evicting tenants and mental health 48■ Leasehold reform changes 49■ Right to Buy valuation 52

 Rural ■ Valuing wildlife, recreation and leisure 53■ A rural village 58

Valuation■ Confidentiality of rents 60■ Rent review arbitration award 61■ Rent-free periods and fitting out 62

 Notices■  New researchers 64

■ Book – Real Estate and the New Economy 64■ Keeping it in the family 65■ Hong Kong accreditation 65■ Becoming a licensed home inspector 65■ Student assignment queries 66

Vol 11 No 1 Spring 2005

Whiteknights, Reading, Berkshire, England, RG6 6AW 

Tel 0118 986 1101 Fax 0118 975 0188/5344

Published by The College of Estate Management

and issued to all its students and staff

Patron: HRH The Prince of Wales

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BUILDING

Building

Roof design

When designing a roof it is important to get the structure

right – to ensure it will not collapse or blow away. This

article examines the basics of good design, including a look 

at wind loading on photovoltaic panels and consideration of 

snow loading. The relevant British Standards covering many

aspects of roof design are highlighted, plus the transitional

arrangements to new European standards that came into

effect at the end of 2004. The author, Keith Roberts , is a

chartered civil and structural engineer based in

Oxfordshire, UK, who specialises in roofing and cladding

(Architects Journal, aj focus , November 2004 pp.19–23).

The interest in mounting solar-energy systems on the top of exposed roofs has raised questions about the risk of them

 blowing off. Experience tells us that lightweightcomponents, such as television aerials and satellite dishes,are often the first to be damaged or come loose during asevere wind storm. When placing lightweight photovoltaic(PV) panels on a roof, it is important to ensure that they willstay up there securely for the life-time of the building. TheBuilding Research Establishment (BRE) has recently

 published Digest 489, giving recommendations for calculating wind loading on PV panels.

The digest was published in August 2004 following work undertaken as part of a Partners in Innovation (PII) projectfunded by the Department of Trade and Industry. The PII

 project team included manufacturers, PV specialists, tradeassociations and the BRE.

To determine whether or not a solar panel will be blownoff a roof requires an estimate of the applied wind pressure,which can then be used to check that the applied loads on thefixings and roof structure below are not excessive. Thestarting point is to determine the wind pressure for the site.The digest helpfully gives a simplified method, based on aminimum amount of information known about the site. For example, the dynamic wind pressure for a 10m-tall building

on a level site in Nottingham would be 1.2kN/m2.The digest gives recommendations for the coefficients of 

 pressure for PV modules mounted in four different ways.The panels are usually aligned at a slope of around 350 tothe horizontal and facing south. The digest gives moredetailed information about the selection of the coefficientsand the assumptions made. Arrays of PV tiles are considered to be ‘air-permeable’ where the individual PV units are nomore than six times the area of the surrounding individualroof tiles. For a solar panel mounted on a stand near the roof edge, the peak coefficient of pressure would be –1.8, actingin suction.

Knowing the dynamic pressure for the site, thecoefficient of pressure and the area of each PV moduleallows you to calculate the design wind pressure. For theworked example, the wind suction-loading acting on a singlesolar panel – each approximately 2 × 0.6m, or 1.2m2 in area,mounted near the edge of the roof located in Nottingham – 

would be 1.2 × 1.8 × 1.2 = 2.6kN. This is equivalent to265kg of weight acting in suction. One way to picture this is

to imagine roughly five 50-kilo bags of cement actingupwards, trying to lift the solar panel up off the roof, Thewind can exert large forces on roof cladding and components.

PV modules mounted on roofs are often in exposed locations and will be subjected to buffeting by gusts of wind throughout their lifetimes. It’s important to stop themworking loose and falling into public areas, so assessing the

 performance of PV installations under wind loads isimportant. BRE’s Digest 489 is welcomed in giving the basicinformation for designers and roofers to assess these risksand is essential reading for those involved in this specialist

market.Changing the code within the next few years, the British

Standard Code of Practice for Wind Loading on Buildings(BS 6399 Part 2) is to be replaced by the new Eurocode 1:‘Actions on Structures – Part 1.4 General Actions – Wind Actions’ (BS EN 1991–1-4). This standard has now beenapproved formally by the CEN (European Committee for Standardisation) and it is expected that the full document,including the UK National Annex, will be published by theend of 2004.

This will be followed by a transition period, with the twostandards running in parallel. As with the previouschangeover from CP3 to BS 6399, time and resources willhave to be allocated for training in understanding the newEurocode and putting it into practice.

Specifications for roof systems that refer to the current standard 

and give site parameters such as basic wind speed, altitude

and terrain will need to be amended, of course.

Let it snow

Apparent changes in weather patterns in recent years havereduced the number of times we have experienced heavyfalls of snow during the winter months. However, the need remains to assess the design snow-load in accordance withBS 6399 Part 3 and ensure a roof structure can withstand this. The UK is considered to have a maritime climate. Thismeans that most parts of the country will experience amaximum snow-load condition resulting from a singlesnowfall rather than as a result of snow accumulation over several months. The British Standard is based on this

 principle of a single snow event.Essentially, there are two basic types of snow-loading:

the uniform snow-load dependent on location, altitude and roof pitch; and an asymmetric snow-load resulting from theredistribution of snow by the wind, causing drifting intovalleys and against parapets and obstructions. The weightdensity of snow in a local drift is assumed to be 2kN/m 2. A

method for estimating the snow-load shape coefficients for asymmetric snow-loading is given in the British Standard,which was last reissued in September 1996 with further explanation in BRE’s Digest 439. One effect oftenencountered on large building complexes with lightweight

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roof constructions is that additional purlins are necessary onlower roofs adjacent to taller structures to support localsnow drifts, which can be as much as 2kN/m2 in England and Wales.

Scotland experiences higher snowfalls each winter. Onsteep-sided metal roofs in urban areas, there is the risk of 

snow building up and slipping, falling on to pedestrians atground level. This can be overcome by fixing snow guardsaround the perimeter of the roof, a detail that is common inScandinavia and Canada. In the UK, Corus manufacturessnow guards specifically for attaching to Kalzip roofingsystems. The long-range weather forecasts for a severewinter may be a timely reminder to be aware of the potentialfor snow-loading on our roofs.

 ■

Useful contacts

BRE 01923 664000

BSI 020 899 69001Corus Building Systems 01942 295500

Imagination Solar 084S 458 3168PV Systems 029 208 20910

Solar Century 020 780 30100

Keith Roberts can be contacted at

www.robertsconsuiting.co.uk

FURTHER INFORMATION■ Approved Document A, Structure (2004 Edition), Building

Regulations (www.odpm.gov.uk)■ BS6399Part1:1996, ‘Design loading for Buildings, Part 1:

dead and imposed loads’■

BS6399Part2:1997, ‘Design loading for Buildings, Part 2:wind loads’ (corrected and reprinted 2002)■ BS 6399 Part 3:1988, ‘Design loading for Buildings, Part

3: imposed roof loads’ reprinted 1997)■ BS5268: Part 2: 2002, ‘Structural use of timber:

permissible stress design’■ BS 5268: Part 3: 1998, ‘Structural use of timber: trussed

rafter roofs’■ BS S950: Part 5: 1995, ‘Structural. use of steelwork:

design of cold formed thin gauge sections’■ B58118: Part 1: 1991, ‘Structural use of aluminium’■ BS8110:Part1:1997, ‘Structural use of concrete’■ BS 5534: 2003, ‘Slating and tiling (including shingles)’■ BS 5427 Part 1 1996, ‘The use of profiled sheet for roof

and wall cladding on buildings’■ BS 6229: 2003, ‘Flat roofs with continuously supported

coverings – Code of practice’ I

 Important note: For detail design, reference should be made

to the full published documents.

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TABLE: Basics of good roof design: structural issues

LOADING Question: What are the magnitude and loading of the applied roof loads?

Units: kN/m2

Load shapes Uniformly distributed load (udl); point load on any square with 125mm side

Load type Factors Typical values Source

Dead material, thickness interlocking concrete roof tile = 0.48–0.55 kN/m2 BS 6399 – 1 (2)

 1.2mm thick profiled steel sheet = 0.12 kN/m2

 1.5mm PVC membrane = 0.03 kN/m2

Live with access udl = 1.5 kN/m2  , point = 1.8 kN BS 6399 – 3 (4)

no access udl = 0.6 kN/m2  , point = 0.9 kN

Wind location, altitude, single-story pitch roof in London, field area = –0.7 kN/m2 BS 6399 – 2 (3)

topography, building height five-storey flat roof on hillside in Glasgow, eaves = –6 kN/m2

and shape, local zones

Snow location, altitude, roof shape, Lowland England, udl = 0.3 kN/m2 BS 6399 – 3 (4)

obstructions to drifting Highland Scotland, drifting = 8 kN/m2

Services lighting and other building 0.25–0.50 kN/m2

services, water tank 230 lit re (50 gallon) = 2.3 kN/m2

DECK Question: Will there be proper support to the roof component?Why? to give proper support to the roof component and to allow fixingComponents supported: tile, membrane, insulation, vcl, metal cladding

Load combinations: (dead + live + services), (dead + snow), (dead – wind)

What to check: – factored flexural strength > factored applied bending stress

– (D + L) deflection < span/200, (D + W) deflection < span/90 (for profiled metal sheet (11))

Factors of safety: refer to BS for detail

Material Typical spans Size, thickness Source

Tiling batten 0.3–0.6m 50 × 25mm BS 5534 (10)

Plywood 0.3–0.6m 18mm, 25mm BS 5268: Part 2 (5)

Steel deck 1.5–8m 0.7 to 1.5mm thick, BS 5950: Part 5 (7)

35 to 200mm deep profile

Aluminium deck 1.2–6m 0.9 to 1.5mm thick, BS 8118 (8)

35 to 200mm deep profile

Precast concrete plank 3–13m 110 to 300mm BS 8110 (9)

In-situ concrete slab 3–13m 110 to 300mm BS 8110 (9)

Stressed skin design: check adequacy of connections Important to refer to manufacturer’s published literature

SUBSTRUCTURE Question: Will there be proper support to the roof deck?

Why? to give proper support to the roof deck and allow fixing

What to check: – factored flexural strength > factored applied bending stress

– (D + L) deflection < 0.003 × span (for timber joists (5))

Load combinations: (dead + live + services), (dead + snow), (dead – wind)

Material Typical spans Thickness, depth Source

Timber joist 1.5–5m 40 × 100 – 75 × 225mm BS 5268: Part 2 (5)

Timber purlin 1.8–3m 50 × 150 – 75 × 225mm BS 5268: Part 2 (5)

Timber truss 3–15m 40mm thick BS 5268: Part 3 (6)

Steel Z section 3–10m 125–275mm BS 5950: Part 5(7)

Steel RSA, UB or RHS 3–15m 127–914mm BS 5950: Part 1

Precast concrete beam 3–15m 150–900mm BS 8110 (9)

Important to refer to manufacturer’s published literature

ATTACHMENT Question: Will the roof blow away?

Why? to prevent wind damage

What to check: consider the load path in which the applied wind load acting on the roof component is transferred

down to the foundations. Check each link of the chain to ensure that the factor of safety is

adequateHigh-r isk roofs: exposed site locat ion, tall buildings, lightweight construction, large opening into spaces below

roof

Load combination: (dead – wind)

Other information required: pull-out strength of fasteners and materials being joined

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Siphonic drainage

Siphonic roof drainage systems were first installed in

Scandinavia in the late 1960s and are now used worldwide

as the best way to drain large roofs. Unfortunately, a

number of high profile failures in the 1990s caused doubtsabout the performance of siphonic systems that are

misleading, because the problems were to do with poor 

installations, explains Dr Malcolm Wearing , secretary of 

the Siphonic Roof Drainage Association (SRDA)

(Architects Journal, aj focus , November 2004 pp.26–32).

Siphonic drainage is actually very simple in principle, and all systems work in exactly the same way. Baffle platesinserted in the outlets restrict air entering the top of thedrainage system, which, when combined with carefully sized 

 pipework, causes the system, horizontal and vertical, to run

full.In a very similar way to a simple tube siphon (such asyou would use to empty a fish tank), the action of water dropping down the downpipe will cause a negative pressureto form at the top. This pressure can be harnessed to suck water along a collector pipe installed horizontally,connecting the outlets at high level.

The benefits this gives are:■ each gutter will have only one or two downpipes, and 

these can be located at the end of the building,allowing free use of floor space by eliminatingdownpipes and therefore reducing columns;

■ the horizontal collector pipe can be very close to thegutter, allowing full use of internal space;

■ underground drainage can be eliminated internally ina building, and can be reduced significantlyexternally, which can provide considerable costsavings and enhance construction programmes on allsites – particularly on contaminated ones; and 

■ for sites with a requirement for SuDS (sustainabledrainage systems), siphonic drainage will allow water to be delivered at a designated point at shallowdepth, which can reduce the construction costssignificantly, especially for pond-based solutions.

What to specifyWhen specifying siphonic drainage, there are a number of key factors that must be covered. These are:

■ Rainfall intensity – the rainfall levels should bedetermined from BS EN 12056-3: 2000, using the projected building life and a suitable factor of safety.The contents of the building should be considered aswell as the building type. The more years that arespecified, the lower the risk to the building will be, but the more expensive the system, so there is alwaysa balance to suit the acceptable level of risk.

■ Filling time and gutter calculations – it is vitally

important that the siphonic contractor providescalculations to show that the system will fill withinone minute, and that the gutter will function correctly – meaning it will not over-top. In the UK, the designrainfall event (the most intense period of a storm) is

two minutes, and so a siphonic system must begin tofunction within half this time or the roof could flood.In the past some companies have claimed that their systems do not need to fill to operate, but this issimply not correct. Gutter calculations should be toBS EN 12056-3: 2000, using outlet data from a

British Board of Agrement (BBA) certificate or other third-party source.

■ Pipework – the majority of siphonic drainagesystems in Britain use high-density polyethylene(HDPE) pipework. This can be connected either byusing electrofusion couplings, which are heated byinternal elements, or by butt-jointing, where the cutends of the pipe are melted and then forced together under pressure to make a joint. Butt joints should only be made using a machine incorporating a jig and control system to monitor the temperature, time and  pressure required. Site butt-jointing of HDPE should 

only be allowed in a specification if ‘factory’conditions are set up on site so that consistent qualitycan be guaranteed. Metal pipe systems (cast-iron,galvanised or stainless steel) can also be used for siphonic drainage. The specification should detail thatinstallation should be according to the manufacturer’srecommendations for negative pressure.

Don’t bother to specify a ‘self-priming outlet’ – they all self- prime.

Where should siphonics be specified?

The answer is that almost any building can be drained siphonically, but with the following provisos:

■ large industrial, storage or retail buildings will showmuch greater benefit gains over gravity drainage – infact, it would be almost impossible to drain some of these buildings by gravity;

■ the gutters or flat-roof areas must be large enough toaccept a siphonic outlet, and must have adequateaccess for maintenance – gutters in inaccessiblelocations might not be so suitable;

■ all drainage can produce unwanted noise – in areassensitive to sound, siphonic systems, like gravity pipework, may need acoustic insulation.

What can go wrong?

In the 1990s there were a number of high-profile failures of siphonic roof drainage systems, which led to the technology becoming suspect in some people’s eyes. This is, however, agreat shame, as in all cases poor design was the cause, not afailure in the system. The key reasons for failure were:

■ One or two companies set up in the industry withoutan adequate level of technical knowledge and designed systems where the negative pressure was sogreat that pipework actually collapsed under the

 pressure, causing serious flooding of the building.This would not have happened if the pipework had  been designed using suitable software, such as is used  by all members of the newly set-up Siphonic Roof Drainage Association (SRDA).

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Structural movement

This article is a version of Clive Richardson’s annual

Christmas lecture to the RICS / College of Estate

 Management Postgraduate Conservation Programme at 

 Reading in 2004. In it he reviews the seven causes of structural movement by reference to changes in building

techniques over the centuries, and addresses the question:

should we be concerned about structural movement in

buildings?

Clive Richardson is a structural engineer and technical

director of Cameron Taylor, Bedord. He is also engineer to

the Dean and Chapter of Westminster Abbey, visiting

lecturer at the Architectural Association, and technical

secretary of the ICE/IStructE CARE Panel (Conservation

 Accreditation Register for Engineers). ( Building

Conservation Journal  , Number 37, 2004, pp.6-11.)

Introduction

In the immediate post-war years, when we were grateful for any accommodation which had survived the Blitz, attitudesto odd cracks were relaxed. When redecorating, my father would gleefully summon us children to see finger-widecracks discovered beneath the wallpaper, beforeceremoniously plugging them with newspaper and Polyfilla. No panic attacks for him, whereas nowadays I amincreasingly called out to pronounce upon hairline plaster cracks dramatised by white emulsion paint.

Expectations of building performance have become

unreasonably high. It is time for reactions to be tempered byconsidering the issues.

The great forces of nature are capable of breaking downmountains, so we must not assume that a mere building willlast indefinitely. Regular maintenance and occasionalstructural intervention are essential to slow the process of deterioration and to extend the life of a structure.Intervention may be aimed at conserving a buildingindefinitely, but a more realistic view may also be taken,with finite expectations for both original fabric and repairs(see Table 1).

What is structure?Those parts of the building fabric which confer significantstrength, stability and integrity. Roof carcassing, floors,walls, frameworks, and foundations form the principalstructural elements. Non-structural fabric such as plaster,render, windows and doors can also help stiffen a structure, but their contribution is not to be relied upon in a significantway.

What is structural movement?

Subsidence, heave, sway, bouncy floors, bulging walls,cracks, expansion and contraction are all forms of structural

movement. Such movement occurs all the time, and usuallyits magnitude is so small that it passes unnoticed. Only whenmovement threatens the use or safety of the structure need we be concerned.

■ Many specifiers exploited a loophole in the previousdrainage standard and designed systems to operate at75mm/hr. These systems worked perfectly well, butwere overwhelmed by higher rainfall events, which inthe south and east of England could occur every year or so. It should be stated that this was also a problem

with gravity drainage, but the link was not soobviously made. The new standard BS EN 12056-3:2000 closed this loophole, and so it is no longer anissue with siphonic drainage, but continues in somegravity systems.

What is happening today?

The current siphonic roof drainage industry is more maturethan the one that existed in the 1980s, with a wider spread of major companies. A draft British Standard, dealingspecifically with siphonic roof drainage, has been drawn up,and is about to go to the BSI committee procedure. This will

help define good practice in an industry that for so manyyears, in Britain, has been forced to set its own proceduresfor good practice.

In another step towards raising the industry profile, theSRDA was established. The association has the goal of 

 bringing together companies to promote good practice.Members of the association must show that they have:

■ a suitable outlet, pipework and hanging system; and ■ a functional computer-based flow-balancing program.

All these systems should have third-party accreditation.In addition to these requirements, member companies will beaudited by the association to determine, on randomly chosen

 projects, whether their design, installation and customer service meet the required standards.

With these stringent criteria for membership, anyspecifier using an SRDA member can be sure that they are

 placing this vital part of their project in the hands of acompany that has the expertise to do the job properly. ■

CemiCircular  WebWatch

For more information on the association, or siphonic roof

drainage in general, email info@siphonic.org or visitwww.siphonic.org

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Depending upon the financial, technical or material resources available, new structures or structural repairs may be designed to beserviceable for a specified minimum period. This might be:■ between cyclical inspections■ a loan repayment period■ full repairing and insuring lease duration■ 30 years (Housing Corporation rehabilitation cycle)■ 60 years (Housing Corporation new-build)■ 80–100 years (a lifetime – the layman’s expectation)■ ad infinitum  (Listed Buildings and Scheduled Monument)

Movement Fired clay brickwork Sand-lime brickwork Concrete brickwork Portland  

(mm/m length of wall) limestone  

Permanent moisture + 0.6 (expansion) – 0.25 (contraction) – 0.6 (contraction) Zero

contentReversible moisture ± 0.2 ± 0.3 ± 0.3 ± 0.1

movement

Reversible thermal ± 0.15 ± 0.3 ± 0.3 ± 0.1

movement

Note:

Values given are average. See BRE Digest 228.Values vary, depending upon exposure, restraint and pre-compression.

Movement is given for 30oC temperature range.

Portland stone is the ‘Rolls-Royce’ of masonry materials for dimensional stability.

Nature of movement Appropriate equipment Equipment accuracy

Level divergence Water level 2–5

Spirit level 2Dumpy level 1–2

Precise level (bar-coded staff) 0.2–0.4

Electrolevel 0.01 degree

Verticality divergence Giraffe 5

Plumb-line 2–5

Infra-red EDM (holographic prisms) 1–3Stains and cracks Tape extensometer 1–2

Perspex tell-tales 0.5

Vernier markers 0.1

Transducers (LVDT) 0.01

TABLE 3 Movement of monitoring equipment

TABLE 2 Thermal and moisture movement of masonry

TABLE 1 How long should buildings last?

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The seven causes of structural movement

 New structures are designed to carry their own weight and imposed loads so that strains are kept within reasonablelimits; safety factors are included to cater for variations inquality of materials, design and construction inaccuracies,and random/accidental forces. In historic structures,

detrimental movement results from inadequate design and construction, decay and ill-considered alterations.

1 Inadequate strength

Before the advent of calculus and the ‘modern’ engineer,early historic structures largely succeeded due to generationsof craftsmen constructing buildings in accordance with whatthey knew to have worked previously, and avoidingconstruction that had failed to perform. In other words,safety factors were incorporated by experience rather thancalculation. Nevertheless, in medieval timber structures it iscommon to find that secondary floor joists are often larger 

than they need be, while primary beams are undersize and sag excessively.

Apart from this, and some more singular problems, it is perhaps surprising that inadequate strength is generally notmore of a problem.

From the start of the Industrial Revolution, the increasinginvolvement of engineers, first with grand buildings and latterly more humble structures, ensured more adequatesizing of structural members. Exceptions include domestic

 buildings with timber floors overloaded by subsequent officeuse.

2 Lack of continuity or ‘togetherness’The vast majority of the nation’s structures are low-riseunframed buildings, where the individual components are

 predominantly held together by gravity and friction. Mostsuch structures (speculative Georgian and Victorian housing,for example) have outperformed the expectations of their constructors without the involvement of engineers and despite the ravages of two world wars. However, as

 buildings relax and become frail with age, the single kindestway of increasing their longevity is normally to tie themtogether. Conversely, the lack of continuity leaves thestructures vulnerable to disproportionate damage.

3 Material decay

Water is the principal agency affecting the decay of moststructural materials, causing:

■ frost damage of masonry■ rot of timber ■ rusting of iron and steel.

The battle can largely be won by giving a building a good roof and ensuring that driving rain is thrown clear of theexternal walls by generous drips, throatings, over-sailingcopings, and bonnets; and by controlling rising damp with adamp-proof course (dpc) or by ensuring that the ground is

well-drained, and the bottoms of walls are well ventilated.

4 Dimensional instability

Stone, brick and concrete expand and contract with changesin moisture content and/or temperature. The resultant strain

must be accommodated by the structure, or deformations and cracks will occur. If movement is cyclical, then such cracksmay grow due to the ‘ratchet’ effect of debris in the cracks

 preventing full closure.In most UK structures the principal loadbearing element

is masonry. Different types of masonry move at different

rates, and sometimes in opposing directions (see Table 2).This can give rise to differential movement and distortion.Fortunately most walls constructed before 1914 were set inlime mortar, which can accommodate considerable amountsof movement without cracking, due to creep (continual strainunder constant stress), whereas more modern walls set incement mortar require more frequent provision of movement

 joints. (See sketch 1.)

5 Subsoil and foundation inadequacies

Early medieval timber buildings had their main posts duginto the ground, but almost all buildings which still survive

had sill beams resting on low masonry plinths. Medievalmasonry buildings had walls which were built straight intothe ground without any attempt to disperse the load over a

 broad foundation; latterly the walls were sometimes stepped out or ‘corbelled’ to provide a wider distribution of the load on the soil, thus reducing settlement.

In good ground, corbelling continued until the first world war, latterly with a shallow strip of concrete first cast intothe trench, about 500mm below ground. In poor ground,short timber tiles were sometimes driven before commencingthe masonry. With the advent of modern mild steel and reinforced concrete around 1900, foundations became more

sophisticated.Movement of shallow spread foundations is commonlycaused by normal constructional settlement, mining, leakingdrains, shrinkable clay, tree-roots, changes of water-table,tunnelling and additional loads. (See sketch 2.) Flexiblehistoric buildings are often better able to cope withmovement than modern rigid structures, thanks to the

 prevalence of soft lime mortar, massive walls, timber frames,arches, and vaulted construction. Modern structures withslender walls set in hard cement mortar with brittle plaster and no cornices will show every crack. (Further reading – ref 4.)

6 Overall instability

A lack of bracing can ultimately lead to collapse. Many amedieval church, for example, has had a gable end rebuiltfollowing movement of its unbraced roof: this was prevented in more elaborate construction by diagonal wind-braceswhich were inserted in the plane of the rafters. In moderntimes, engineers learned this lesson again, when the 18mspan unbraced trussed rafter roof over the Rock FerrySchool gymnasium collapsed in 1976. Victorian shop-fronted terraces are also prone to leaning sideways, being

 perched on the slender columns. (Further reading – ref 5.)

7 Alterations and overloading Notched floor joists for services, doorways cut throughtrussed partitions, partly removed chimney breasts and overloaded floors are the most popular abuses of buildings.Many such alterations become obscured over the years, and 

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is structure

sound?

is use to

remain as

original?

re-user

OK

strengthen

structure

will

structure be

overstressed

eliminate

causes and

repair defects

no

yes

no

yes yes

no

Table 4 Sketch No 1: The evolution of wall construction and the

rising need for movement-joint

Sketch No 2: Partial underpinning

Ronan Point – the ultimate stage of structural

movement is collapse!

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it is only investigative work that will uncover the cause of the distortion. (See sketch 3.)

Acts of God and accidents are less predictable, except for domestic gas explosions, of which there are about 100 everyyear.

Explosions cause high pressures and suctions for very

short durations. These dynamic loads cause overload, stress-reversal and dynamic rebound of structural elements. Ductilematerials, such as steel and rc, perform better than brittlematerials such as timber, masonry and glass.

Modern framed buildings have good natural resistance toexplosions, particularly after 1970 when the BuildingRegulations were amended in the wake of the 1968

 progressive collapse of Ronan Point, to require better continuity of structures. (Further reading – ref. 3.) (See

 photo of Ronan Point.)

Assessment of stability

Against this background of potential causes of movement, itis hardly surprising that buildings seldom perform perfectly,and rarely acquire true stability. But is this important? If a

 building has sufficient commodity, firmness and delight, thenthe odd distortion can be part of the charm, particularly for ahistoric structure.

Although intervention by engineers may be unnecessaryfor the odd symptom of movement, the need for equilibriummust be borne firmly in mind when exercising the ‘100-year rule’. It is a powerful argument to say that if a structure hasstood for some years why should it not stand for another year, and subsequent increments to infinity?

Although nothing may have apparently changed duringthe period of observation, structural fabric graduallydegrades due to weather, thermal and moisture cycling, and dynamic loads. In so doing, structures can tiptoe towardsdisaster, and we must therefore be quite sure that a buildingwhich may only be showing signs of historic movement hasindeed acquired a new state of equilibrium and is not havingits margins of safety eroded perilously close to failure.

A stable structure is a system of pent-up forces. Forcenever sleeps and will take any opportunity to causemovement.

Structural movement is serious when the safety marginsof strength, stability or integrity have been significantly

eroded, or the movement is progressively leading to failurewithin a specified period. For a relatively modest structuresuch as a house, no action may be considered necessaryunless the structure is likely to fail within a period of 

 perhaps five years. For a cathedral, a much larger safetymargin would be necessary, of perhaps fifty years due to itsscale and the high cost involved in carrying out major works.

Expectations for the duration of a repair may also vary (see

Table 1).

An engineering assessment of the seriousness of any particular symptom of structural distress is not just bycalculation, but also through an understanding based on

 practical experience of the performance of structures and theintangible contribution of the non-structural fabric, such asthe stiffening effect of horsehair in old plaster, or modernsheet flooring.

The Building Research Establishment offers someguidance on the seriousness of crack widths, but this must be

used circumspectly.Cracks should be examined to determine their cause, not

rigidly filled in to see if they reappear, as this may restrictcyclical movement causing the problem to escalate. Carefulexamination can reveal the direction of movement, and whether movement is ongoing. (See sketch 4.)

In particular:■ Look at crack faces – how have they come apart?■ Are the arrises fresh and clean?■ Is there old paint or filler in the cracks?■ How old are the decorations?

If the probable cause of the structural movement is stillunclear or if the movement is suspected to be progressive,then movement monitoring may be warranted. (See Table 3.)Monitors are aids to diagnosis and prognosis, but are of nouse if sudden structural failure is likely.

Hopefully the days have long gone when well intentioned 

 but misguided builders stuck glass tell-tales across crackswith disfiguring blobs of resin, in the vain hope that their demise would explain the cause of the cracks. Mostly theglass would come unstuck, or schoolboys like me would  break the glass for fun. The arsenal of equipment availabletoday is vandal-resistant, and, when used wisely, givesmeaningful results. Once the causes have become clear, it isstraightforward to eliminate them, and also make repairs.(See flowchart, Table 4.)

Conclusions

Structural movement need not really be a problem whenconsidered rationally. Although structures rarely acquire truestability, cracks and bulges are not always serious, and crack monitoring is not automatically necessary. What needs tochange is people’s expectations.

The Victorians had the right idea; cornices to concealmovement between ceiling and wall junctions, woodwork  painted chocolate brown to camouflage joint shrinkage, and stretchy lincrusta wallpaper to obscure random cracks.

Further Reading

1 Richardson C (1985), ‘The AJ Guide to StructuralSurveys’ The Architects’ Journal: 26.6–24.7.

2 Richardson C (1988), ‘Distorted Walls – Survey,

assessment and repair’ The Architects’ Journal: 13.1.3 Richardson C (1993), ‘How to minimise bomb damage’

The Architects’ Journal: 30.6.4 Richardson C (1996), ‘Subsidence and Underpinning’

The Architects’ Journal: 22/29.2.5 Richardson C (1998), ‘Explaining the bookend effect’

The Architects’ Journal: 16.7.6 Gordon J E (1978), Structures, or why things don’t fall

down. Penguin Books Ltd, London.7 Appraisal of existing structures (1996) (2nd edn),

IStructE, October. ■

Contact details:Clive Richardson, Cameron Taylor, Bedford

Tel: 020 7262 7744email: clive.richardson@camerontaylor.co.uk

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Sketch No 3: Medieval box frame

Sketch No 4

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  C  E  M

  R  E  S  E A  R  C  H

Historic environments

and disabled access

 Historic places must do more to improve access for the

disabled to their sites and services in the light of UK disability legislation – but expensive alterations are not 

always needed. Gaye Pottinger , senior research officer, and 

 Henry Russell  , tutor in building conservation, at The

College of Estate Management in Reading discuss the

 findings of CEM research published in January 2005

(Estates Gazette , 29 January 2005, pp.68–69).

Castle battlements and dank dungeons are great fun toexplore, but they are not accessible to everyone. UK historicsites visited by millions of tourists every year were not builtwith disabled access as a consideration.

Social inclusion is now high on the policy agenda, and since October 2004 the Disability Discrimination Act 1995(DDA) has required reasonable building alterations toimprove access to services. But what is ‘reasonable’ and howare things changing for disabled tourists visiting historic

 places?Research presented earlier this month by the College of 

Estate Management shows that insufficient progress has beenmade in improving disabled access to historic sites and listed 

 buildings in the UK. This includes visitor attractions and guest accommodation where access to the tourism service isdependent upon access to buildings.

The study, sponsored by insurance company Marsh & Coand the Mercers Company, stresses that tourism businessescan and should do more to improve disabled access byfocusing on the visitor experience and adoptingorganisational and procedural changes first, beforeinstigating possibly expensive or unnecessary alterationworks. This is important, because the DDA is first and foremost about access to services, not buildings.

Small hotels and guesthouses appear particularlyunaware of the legislation and are slow to adjust. This could 

 be explained by the poor dissemination of information and guidance. But it is significant because 99% of the UK’s hoteland restaurant enterprises are small businesses (49

employees or less), and these businesses are not exemptfrom the DDA provisions on building adjustments.

Although the DDA allows some flexibility by requiring businesses to make only ‘reasonable’ adjustments,reasonableness depends on a number of factors, includingthe organisation’s size and resources. Small tourism

 businesses in particular have failed to undertake accessaudits to identify changes they could make relatively easilyand those they could defend as unreasonable. This failureleaves them open to action under the DDA.

Provision determined by the disabled

However, conducting an access audit, making servicechanges and altering buildings does not provide completecertainty nor a once-and-for-all solution to disabled access, because disabled customers will determine the adequacy of  provision. Also, it seems likely that acceptable standards willchange over time. The research therefore emphasises the

need to consult and involve the disabled and disabilitygroups in defining ‘reasonable access’. Businesses also need to keep their access arrangements under review.

The great historical significance of many UK touristdestinations also means that they deserve sympatheticmanagement and conservation, and keeping them ineconomic use is also crucial to their survival. Historicattractions generate an estimated £320m annually in ticketsales. Making historic places that are open to the publicequally accessible to the UK’s 8.5m disabled peopletherefore means that tourism businesses must find ways of  balancing the apparently conflicting requirements for accessand conservation.

This balance still favours conservation, in the face of uncertainties about what constitutes reasonable disabled access. Larger organisations operating from historic buildings – both hotels and visitor attractions – are waitingto see what the courts will decide when the legislation istested. Because the DDA lacks an enforcement agency,unlike other public interest legislation such as health and safety, enforcement action will come from aggrieved disabled individuals, possibly supported by the DisabilityRights Commission. Notwithstanding the DRC’s preferencefor reconciliation, service providers fear that the courts maytake a different view of reasonableness that could involve

them in considerable expense.Meanwhile, access solutions at historic places must be

treated on a site-by-site basis, reflecting their unique nature.This demands flexible attitudes on the part of service providers, planning authorities and disabled visitors. Anattractions manager interviewed for the research explained:‘Every property we have is different, so even if we’ve gotlisted building consent to do something at one property, wemight not get it at another. I think that’s difficult because itmeans that visitors might see something happening, such asthe installation of a lift, in one town rather than in another.’

Sometimes alternatives to full physical access at heritage

sites, such as audio-visual presentations and ‘virtual tours’,can be acceptable to disabled people. But a tendency toequate disabled access with wheelchair access may lead some smaller enterprises, such as guesthouses, to do nothing,or to cease operating rather than make access improvements.All businesses need to recognise that permanent wheelchair 

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users are a minority of disabled people, and much can bedone to improve access for all, including those with lessobvious mobility impairment, sight- and hearing-impaired,and people with learning difficulties. A great deal can beachieved through staff training and changed business

 practices to deliver improved customer care, before

contemplating building alterations.

Not enough trained advisers

Despite high-profile examples of successful access schemesin the historic environment (for example, the redesigned entrance of The Queen’s House, Greenwich, and the use of IT facilities at Shakespeare’s birthplace, Stratford-upon-Avon), it seems that there are not enough trained and experienced advisers to ensure high-quality solutions.

 Not all professionals appreciate either the range of needsor specific facilities appropriate for disabled visitors and how to balance these against conservation objectives. This

 presents a challenge and an opportunity for property professionals, a challenge that is also being addressed byeducation and training providers.

To sum up, progress with disabled access to heritagetourism has been slow and requires more attention byindividual service providers, supported by governmentinitiatives to disseminate information and promote current

 policy. Service providers that fail to respond run the risk notonly of court action but also the loss of business fromdisabled people who, with their friends and families, maychoose to visit places that are more accessible to them.

Raising the access stakes could ultimately be toeveryone’s benefit. One carer for a wheelchair user says: ‘Icould become disabled tomorrow – then what am I going todo when I want to visit certain places? I would go mad if Ihad to be stuck at home, not able to see places. It would bevery important to me.’■

Getting around historic buildings

The Disability Discrimination Act 1995 Part III came into

effect in October 2004 and requires reasonable adjustments

to buildings to facilitate disabled access.

The DDA definition of ‘disabled’ is wider than that used in, for

example, employment legislation. It is based on the medicalrather than the social model of disability. The social model

recognises the disabling nature of the environment, whether

organisational, social or physical, and looks for solutions by

altering that environment. The DDA is not a property statute

and therefore premises cannot be said to be DDA ‘compliant’

– it is the services that are offered to the public that must beaccessible.

Under the spirit of the DDA, disabled visitors to historic sites

should be offered the same level of access as other

members of the public, and need not be admitted on those

occasions when public access is restricted in the interests of

conservation.There is no small business exemption under the DDA, which

also applies equally to services that are free as to those that

must be paid for.

CemiCircular WebWatch

The full research report ‘Historic environments and tourism:

improving access for disabled people’ is available free from

the College of Estate Management website www.cem.ac.uk.

Hard copies can be purchased from CEM Publications.

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Book – Historic buildings

measured surveys

 A new book, Measured Survey and Building Recording for 

 Historic Buildings and Structures, editor Ross Dallas and  published by Historic Scotland  (2003 ISBN 1-903570-92-1)is reviewed by Henry Russell  , Tutor in Building

Conservation at the College.

Historic Scotland has an exemplary record in publishing books and guidance for the practitioner, and this guide is oneof that series. Their publications are intended for Scotland 

 but deserve wider readership. The editor, Ross Dallas, is achartered surveyor, who has contributed to the College’sConservation of the Historic Environment Programme aswell as to the RICS Building Conservation Journal. This is aworking handbook and is probably best used as a referencework. It is packed with detail and as such is not an easy read.

Dallas starts by stating the aim of the book, which is todescribe the survey tools and methods for recording historicsites, as a means of gaining a better understanding of them.In the historic environment it is axiomatic that a building or site must be fully understood before any changes areimplemented. A detailed survey and record of a building is

 just one of the ways of doing that. The process is known asconservation-based recording and analysis – CoBRA (seeKate Clark (2001) Informed Conservation, EnglishHeritage).

The survey techniques described are those that have

wider application to building and land surveyors. In thehistoric environment they are being taken up and used byarchaeologists too, and many of the contributors to this book are archaeologists. In recent years, the skills of archaeologyhave been lifted from the ground, turned 90 degrees and applied to buildings.

The use of standard plans elevations and isometrics of  buildings are discussed. The old Royal Commission on theHistorical Monuments’ Recording historic buildings: adescriptive specification (1996) RCHME, Swindon,currently being revised) is a good guide for recommended drawing conventions. Probably most interesting to surveyors

will be the chapter on survey techniques, and the advantagesand disadvantages of each. These fall into three maincategories: hand survey (tapes and levels), instrument survey(theodolite and laser scanning), and photographic survey(rectified photography, stereo photogrammetry and orthophotography).

Hand survey has its uses with small buildings and smallareas of detail, such as traceried windows. It has theadvantage that, through close inspection and measurement,the surveyor gains a detailed understanding of the structure.Instrument survey is good for rapid survey to produce a lowlevel of data. Total station theodolites now use reflectorless

technology, so inaccessible points can be plotted. Laser scanning has the possibility of both rapid survey and highlevel of detail, because a scan is able to capture a wholeseries of points – known as a ‘point cloud’. It is still indevelopment, as special computer programmes are needed toread the massive amount of data generated, but has theadvantage of generating 3D modelling.

Of particular application to historic buildings – and toarchaeology – are the photographic survey methods.Rectified photography and photogrammetry are used wherethe irregular detail on elevations needs to be detailed. Theyare good at producing stone-by-stone records of buildings

for archaeological analysis. Rectified photography usesstandard medium- or large-format cameras. The images arethen enlarged to scale. Photogrammetry combines

 photography with CAD, using a stereo viewer to extractsurvey information from photographs using specialistcameras. It is not a cheap option but produces high qualityresults.

There are other methods which do not fall readily intothese categories, such as radar surveying techniques, usefulin locating hidden features such as chimney flues. Casestudies illustrate the use of the techniques described.

The problem with any assessment of particular tools isthat they will soon be superseded as technology advances,

 but this book very usefully details the survey methodsavailable with their advantages and disadvantage. It is verywell illustrated, but use it as a reference work, not atextbook. ■

CemiCircular WebWatch

Dallas R (Ed) (2004) Measured Survey and Building 

Recording for Historic Buildings and Structures can be

obtained from Historic Scotland (£22.50). The book

comprises 9 chapters, 180 pages and 184 illustrations. For

more details go to: http://www.historic-scotland.gov.uk/ product_detail.htm?productid=639

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Construction

Defined provisional sums

What is the difference between a ‘defined provisional sum’

in the JCT98 contracts and an ‘undefined’ one?  Ann

 Minogue , partner with solicitors Linklaters, explains that it 

has nothing to do with price certainty (Building , 3

 December 2004, p.49).

As a novice to building contracts I was baffled by the jargon used in them. For example, I had no idea what wasmeant by the term ‘provisional sum’. It soon becameobvious that it was synonymous with ‘black hole’. The sumwas no more than a figure inserted by the professional team.

If the work covered by it was to be carried out, aninstruction had to be issued; that instruction was then valued as a variation; and extensions of time and loss and expenseclaims could then follow.

So what is the point of provisional sums? Presumably itis to forestall criticism about increases in the contract sum.Does the employer ever understand that the contract sumand the date for completion include these black holes? Theanswer in my experience is almost always no.

Still more mysterious jargon has since been included inthe JCT standard form in relation to provisional sums.JCT98 includes a distinction between a ‘defined’ provisionalsum and an ‘undefined’ one. Probably only quantitysurveyors expert in the standard method of measurement canexplain the difference exactly, but the distinction seems to bethat, for defined work, there is enough information in thecontract to enable the contractor to price preliminary items,to allow for the work in its programme and to assess itsimpact on other work. But if that is the case, then surely it isalso possible to price the work itself?

Take the example of a reception desk – an itemcommonly covered by a provisional sum. The argument is – I think – that the contractor can anticipate the preliminariesand programme issues arising from the supply and installation of a reception desk even though it does not know

the precise details of the desk to be supplied. So a defined  provisional sum is inserted.

But surely if the contractor does not know, for example,whether the reception desk is to be made from some scarce

granite with long delivery times, or alternatively glass whichmight be available immediately, it cannot accurately assessthe preliminaries and programme implications of its supplyand installation?

Accordingly, the mystery of the defined provisional sumunravels and the architect is back where it started – it mustnot only value the reception desk itself as a variation, it mustalso look at the effects it has on other work, adjust the preliminary items – and it may have to give an extension of time and, potentially, allow for loss and expense.

It must also be remembered that this concept of thedefined provisional sum appears only in the JCT standard 

form 1998 edition. It does not appear in JCT WithContractor’s Design. Again, why is this? It is presumably because the employer’s requirements document, which isincorporated in this form when it is signed, is the limit of thedesign to be carried out by the employer’s professional team.

Any ‘gaps’ in that design are to be filled by thecontractor’s proposals, and produced by the contractor either  before the contract is entered into or in detailed designinformation afterwards. In other words, if work is not properly defined in the employer’s requirements, it is for thecontractor to define in whatever way it chooses. It candecide whether the reception desk is granite or glass, and if the employer objects and wants to secure a higher quality product, it must issue a change order anyway.

All of which means that the distinction between a defined  provisional sum and parts of the works that the employer’srequirements simply does not define in detail is meaningless.

And what should the professional team tell their clientabout the distinction? They should confess that it is adistinction without real meaning unless and until the designfor the reception desk is agreed. No employer should be led to believe that it is possible to buy any certainty if thecontractor does not have enough design information to pricethe works.■

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Managing risk

 It’s better to face up to construction risks than ignore them,

says Tony Bingham , barrister and arbitrator. The question

is, do you take the umbrella approach or the mushroomapproach, or one of the other four ways to manage risk?

(Building , 27 August 2004, pp.48–49)

Heaven knows your construction work is heaving, bubblingover with risk. There is a real chance that the job will makea loss, that you will get the blame, that the firm will go bust.In fact, there is so much risk that it is best not to think aboutit.

 No, no. Stop turning a blind eye to ‘bloody risks’. Turnthat idea on its head … lick risk by looking it in the eye,then managing it to make it more likely not to happen. This

is where a University of Reading report, commissioned bythe RICS, comes in handy. It’s called The Management of 

 Risk – Yours, Mine and Ours. Now the RICS must be fed up with being kicked in the

groin; time for a pat on the back. And if this RICS presidentfella Barry Gilbertson really does want to get his members

 back to ‘a sense of belonging’, do something really useful,old chap. Take that theme in your report and help everyRICS builder, QS, manager, measurer, valuer to get good at‘making it more likely that good things will happen’. And doit within their membership fee. In other words, for free.

The RICS report says risks are inherent in allconstruction projects. Yes, yes, they can be transferred,accepted, managed, minimised or shared but they must not

 be ignored. The traditional way of insulating yourself fromrisk is to treat it as another four-letter word and pass the

 price to the consumer. Another tradition, says the RICS, is to play off the subcontractors against each other to gain thecheapest price. The report says, ‘taking on a risk at bid stagein the hope of passing it on to somebody else is folly intoday’s business environment’.

Apparently there are five ways to tackle risk (I think there are six):

■ The umbrella approach: where you add a large risk  premium to the price.

■ The ostrich approach: where you assume thatsomehow you will muddle through.

■ The intuitive approach: that says don’t trust all therisk analyses, trust your intuition and gut feeling.

■ The brute force approach: that focuses on theuncontrollable risk and says we can force things to becontrolled – which of course you cannot.

■ The snowboard approach: that says you are on asnowboard on the downhill run, you have pre-planned and analysed where the pitfalls are and you havetaken corrective action. Some things can becontrolled, others cannot. For example, speed and route can be controlled, the weather and the

competition cannot. Focus on the actions needed tomanage the risks throughout the run, arrive safely and win through.

And the sixth? Every QS will tell you that theconstruction industry uses the mushroom approach: keepeveryone in the dark, then chop their legs from under themwhen nobody is looking.

Six ways to handle risk

 Now let’s get down to it. Risk is the combination of the probability of an event and its consequence. If we can

fathom these two and have a mindset of making it morelikely that good things will happen, this will be fun. So, whatis probable? First, at building concept stage, it is probablethat the budget set by the client will be insufficient for thelevel of quality and performance expected from the project.Then at design stage it is probable that the design team willfail to design within budget and by then the job is under way.Also, it is probable that there will be lack of design co-ordination among the design consultants and little respect for design management. Then, at construction stage, it is

 probable that there will be changes in design and requirements, and in consequence programme delays and disruption. And, all that will lead to disputes.

So, having fathomed the probability of events and fathomed the consequences, how can we ‘make it morelikely that good things will happen’? Easy, really. The good thing is that you will have a whopping catalogue of disputesand this will bring a smile to the face of all us adjudicators,arbitrators and dispute sorter-outers, and, of course, theRICS. Last year it made about 10,000 arbitral-typeappointments at £300 a go. So, come on – keep making itmore likely that good things will happen … ■

CemiCircular WebWatch

The report referred to, ‘The management of risk: Yours, mineand ours’, commissioned by the RICS Project ManagementFaculty from the University of Reading, can be found at the

RICS members website at this link: www.rics.org/ 

Management/Projectmanagement.

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. Settling claims

When it comes to settling a claim under a building contract,

drawing up the final agreement yourself without the aid of 

an expensive lawyer might appear simple and attractive, but 

beware – there is rather more to it than agreeing the figure. Melinda Parisotti , in-house barrister at Wren Managers,

explains how to make sure the agreement means what it says

(Building , 8 October 2004, p.53).

DIY claims handling is only for the stout of heart. Nevertheless, many claimants and defendants alike will wingit alone without legal assistance, regardless of the undeniablerisks. Reaching an agreement without legal guidance is onething. Drawing up a settlement agreement – one that doeswhat you think it does – is quite another.

Looking at this principally from the payer’s perspective,

I have set out below some of the many pitfalls just lying inwait, should you venture into the hazardous world of settlement agreements without a trusty legal hand to grasp.

First of all, check that person with whom you are dealinghas the authority to negotiate and sign the settlementagreement, so that it will be binding on their organisation.

Hopefully the main players will come to mind whendrafting your settlement agreement, but there may be other 

 parties, including associated companies, who should benamed as part of the deal, even if they are not making any, or any significant, contribution in monetary terms. Otherwise,they might come knocking on your door the next day inrespect of the very matter you thought you had justdispensed with. And, of course, even if named, there maystill be issues as to whether the deal is legally binding onthird parties.

On a related point, you may, as the payer, require anindemnity from the payee in respect of any claims third 

 parties might bring against you.If you ask somebody who has just come out of a

settlement meeting if they know exactly what figure theyhave settled at, you might expect an indignant retort. Butinquire whether their figure has addressed the questions of legal and expert costs, VAT, interest and the like, and theymay start looking a little sheepish. The settlement agreement

should clarify whether these matters have been included. If not, it should specify how they are to be dealt with.

Insurers simply do not take kindly to surprises. If you arerelying on them to cough up the readies, you need to be surethey are going along with the deal. And bear in mind youwill still be on the hook for any excess. Can you produce it by the agreed date?

You need to specify the date of payment in the agreement

or you can be certain that the claimant will be snapping their fingers for their money before the ink on your settlementagreement is dry. Again, if you need to pay by instalments,that must be stated in the agreement.

Is foreign currency involved? Bear in mind the extra timeand costs involved in the transfer. You may also wish toagree a set exchange rate so that a major fluctuation in therate between settlement and payment does not catch you out.

I covered the question of full and final settlement in a previous article ( Building, 20 September 2002, page 57).Depending which side of the fence you are on, you may wishthe settlement to be full and final, or you may prefer to leave

the door open for future claims. Obviously it is in the payer’sinterests that the settlement agreement should stem all futureclaims, even if unrelated to the matter in hand, but that israrely the intention of the claimant. However, somewhat lessrarely, this draconian interpretation is the unintentional effectof sloppy settlement wording.

Is confidentiality an issue? If so, say so. It might also beworth agreeing with the other side how to field any queriesarising from third parties [also see item on ‘Confidentialityand legal privilege’ in the Law section of this

CEMicircular ].If a claim is made against you as a consultant or 

contractor, you may intend that your fees for the job be

wrapped up in the settlement figure. Either way, you need toclarify.

As far as admitting liability is concerned – don’t! The payee has your money, so he does not need your grovellingadmission at this stage, and it could have all kinds of adverserepercussions – not least the triggering of independentclaims.

If you still manage to make a dog’s dinner of your settlement agreement, at least be sure it clarifies which lawand jurisdiction apply. You will need to know this when youspend the next two unhappy years tied up in litigation over its interpretation.■

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Causation

 Did the building of the London Underground Jubilee Line

cause the pipe to burst, or would it have happened anyway?

Susan Lindsey , barrister at Crown Office Chambers,

discusses how the ‘but for’ test can be used to exclude thingsthat are not a cause, but is still not a reliable test of 

causation (Architects Journal , 11 November 2004, p.48).

For 75 years the 36-inch cast-iron water main under StThomas Street, Southwark, served its function, taking in itsstride the vicissitudes of life (Thames Water v London

 Regional Transport ; judgment 18 August 2004). Then, between 1995 and 1997, London Underground built the newJubilee Line nearby. On 24 October 1999 the pipe suddenlyfailed, giving rise to claims that amounted to many millionsof pounds.

Thames Water blamed London Underground (LU),alleging it had compromised the ground support for themain, causing damage to the pipe. LU opposed the claim,saying the pipe was so loaded already by historic stressesand strains that its actions were simply the straw that brokethe camel’s back. That, it said, was not sufficient to give riseto a legal liability.

Similar arguments might arise in the context of a buildingcontract to carry out works to an existing building. For example, unbeknown to a contractor, previous works mayhave seriously compromised the structure. As soon as the

 builder starts work, damage results, triggered by the newwork. Other issues arise, including what the contractor isobliged to do and what it should and could have noticed 

 before starting work. But how does a court approachquestions of causation of damage in such cases?

In Thames Water , HHJ Wilcox took the well-knownstarting point of what is called the ‘but for’ test. At first sightthis appears a useful and straightforward test. If ‘but for’ thedefendant’s actions the damage would not have occurred,then the defendant is liable. But the test runs into problems,

 particularly when there is more than one possible cause of damage.

The judge referred, among other authorities, to Lord Hoffman’s speech in Banque Bruxelles Lambert v Eagle

Star , the well-known case about the extent of damages payable by a valuer who negligently over-values propertythat turns out to be inadequate security, in part because of a

fall in the property value. Lord Hoffman gave theilluminating example of a mountaineer who, before settingout on a difficult climb, asks a doctor whether his knee is fitenough for him to undertake the journey. The doctor has aquick look and declares the knee is fine. The mountaineer sets off, but suffers an injury that is unrelated to his knee but

is a foreseeable result of mountaineering. ‘But for’ thedoctor’s advice, the mountaineer would have stayed at home,suggesting the doctor is liable. But common sense says thatis wrong. There is no sufficient causal connection betweenthe doctor’s advice and the loss suffered by the mountaineer.

So the ‘but for’ test is a filter that can exclude things thatare not a cause and identify things that are a potential cause,

 but it cannot be a reliable test of causation. Instead, the courthas to decide on a common-sense basis what caused loss,and within the context of what it was that the parties weresupposed to be doing.

In applying this common-sense approach to the facts of 

Thames Water, the judge had to consider extensive evidenceabout the underground conditions, both in geological termsand in terms of man-made events that had altered the ground over time. He also heard about the condition of the pipe and the stresses and strains it had been subjected to, including asa result of London Underground’s works. The documentsreferred to ranged from post-war bomb-damage maps, back through 18th century maps showing street realignment, toarchaeological records of Roman and mediaeval activity.The judge had the benefit of expert evidence on thesignificance of all this data in relation to the pipe failure, aswell as expert assistance from metallurgy experts about thefracture damage to the pipe.

Applying a common-sense approach to this wealth of technical data, the judge concluded that LU’s work caused differential settlement in the made ground around the pipe,triggering localised movement in the alluvium beneath thefailed piece of pipe, thereby overloading the pipe joint.

Had the settlement caused by LU not happened, the pipewould have continued in use for many more years. HenceLU had caused the damage, and was liable. ■

CemiCircular WebWatch

The website of Crown Office Chambers –

www.crownofficechambers.com – offers a good selection ofarticles and case notes covering current construction law

issues.

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Corporate social responsibility

The UK construction industry still has a poor record for 

work-related deaths. Following the announcement of a

 proposed corporate manslaughter bill in November 2004, a

survey by consultants KPMG showed corporate socialresponsibility rising up companies’ agendas. Angela

 Monaghan reports on the survey findings (Building , 3

 December 2004, p.20).

Corporate social responsibility, or CSR, was pushed up thegovernment’s agenda at the end of November 2004, when adraft corporate manslaughter bill was unveiled in theQueen’s speech. The proposals are far-reaching, withnegligent company directors facing imprisonment or fines on

 personal wealth when a member of staff is killed in theworkplace.

The stakes have been raised, and the building industry asa whole is finally waking up to the fact that it has to takeCSR seriously in order to be ahead of the game. A survey

 published by consultants KPMG last week showed that CSR is catching the attention of more companies, and is creepingup the industry agenda – albeit slowly.

KPMG interviewed 226 industry people, 98 of whomwere from quoted companies. The survey showed that almost70% believe that CSR has a large commercial impact on

 business, compared with about 50% last year.However, at a time when construction-related deaths are

still hitting the headlines, and as companies struggle toattract the levels of staff they need, the survey shows that theimportance of having sound CSR policies is still not fullyunderstood. The issues involved are wide-ranging and include health and safety, environmental and pollutioncontrol, community development, social accountability,ethics and integrity and stakeholder engagement.

Thirty-four per cent of those questioned said businesswas affected by public opinion of CSR , but this represented only a 10% increase on the 2003 figure, and mostrespondents still said that public opinion had no effect. Thisseems all the more strange at a time when staff shortages areone of the industry’s major concerns. Younger people areincreasingly concerned with the overall ethos and values of 

the company they choose to work for – demonstrated by thefact that the CSR section on company websites receives the

greatest number of hits from graduates and  potential employees.

More than half (51%) of those questioned said thatclients were sending out questionnaires at the pre-qualification stage of a tender. Just 28% were asked toengage in detailed discussions on CSR, but this figure was

still more than the 11% recorded last year and will no doubtcontinue to rise.

The responses also indicate that most investors and shareholders do not raise the issue, although, again, the pastyear has seen an increase in those who do, from 17% to45%.

A panel of eight industry executives invited by KPMG todiscuss the survey said that addressing CSR issues would  become more common as clients drove it up the agenda.Public sector and blue-chip clients are most concerned withCSR policy, said the panel, partly because those clients arethe ones that tend to have a policy in place within their own

organisation.Richard Whittington, head of building and constructionat KPMG, said: ‘Our survey shows that the industry ismoving slowly towards embracing the CSR agenda. The risk to businesses’ reputation of not actively engaging with theCSR agenda can be huge. Our survey demonstrates that theseissues are now beginning to be addressed and debated throughout the sector.’

One surprising statistic revealed in the survey was thelack of concern and awareness among people in financialroles about the new non-financial reporting regulations to beimposed on UK quoted companies in four months’ time.

The operating and financial review (OFR) will require

companies to report on staff, environmental, social and community issues, so that they are more transparent abouttheir strategies. Yet, despite the imminent changes, 61% of those in finance roles questioned by KPMG said that theydid not anticipate including CSR issues in their OFR disclosure. And this is despite the fact that, for quoted companies, a bad reputation in the public domain can have adirect and negative impact on a share price – a problem towhich Jarvis has fallen victim.

CSR is clearly keeping more directors awake at nightthan this time last year, but it would seem that more than lip-service has to be paid if the industry is to attract new

talent. ■

R  E  S  E  A  R  C  H  

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The Millau Viaduct, France

Foster and Partners’ Viaduc de Millau in southern France is

the highest and longest cable-stayed bridge in the world, at 

nearly 2.5km, carrying the A75 motorway across the Tarn

Valley. It was opened in December 2004 by President Chirac and promises not only to alleviate a traffic

bottleneck but also to become a tourist attraction in its own

right for the scale and elegance of its construction. Thomas

 Lane describes the feat of construction, talks to the engineer 

and meets some enthusiastic locals (Building , 24 September 

2004, pp.46–52).

C’est magnifique!

For three years, frustrated motorists using the A75 motorwayin France have been tantalised by progress on Europe’slargest civil engineering project. The drive from Béziers in

the south starts out well enough, as you hurtle northwardsthrough mountain scenery. Frustration sets in 19km south of Millau, as the motorway empties its traffic on to theequivalent of an A-road and you slow to a grinding crawl – itcan take up to three hours to get through the town and back on to the A75 north of town. Eventually, however, the road dips and rounds a corner to reveal a vast panorama: a huge2.5km wide valley slices deep between two elevated 

 plateaux and a nearly completed motorway viaduct stridesacross the void.

This structure rouses a host of emotions. The first isamazement at the sheer arrogance of trying to bridge such agap. But then you marvel at the brilliance and scale of theengineering. You also wonder how on earth permission wasgranted and how the contractors kept off protesters in one of the most beautiful parts of France. The ‘how did they getaway with it’ feeling is tempered by the extraordinaryelegance of what is after all a motorway bridge – this makesmore sense once you realise architect Foster and Partnerswas involved in its design.

Finally there is the anticipation in knowing that next year there won’t be infuriating traffic jams to plough through butthe chance to fly across the valley on the Viaduc de Millauand on to Clermont-Ferrand.

Above all else, however, rises one question: how did they

do it?The Viaduc de Millau’s vital statistics read like an entry

in a book of records. It is the world’s longest multi-pier cable-stayed bridge, at just 40m short of 2.5km, and thehighest at 343m. Seven piers step delicately across the valleyover the River Tarn to support the deck. These are not theusual Mr Blobby style motorway piers but are hexagonal in

 plan and curve gently towards their apex from the base. Each pier splits in two like a tuning fork 90m short of the deck tomake the structure appear even more refined.

These piers are the highest in the world. To put this in perspective, if the Eiffel Tower was sitting in the River Tarn

it would barely protrude above the deck. Pylons rise 90mabove the deck, elegantly mirroring the forked design.Cables fan out from the pylons to transfer loads from thedeck down into the piers.

It has taken many years to get to this stage. A range of options were explored between 1987 and 1989, according to

Michel Virlogeux, who at the time was the head of bridgeengineering at the government-run major roads division, theService d’Etudes Techniques des Routes et Autoroutes.Suspension bridges in two different locations were rejected  because of local opposition and unsuitable ground, and a bridge combined with a tunnel was rejected because of its

complexity. ‘We were practically in front of a wall,’ saysVirlogeux. ‘The director of road engineering said it is not possible to span one plateau to the other because of thelength of the span and for aesthetic reasons.’ This gotVirlogeux thinking. ‘At this time I had the idea of the cable-stayed bridge.’

This idea was adopted and eventually culminated in acompetition in 1994 to select a winning design. Thegovernment realised it had to go to exceptional lengths towin the public over to the idea. ‘A project from theadministration would not have been accepted,’ saysVirlogeux. ‘Everything that comes from the administration is

to be fought against. The best way was to have acompetition, as the public accepts the decision of a jury.’The second strand to the strategy of winning over public

opinion was to make the viaduct more visually acceptable byinsisting an architect be on each team. ‘It was unusual thatthe project stipulated that all the competing teams had tohave an architect in the team,’ says Norman Foster.

Foster says his design differed from the other entries inone important respect. ‘They had let a competition for a bridge over the River Tarn,’ he explains. ‘Every entry had made a response that focused on this very small river. Thesewere large-span structures with symbolic arches over theriver. My point was that this was not a competition for a

 bridge over the River Tarn. We have not done a bridge over the River Tarn but the most economical crossing betweentwo plateaux that also happens to cross the River Tarn. In away we have taken a divergent, philosophical line. Thehighest part of the columns just happened to be where thistiny dribble of a river is.’

The architect and engineers worked closely together onrefining the design once the result of the competition wasannounced in 1996. The bridge is in many ways a perfectsynthesis between architecture and engineering as aestheticconsiderations combined successfully with engineeringdemands. An example is the forked piers. This bridge relies

on very stiff piers and pylons combined with a flexible deck.The piers need to be very wide so they don’t bend towardsan asymmetric load on the deck. But because the bridge is2.5km long, thermal expansion up to 600mm is possible ateither end. Because this movement is incompatible with thetwo wide piers at each end of the deck, the solution is todivide them into two so they can provide the necessarystiffness yet accommodate thermal movement.

Foster has turned this into an aesthetic virtue. All the piers share the same forked design as it lightens their appearance, and much effort has gone into shaping the piersto make them as elegant as possible. They are multifaceted 

for added visual interest and also incorporate grooves thatcast shadow lines that vary in width according to the time of day. The piers are also arranged on a slight curve, giving the bridge a radius of 20km. This is intended to add to the visualimpact of driving across, as motorists can see the bridgeunfolding before them.

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Virlogeux says that when engineering demands mademeeting aesthetic requirements difficult, Foster was veryaccommodating. Originally Foster wanted a triangular-shaped deck in section but tests showed that this wouldn’twork. ‘We put it in a wind tunnel and it was a disaster,’ saysVirlogeux. He says the deck behaved in a similar way to thedeck on the Tacoma Narrows Bridge in Washington state,USA, which in 1940 started swaying and ultimatelycollapsed in high winds.

Virlogeux wanted to use a trapezoidal deck that he had 

 previously used on the cable-stayed Pont de Normandie. Hesays the architect could have insisted on the triangular deck,as the politicians had stipulated that nothing could bechanged without the architect’s agreement. ‘I met with Foster and explained that we had the same problem as Tacoma. Hesaid “no problem” and changed the design in ten minutesand we went back to a trapezoidal shape.’

All the effort put into finely honing an aesthetically pleasing solution has paid off, as there have been virtually no protests either before or during construction. The A75 cutsthrough the traditionally isolated and poor region of theMassif Central, and was intended to open the area up.

Virlogeux says people were very much in favour of themotorway because it was hoped it would bring economic benefits and halt rural depopulation. Also, Millau residentswere sick and tired of the traffic jams that made getting intoand around the town a nightmare. ‘The population was veryupset by the delays to the project – which doesn’t usuallyhappen,’ Virlogeux explains. ‘We have exactly the oppositesituation in the French Alps where a proposed motorway has

 been completely blocked.’Indeed, the construction of the Viaduc de Millau has

 become something of a celebratory experience for France.Eiffage, the contractor for the viaduct, built a visitor centreunder the emerging structure and says 400,000 people have

visited since work begun. The town has helpfully signposted several vantage points where the viaduct can be more fullyappreciated and these are populated by hordes of snappersarmed with digital cameras.

For the A75 motorist the bridge could not open soon

enough and Eiffage kindly obliged by bringing the scheduled completion date of 10 January 2005 forward to the week 

 before Christmas. President Chirac snipped the ribbon tospare motorists seasonal gridlock and the chance toexperience a new, tantalising view of Millau that, traffic

 permitting, will last just three minutes.

What the locals think of the viaduct

Viviane de Sousa, camp site owner

Although the traffic jams will go, people are worried that

businesses will go, too.