I

Cracking and Building Movement

by

Peter R. Dickinson FRIes, FCI Arb

chapter on MOllitorillg by

Nigel Thornton BSc (Hons), C Eng, ~IICE, MI HT, FGS

129057

111111111

•

, ..... '\ RICS \~ BOOKS

Contents

Preface

WHY HAS CRACKING BECOME IMPORTANT?

Introduction Why is cracking now so prevalent?

Insurance Climate change Changes in industrial and building materials Professional Indemnity Insurance

2 WHY BUILDINGS MOVE - AN OVERVIEW

Introduction Building movement which results from conditions below ground

Settlement of foundations Subsidence of foundat ions Undermining of founda t ions Consolidation of fill below foundations or floors Chemical attack

Building movement which results from conditions above ground The use of'green' materials Central heating Movement due to inadequate design Faulty construction, alteration and/or repair Overloading and over stressing Chemical reaction Material deterioration -Iemperature changes Natural drying of the structure and finishes

3 TYPES OF MOVEMENT

Expansion and shrinkage Clay brickwork Concrete block work Calcium silicate Natural stone Reinforced concrete Mass concrete and render Timber

Moisture/thermal movement Moisture/thermal movement of day bricks Moisture/thermal movement in concrete blockwork Moisture/thermal movement in calcium silicate bricks

1 1 2 2

3 5 5 5 6 6 6 7 7 7 7 7 8 8 8 8 8

II II II II II II II II II 12 13 13

iii

Cmc/,;itrji dlld Iluildill}; MovE'mnrl

Moisture/thermal movement in concrete and render 18 l-o loisture movement in mortars 19 l-oloisture/thcrmal movement in timber 19 Moi!>ture/thermal movement in roofs 19

4 CHANGES DUE TO CHEMICAL ACTION

Sulphate altack 23 Rendering 24 Ground-bearing slabs 24 Foundations 25

Corrosion 25 In cavity walls 25

Carbonation 25 Alkali-silicate reaction 25

5 STRUCTURAL MOVEMENT - A DETAILED STUDY

Settlement 27 Foundation subsidence 27

Shrinkage of day subsoils 27 Clay heave 30 Foundation undermining 32

Mining operations 32 Leaking drains or the presence of land drains 32

6 THE EFFECTS OF MOISTURE AND TREES

The effect of moisture on day subsoils 35 The Clay Plasticity Index 36

The effecl of trees on day subsoils 36 How trees damage buildings 36 Methods of tree risk assessment 37 Worked example 40

7 CONTRACT UAL MATTERS

'laking enquiries 45 Creating the Contract 45

The Contract 45 The Offer 45 The Acceptance 45 The Performance is carried out by both parties 45 The Terms of the Contract 46

The Contract in writing 46 Standard Terms and Conditions 46 The Misrepresetltatioll Act 1967 46 The Unfair Cotltract Terms Act 1977 46 The Unfair Terms ill Consumer Collfracts Regulations 1999 47

The practice of creating a Contract 47 The Building Contract 47

What to do about specialists! 48 '10 whom can the specialist be made responsible? 48

The Constructioll (Design and Management) Regula/ions 1994 48 Party Wall etc. Act 1996 49 Housillg Grallts, COllstrtlctioll a1ld Regeneratio1l Act 1996 50

'"

8 INSPECTION AND RECORDI NG DEFECTS

Symptoms Gathering the information The site inspection

Inspection of the property Start where the crack has been identified Record the general site characteristics Sketching and measurement of cracks

Basis for development of an inspection record Further investigations

Determine the age of the crack Recording variations in level Recording movement in leaning walls The acceptable degree of tilt Drain te:.l:. Identification of the soil type and the type of tree

9 ASSESSI NG THE DAMAG E

Introduction Assessing the damage

What is the cause of the damage? Is it likely 10 get worse? If so how quickly? Landslip risk Failing retaining walls Leaking drains

Recognit ion and assessment of heave damage Recognition and assessment of subsidence movement

Indicators of subsidence Assessment of cracking Repairing the damage What if foundation movement is the cause? What if tree roots are decided to be the cause of the damage?

Solutions to tree root problems Assessment of cracking and corrosion in concrete

Corrosion of reinforcement High Alumina Cement (HAC)

Crackillg and Buildiug Movelllelll

51 51 52 52 53 55 55 57 58 59 59 60 60 60 62

Recognition and assessment of non-subsidence, non-heave structural movement

65 66 66 66 67 67 67 67 68 68 68 68 69 70 711 71 72 73 73

10 MONITORI NG OF CRACK AN D MOVEMENT DAMAGE

Requirement for and frequency of monitoring Positioning of crack monitoring devices Methods of crack monitoring

The two dot method Glass tell tales Plastic sliding plates The three screws method Presentation of results and interpretation of data Two screw method

Level monitoring Precise levelling equipment

Sample calculations

77 77 77 77 78 78 78 80 80 80 81 84

11 THE REPORT

The front cover An index First page Technical investigation Assumptions made Conclusions and recommendations Signature Appcndice:, Copies Layout of the report

12 HISTORY OF BUILDING AND REPAIRS

An overview Kc)' evenlS and legislation

Typical 'period' defects which might be expected

13 SPECIFICATIONS AND SCHEDULES

Specifications Schedules of Condition or Dilapidations

Schedules of Condition Schedules of Dilapidation

14 SPECIFYING THE REPAIRS

Chemical reactions Corrosion Sulphate attack Alkali-silicate reaction

j\laio substructure repairs Typical underpinning specifications Typical underpinning specification clauses

Superstructure repairs and typical specifications Repoinling Repair of damaged brickwork - to rebuild or nOllO rebuild? Floor repairs - solid floors Floor repairs - timber floor~ Thermal cracking Roof spread

Listed buildings and heritage issues Questions to ask when designing extension foundations

15 SUPERVISION OF BUILDING WORKS

Site inspection I nslruction book Dealing with site personnel Supervision of building works - checklists

,i

89 89 90 9Q 91 91 91 91 91 91

93 94 96

97 98 98 99

101 101 102 103 103 105 108 112 112 112 114 115 117 130 151 151

153 154 154 155

APPENDIX A, CRACK DIAGNOSIS

Table J: Crack diagnosis Table K: Testing the evidence Table L: Movements and principle causes Table M: Latent defects indicated by pattern of occurrence Property inspec tion record Format for a report

APPENDIX B, MATERIALS REFERENCES

Table N: Thermal expansion coefficients Table 0: Proport ions of render mixes Table P: Render mixes 'lable Q: Mortar mixes

APPENDIX C, USEFUL ADDRESSES AND WEBSITES

APPENDIX D, CD CONTENTS AND USER GUIDE

FURTHER READING

INDEX

CD LICENCE

Cracking mId Building Afllv('IIt('/U

165 167 168 169 171 173

175 177 178 179

ISI

185

187

191

198

Index

aJJrn,c, useful 111 1

age of crack Jelnmillalion 59

alkali-silicaI<' re~H.'lion (ASR) 25 cracking in COllaetc 72

alterations faulty, 1l1()lCrn<,nt resulting fmm 7 overloading and oler stressing 11

arche, .>,'1' lintols and archl" a"e<;<;ing damage :>,'1' damage a,~e~.'>ment

ba!>l:lllt"nts part SI.'(' part basemcnt~

bay window, (JU:.<'S 142

repair 113 symptom, III

~am and block underpinning 10i' blo.;:k"ork

,h('ekk'l I Si concrete

o:'xpansion and ~hrinkage 11 Ill()i~lurt'ftherlllal mO\'l'mt"llt 13

bouncy floor, cau~ .. s 116 repair 116 symptom, liS

brilks Jnd hrickwork Sf!' also building malt'rials cakiurn silicate

cau" uf cracking 74 expan,joll and shrinkage 11 moiSlUrc{Ihamal rnol'ement 13

,"(ekE)l 157 day

... xpansion and )hrinkage 11 moi)lurelthcrmal mon:mt."n1 11

damaged. repair plastering and rendering 114 rebuilding option ll! repairing UJ.:ks 113 replacing britb J I) T!;,pointing 112, 113 ~pallcd hricksJirOSI damage 114

)nap-headcr hritk .... ork see "'all~ \ulphalt' attack

(JUs.,:, 102 repair 102 )ylllptoms 102

building and repairs history of 93

building contract 51!t! ~ontral'lS

buildingdnign inadequate. Inowment arising frum 7,75

ol· .. rloading and owr streSSing El

building materia!~ changes 2 deterioration 8 expansion :lnJ ,hrinkage see expansion and shrink:lgc green materiab, lI~" of 7 n1(li~tureflhcrmal movement .Ice moi,ture/thermal movcment

building mOI'(lllcnl St'l' lllOl'elllcnl Rill/dins RCSII/,lIions IIJ65 I building works super\'i~ion 153

dt'aling wilh sile perlonnd 1501 in,truction book 1501 preparation for and/or rc~ording, dlnkli~ts 155- 163 sit<' inspe.::tion IS.j

calcium silicate brick:. expall'.ion and ~hrink.age II moislUre/thcfmal movemcnt 13

carbonation 25 carpcntT}'

(hc(klisl 158 cavity \,'.1115

corrosion 25 cement mortar 2 cement rendering Sff rendering cement <;creed,

cracking 18 central healing

Illovcmellt nrising from 7 chalk

foundation subsidl'nce 5 chemical action~ 23

alkali·~ilicate r~'action (ASR) 2~

cracking in wncrete 72

repair 103 carbonation 25 curro~ion 25

(avil)' walls 25 emb",dded stet'1 and iron 101 \\all ti",s 101

cracking/mol'ernent rl.'~ul(ing from 6,7. El high alurnina cement (HAC) 73 sulphate attack B

brickwork 102 cracking in wnlf",te 72 foundation~ 25 ground-bcaring slab~ 24, 103 rendering 2·1,102

chimney brcJSIS removal

~'aus",s 1'12 repair 142 symptoms 142

day bricb,'ork expansion and ~hrinki\ge ! I moisture/thl'rma! 1110WII\CIlI 12

clay heave see hl',lW

191

lndC"l(

cla)' )ubwih (racking duC" to "€.'a$Onal 1II0l"t'IIIl'nt 6i foundation subsidence 5

shrinkage of clay )uh~oil, 2i moisture, eff('<1 of 35

da~· pla~ticit)' mdex 36 trC"C"~, C"ffect of 36

dil'nt)

ho\," tTl'l'S damage building) 36 ml'th(xh of tr« ri~k a .... \C~sment 36

dutic'> .. UI clirnatC" change coastal erosion

foundation undl'rmining 1'1 coincident (racking

concrete 72 compression cracks 4 concrete

chl'ckli~t 156 cracking and corro~ion, ,ISSt'SSlTIl'lll 5ef cracking and corrosion

in conere,e expansion ,lnd ~hrinkagc I1 rlIoi)turc/thl'rmal movement 18 undl'rpilllling 51.'C undapinning

concrele hlockwork expansion and shrinkage 11 moisture/thermal mOlement 1.3

conifers ,l'l: trt'C, (om".'r\"a!lOIl arca~

huilding~ in, reralrs 151 stonework IS1

consolidation of !ill bdol\ found.llion, and floor~ 1\

(.Imslru(lillll (Desigll and ,\I<IIlllgt.'melll) Rl.'gularimu 1994 48 con\truelion work

faulty, movement resultin~ from i, i5 contraction Illovement Se.' expan,ion and )hrinkagt' contrad)

building contract 47 ~pecialim 48

erC"atll1g pertO{malKe <arried uut by buth pdflies 45 pra(\icl' uf 47 Icrrm of contract 41'1 the accC"ptance 45 the contract 45 the offt'r ~5

inllriting "16 MispresemarillllAct 1%746 ~Iandard term~ and conditions 46 l'n(.li, ((lIItma Tt'rm$ Art 19ii 46 l'n},/i, Tams ill CO/ISIIII/t" COlllmfls Rt'gllllllioflS 1999 4i

corrosion 25 (a\"ill" walb 25 (tmcretc" sl.'e cracking and corrosion in concrete C"mb.xlded steel and iron i 4

cau~s 101 rt'pair 101 )rmptom, 101

wall tie\ i4 cau"€.'s 102 repairs 101 symptoms 101

crack diagnosb tahle1 165

er,Kking 1 a,)I.'s~nll'nt of 68 change\ in indu,trial and building materials 1 ciilllatC" changC" 1

192

.;ompression cra,ksl cun.;rt'!C sce era,king and .::()rro~iun in (oncrde insurance 1

land)lip I $ub)idcn"

map-pattern cracking 4 monlloring damagt' St'e monitoring damage professional indcmnitr in,uranc ... 2 Il'mion .::rackSI

cracking and corrosion in (Onu,'l ... i I curru-ion of reil1forct'ml'nt i 1

carhOn:ltlon of tht' ,"Onut'le .::ol"er i1 prt'S(.'ne ... ot chloridt's aroull,i tltl' steel 72

.::ra(king aftu hardening i2 dwmical cracking 72 coincidl'llI cracking i2 irost danl<lg," 71 intt' fst'cting ua..:h 72 physi.:a l .::r<l.;king 72 ~tr\lctu fal n,l(king 72 thermal cracking 72

cracking hefor .. h,lrdt'ning 71

damag,' as~ ... \\ment 65 .ategury uf damage

3t'stht'tic 65 ser\"jct'abihtr 65 qabilitv 65

cau."€.' of damagl', anal)")ing 66 cracking 68 ua.::killg and corrosion in conUt'It' jCt' ..:Talking and corrosion

in concret .. degr« and rate of damJgt' 66

nacking due to <;('asonal ~oil movement 67 t'xpan,ion and contraction movement 66 hairlint'trJ,b 67 progrt'ssilt' movement, J"l",sing I\i

l'~'iCntial qut'stioll) 66 failing re taining \1,llIs 67 high alumina cernem (HAC) 7J landslip risk 67 1t'3killg drains 67 recognition Jlld as","'s~mcnt

ht'3\"t't],unag" 6i non-subsidt'llc<' or nOI1-hl';\n" structural mo\"l'mcnt scc

non-sub,idcnn' or non-hl'aw ,tructural mOVCilll'nl ,>uhsiderKt'movement 68

rt'pairingdamage 6l:! de.:iduuus (reC"s<re Ift'eS

dde.:!) inspt'ding and I'\:cordmg .<ee property inSI>t'Clion

design St'l.' building dO:'>ign designers

duties 48 differenTIal ~ubsjJt'n(c 5, JO dilapidation

".;hl-Jule 99 ditcht's

foundation ~uh~idenct' ~ drains

It'aking asSt'ssillg 67 foundation IIndcrmmmg 6,32

le~ts 60,67 drawing'

underpinning 106 dry-pack underpin 101:l

emhankment) foundation )lJb,idcllcl' 6

embedded stcd and iron corro~ion 74

cau .... ~ 101 repair 101 ~ymploms 10!

cn'iuITlt'~

conlr,l(t following Sf( contracts taking 45

excal-ation checklist 155

expansion and ,hrinkage 11 asse~sing damage 66 calcium silicate brich 11 clay hrickwork II COllCrctl' blockwork 11 ma~~ concrete and render I1 natur,11 stone 11 OH'r lintols

,'ause~ 118 repair 118 s}'mptom~ 118

reiniorccd concrete 11 timhC'r II

eXlen~iOIl\

fill

cracking ,It causes 146 repair 148 symptoms I ~6

foundations, de~igning 151

consolidation SfI' con~olidation of till foundation subsidence S

llank waU movement cau!>C) 122 repair

summary 126 ties at cornas and junctions 126 tymg 125,126

symptoms 112 flat roof, Set roofing Moor repairs

,olid floors 11-4 map-pattern (falking 11-4 sloping floon I J.I straight-line cracking 114 untied precast concrete flOOh 114

timher fluors houncyJ1oors 115 .. agsingfloors 116

MOClrs cunwlidation of fill 6 ground-bearing ,lab)

seltlcment 27 sulphate attack 24

repair~ sce fluor repairs settlement 27

foundation, con"(llidalion of fill 6 exten,ion~, designing IS I mO\'<:ment, rep;liring the dMmlge 6R repairs .<'1' substructure repairs scttkmem 5 structural mm"ement}('t· structural mo\ement subsidence .; sulphate attack 25 undHmining 6

frost damas," brickwork I H .-r~,-kin!~ in com:r.:tc i2

gahle, and roof tru~s unbraced

causes 146 repair 146 symptoms 146

geological fault foundation subsidence 5

granular ,oih foundation subsidence 6

ground-bearing slahs sulphate atTack 24

cause~ 103 repairs 103 symptom, 103

gullie. leaking, undermining of foundations 6, B

hairline (TackS 67 hean- )0

foundation suhsidenle 5 protection 109 recognilion and a,,,...)smenl of damage 67

hedges Sl'1' Iree, high alumina cc'roomt IliAC) 73 history oftmilding and repair, 93 110usi/lg Gml1ls, COlIstrl/ctimr lIIui Rry;"III'TIlti()/r .k, 1996 50

indmtrial materials sce "Iro building material-professional indemnil)' illsunlOce 2

inspe,tioil of dcfect~ Si'( property inspection instruction hook 151 internal partitions

ground floor, openings in cau'>('~ 141 r~'pair 141 \)mploms 1-41

upper /1oors,openinp in causes 141 repair 142 srmptoms 111

intersectmg cracb concr~'t(.' i 2

invest igations SfI' property impection isolated blo<:k underpinning 107

)olllt'ry (h«khst 100

Kew'tree to hou~ safe distance' tables .17

land drain' foundation underminlllg 32

landslip insurance I risk of 67

latrnl defects indi(ated b)" !"Iltern of OC(uTTt'lIce table M 169

leaking drains undermining of foundations 6, .1l

level surve), 59 lime mortar 2 lintols and arches

causc\ arch repairs 119 def«tile lintol and arch 119 l'ccentric loading on lintols 1-46 shrinkage or expamion O\"CT lintol 118

linlol failure 74 repair

arch repairs lIt}

/mlex

193

.. " ..

Index

defo;'din' !into! and arch 119 ec~entric loading on lintols 146 ~hrinkage or expansion o\'o;'r linto! 118

~rmploms

arch repairs 119 dehtil't' !intul and arch 119 t'(:centric loading on lintols 146 ~hrinkage or expansion 01 er linlol lIS

li~wd buildings repairs 151

stonework 151

map-pattern ctacking 4 rendering 18 solid !loor)

cau~c~ 114 repair 114 symptoms 114

mass concrett',ff ~OIKrctc mining

foundation ~ubsidence 6 foundation undermining 6,32

Misprl'Sl'l1IaJio" Ad 1967 -16 moisturo;'

dap ~ub~()il" effect on 35 demand, trees J8

moi~lure/thermal mowment 1I calcium sili~a\e brkh I J day brich 12 concrete and render 18 concrete block work I J expansion/contraction 71 methods of controlling thermal mowmcnt 16, 17 moisture movement In mortar, 19 roofs 19-21

metal cOl'erlllgs 19 ripples and blisters 19

timber 19 monitoring damage

levd moni toring 110 precise levelling equipment 81

methods glass tell tales 78 pla)ti, )liding plJI" 711 pre~l'ntation of re~ults and interpretation of dala 80 three screw~ 711 111'0 dot method 77 two serew 80

positioning of devlte) 77 requirem('nt for and frequency of 77

mortar cement mortar 2 lime mortar 2 mixes,tableQ 179 moisture mOI'('ment 19 rcpointing 112,1\3

mOl'emellt 3

194

central heating 7 chemical attack 6 chemical reaction R expan)ion SN! expansion and shrinkage faulty comtruction, alteration and/or rep;lir 7 jJoor~, consolidation of lill 6 fuundations

consolidation of fill 6 repairing the damage 69 settlemo;'nt 5 subsidence 5 undermining 6

grt'('n materials, uS(' of 7 inadequate design, examrle~ 7 material deterioration S moisture/thermal movemem sce moi~turc/thermal mO\'ement monitoring damage ~ monitoring damage natural drying of Mructure and tillishes 8 O\'erloading ~nd o\cr 'tre,sing & ~hrinkage SI'I' expan~ion and ~hrmkage ~tructural Sl.'1! structural movement temperature changes 8 ty~'~ see expansion and ~hrinkap:; moisture/thermal

movement movemt'nt~ and principle cauS('s

tabl .. l 16R

natural stone expansion and ~hrinkagc 11

NH RC tree root 'radii' 3& non-subsidence or non-h('ave o;tructural mo\"ement

recognition ;lIld a~ses~mt'nt 73 hulging walls 7-\ calcium silicate bricb H corro~ion of emb«lded steel 74 lack of lateral restraint 7-1 lintol failure 7-1 poor dc~ign and/or inade\1uate construction 75 retaining wall failure 7-1 roof spread i5 rot in built-in timbcT'> i5 <;culement 7,\ ~ulphate attack 7-1 thermal expansionlcontraction 71 I-ibration 7-1 \,all-tie failure 7-1

owrnlling underpin 10R owrloading and oler ,trcssing &

cau_~e~ 1-13-145 repair 1-13-145 )ymptOlns 143-145

painting checklist 163

parapet cracking causes 112 repair 112 s)'mptotns 122

part bafoCments seulemt'nt

cau~t') 146 repair 146 symptoms 146

Party \\all el(. Art 1996 49 adjacelll excavation~

six metre notict' 19 thrct" metre notice 49

cost of work -19 .. !Ten on exiqing walls 49

peat foundation \uhsidence 6

physical cracking con~rete 72

piled foundations 109 planning supervisor~

duties 49 pla' teTing

checklist 162 damaged, repair 11 -1

plumbing checklist 161

c

principle contractor~ duties -19

profes~i(lnal indemnity in:>uT.lIlCC 2 pmpcriyinspe..::tion 51

futTher im'e,tigalions 58 acceplable degree of tilt 6U ,Ige of crack, dt'lt'rminalion 59 drain test~ 60 movement in leaning walls. recording 60 wilt)'pe and trt~ type, idcnliti(ation 62 ,'ariatiom in le'el. recordin~ 59

gathering information 51 record 171

derelopmcnt of 5i site in~pcction 52.153

in~pection of propert}' 52 recording general site (harad~ristic~ 55 sketching and lllea~uremel1t of cratks 55 ~tarting where crack has be.:'n idcntified 53

~ymptoms 51

rear addition~ cra(king

causes 132 rcpair 132 ,}'mptorllS 131

roof spread or subsidence cau'C~ 131 repair 137 symptom~ 131

records property inspection 57,171

reinforced cOllcrde expan\ion and shrinkage 11 moi,tur .. Jlh .. rmal mo,ement 18

rendering damaged. r"pair 11-1 expan~ion and ,hrinkage 1I map-pattern cra(king 18 mixes

proportions. table 0 177 table P 178

moi,tun:/therma\ movcment 111 <;ulphale attack 14

causes \02 repair 103 ~>'mptom, \01

repairs chemical r .. actions

alkali-silicate reaction 103 corrmion Sft' corro<;ion sulphate attack scc ~ulphaTe alta(k

faulty,mo\-ement rt'~uhing from 7 history of building alld repairs 93 listed buildings 151

,tonework 151 main sub~tru( lure sce 5uh~tructure repair~ super,tructure ;sce sup<:rstructur.:' rt'pairs type nt'cessary onc.:' damage aS~~$('d 68

{.:'pointing 112. 113 report $1'1' th.:' report retaining walls

failing 67 ,ock

foundation subsidence 6 roofing

checklist 159 moisturdthermal movement 19-11

mdal covering> 19 ripples and blisters 19

~pread Sec' roof spread

tTU"SCS sce gables and roof trusses wl1hout parapets. thermal cracking

causes III repair 122 symptoms 122

roof spread 75 ':aUses

bay windows 1-12 chimney breasts. remo,-al 1-12 cracking at eXlemions 146 (Tacking in rear additions 132 cracking in rt'ar addition~, rool spread or subsidence.

ddermination 132

index

([eating openings in internal rarU1ion~.ground floor 141 creating opening~ in intt'rnal partition:>, upper floor 1-11 e((('ntric loading on linlOls 146 kaking lead valleys 138 o\'erloading 1-13 roof spread or bowing wa\l" determination 131 rOiling bonding limbers 146 selllement of part bascment~ !-I6 limhcr roofs 130 unbrac.:'d gable~ and roof trusses 146 uncqualloading on centre ,·alley 137 walls built off floors. first Aoor 139 walls built off floors, ground floor !-IO

leaking lead valleys. r('tlesign 13A repair

bay windows 113 chimneyhrea~ts,re!11ova! 112 cracking at t'xtensions 148 cracking in rear additiom 132 cracking in rear additions, roof spread or subsidence,

determination 132 creatin)!, openings in internal partitions, ground floor 141 creating openinp in internal partitions. uppt"r floor 1-12 eccentric loading on lintol~ 116 leaking kad valleys 1311 owrloading 143 roof ~pread or bowing walls. deTermination 131 rotting bonding timber~ 1-16 selllemt'nt of part ha~ments 146 timber roofs 131 unbraced gables and roof Iru"c~ 1-16 unequal loading on cenlre valll'Y 137 walls built orf Hoors. fi{~t floor 139 walls built off floors. ground tloor \-11

symptom, barwindo\\s 1-12 chimnC} breasts, rcmo'-ai 1-12 cracking at e;'(tensions 146 cracking in rcaT additions 132 cracking in rear additions. roof ~pread or ,ubsidence.

determination 132 creating openings in in ternal p'ITtitions. ground floor 1·11 creating openings in intern;\l partitions. upper floor I'll eccentric luading on Iinlob 1-16 leaking kad valleys 137 overloading 1-13 roof sprt'ad or bowing wall~.determination 131 roning bonding Timbers \-16 senlement of part ba!ot'ments 1-16 timher roofs 130 unbraced gables and roof tru,~) \-16 unequal loading un centr.:' valley lJi walls built off floors, first flour 139 wall~ huilT off f1()or~. ground floor 139

sagging Hoors (auses )16

195

InJt'x

repair \\7 \rmptoms 116

;.(heJule~ of condition 98 S(ht'dulcs of dilapidation 99 se-t(l~mcnt

';(lUS<' of cracking 74 found(uions 5,27 in other parts of structure 27 part basemC'nls

'>Cwcr\

';,1US<:S 146

repair 146 ~rmptoms 146

foundation ~uhsidence 6 ,hrinkagc 5/'t' expansion and ~hrinkagc )it~ imp,'dion ~t'/' propnty inspection site pC'rsonnc1

dt';Iling with 15·1 sloping tloors

causes 114 repair 114 ~yrllptonlS 114

~(lil set' subsoils 'palled brich 114 )p<..'Cificalion~ 97

collection pagl' 98 conditiom of contract 97 CO\'t'r pagl' 97 dJ}'works and contingencie~ 97 gener,ll conditions 97 schedule of works 98 'lX'citic conditions 97 trade preamhles 97

Mec1 or T(:inforcoo concrl'te frames t'xpan,ion

caUl>(!) 119 ft'pair 122 symptoms 119

~tonew'ork repairs listed buildings 151

Mraight-line cracking Mllid Aoor~

c;\U~c~ 114 rt'pJir 114 s}'mptoms 114

Slreams foundation subsidence 5 foundation undermining 6

~tructural cracking concrete T2

)trudural mlJ\'l'ml'nt 17 day hca\<.: 30 foundation subsidC'ncC' 27

shrinkagt' of day sub,oils 27 found;l\ion undermining

leaking drains or presence of land drains 32 miningopo:ratinns 32

n()n-~ub~idl'n(e or non-heave sce non-\uhsidcnn" or non­heaw structural movement

iK"ttlemcnt foundations 27 in other parts of structure 27

suhsidence differentialS foundations 27

causc~ 5

,%

shrinkagt' of day sub~()il~ 27 indicators 6lI insurance 1 r«ognition and as..'iCs.~ment of mo\'ement 6R

subsoils J.t't also clay subsoils trpt', idl'ntification 62

\ub\truLlurc repairs 103 cau~e~ 103 repair $t't' underpinning symptoms 103

~ulphate attack brickwork

causes 102 repairs 102 5)mptoms 102

'au\(' of cracking 7-1 changes due 10 23

cTacking in (Onerelt' 72 foundations ~5 ground-bl'aring slabs 24

causes 103 repairs 103 symptoms 103

rt"ndt'ring 24 cau'\Cs 102 repairs 10] symptoms 1O~

super5tnKturl.' rl'pairs t}pi(al spc-cifications 112

floor repairs see tlOOt repairs repair of damagt'd brickwork ,/'t' brkk~ and brickwork roof spread Sf't' roof spread tht'rmal cracking s<'e thermal cracking rcpointing 113

.,upervisioll of building works st'/' building works supervision

lemreratur~ changt.'~ SI'f' moisture/thermal mo"emt.'nl; thermal cracking

1o:'n5ion uacks -I

testing the evidence table t.: 167

thC'report 1:19 appendkt"s 91 as.sumptions madl' 91 conclu.,ions and recommendations 91 c()pic~ 91 tirst page 90 format 17] front cuwr 89 index 89 larnut 91 ~lgnalure 91 technical ill\-t"~tigation 90

thermal cracking 8,72 ,aU)l'~ 117

arch repairs 119 dcfectiVt' linto! and arch 119 expansion of steel or reinfuf(CU wnnc\c fram." 119 parJp<..'t cracking 122 roof\ withnut parapets 122 ,hnnkage or expansion owr lintol 11!j

flank \,'allmo\"t'mt'nt Sl't' flank \\0111 movt'mt.'nt repair 117,118

af(h repairs 119

dcfl'ctiwlintolalldarch 119 expansion of steel or reinfor""d conut'lt' frame 122 parapet cracking 122 roofs without parapets 122 shrinkagl' or expansion over linlol 1111

)ymptoms 117 arch repairs 119 defe..:th't' lintn! and arch 119 expansion uf stl'cl or rcinforn'd conerl'te framc' 119

parapet cracking 122 roofs without parap~b I:!~

shrinkage or expamion Ol'er Ilnto\ 118 Iherll1;11 expansion cudli.:ienTS

lablcN 173 Tilt

;Icceptahl~ degT ...... of 60 Tlmbcr SC(' IIlso building material,

built-in limb ... rs, rotting i5 l'xPJn~ion and shrinkage 11 Il(/Or~, r"'pairs,er' !loor r.:pain moi~ture/thcrmal mo\'~m~nl 19 roofs, spread se(' H/Of ~pr ... ad

tre<.'3 35 dJ\' suh'iOiJ.., eff~(1 on .16

. how trl~~ damage building\ 36 meThod~ of Iree risk a.'\ses~m,'nl 37

foundation ~ubsidence 5 mCThod, of tree risk a_,ses~n1l'nl

K,'w '1ft"'" to hous<:: saf~ dblance' tab1c~ 37 mui~lur ... demand 39 !\HllC tree root'radii' 38 worked example 40

pruning 68-71 root damage

J~sessing and r ... pairing damage 68 Rnot iJ.mwgl' by m'cs I

~olUlions lu root problems iO Tre~ Prc~r\'ation Orders (TPO~) 68 typl',iJt"llli/lc<ltion 62

tunnd~ fuundation suhsidcnc~ 6

undermining of foundations 6 leaking drain~ or presence of land drains 31 mming operaTions 3:!

underpinning tYri,,1l ~pedfication clau~s

heal'e protection 109

pil ... d foundations 109 IUl\itiona\ underpinning 108

typical specificariom \05 beam and bl(}(k ,y ... km of underpinning 107 drawings 106 dry-pack underpin 108 isolated hlock underpinning 107 overfilling undt"rpin 108 Iraditional massconcreTc underpinning 107

L'I1{airCOIrlmcI1i>rmsAcI19i7 46 t";",ir '1j'f/lu ill Consumer COllfmc/5 Ikgu/,lIiolls 1999 17 unti~ll precast concrete ftoor~

causes 115 repJir 115 symptoms 114

vihratlon cau<;(.· of cracking 74

wa\b bulging 74 eff«1 of roof spread on set' roof spread lIank wall movement we flank wall movcml'nt leaning, recordingmovcment 60 Pi/rty hall ere. Act 1996 sre p"rt)' I\all rle. At'1 1996 plumb line survey 60 reTaining, failure 67,74 ~nap-h<'adt"r brickwork

calL~t"S 132 rep'lir 132 symptoms 132

wall-tie. corrosion 74 causes 102 repair 102 ~}'mptum~ 101

weh~iTc~

u,c:ful 181 wclb

~ub~idcnce, causes 6

Tndc).

197