1、CODE OF PRACTICE CP 143 -5: 196 4S heet roof a nd wa llc o v ering s Par t 5 :ZincUDC 6 9.024.156 + 6 9.022:669.5CONFIRMED DECEMBER 2007Licensed Copy: :FULLNAME, : DATE, Uncontrolled Copy, (c) BSICP 143 -5: 196 4T his p a r t of the C odeof P r act i c eh a s b eenprepa redb y ac ommi tteec onv ened
2、 b y theC odes ofP r act i c e C ommitteeforB u ilding. Hav ing b eenendors edb ythe C o u n c ilfor C odes ofP r act i c e , i t w a s p u b lis hed undert he a uthori ty of the G enera lC o u n c ilon7 Oct o b er196 4 BSI 02- 2000T hefollow ing BSI referenc e s rela t e to the workof this C odeofP
3、 r act i c e :C ommitteereferen c e BLCP/ 4 / 1D r a f t for c ommen t D 63/1 2684ISBN 0 580 3 4555 6D r a f t ing su b - c ommittee BLCP/ 4 / 1 zincco v erings for roofsG uy B i s c oe, C h a irm a nR . M . E d w a rds A sso c i a t ion of B rit i s h R oofing F elt Man u f acturersC . H . Farra r
4、D . S . I . R .B u ilding R e s e a r c h S t a t ionC . E . Cannons I n sti tution of S t r u c tur a l E ngineersH . E . G olledge M e t a l R oofing C ont r act ors A sso c i a t ionE . S . L e s lie M inistr y of P u b licBu ilding p u rpos ema de sheets ofo t herdimens ions can b eob t a ined.A
5、 tableof weights, g a u ges a nd thic knesse s ininc hes of zinc sheets i s giv eninC l a use 602 a ndi s bas edont he weight ofone sq u a refoot ofinc h thic kma t eria l.I t s hou ldb eno t ed th a t t heE nglis h Z incGa u ge,as distinc t from theS t a nda rdW ireGau ge, ris e s inn u m b er wi t
6、 h thic kness.O nperma nent b u ildings , roofc o v erings a nda n c illa r y p a r ts s hou ldnot b e thinner th a n N o.14ZG( a pprox ima t ely21 SWG).N oexterior zinc work shou ldb e thinner th a n N o.1 2 ZG( a pprox ima t ely23 SWG).202 NailsNails shou ldb eof steeleit herhea v ily g a l v a ni
7、z edoro t herw i s eprov ided wi t h a zincco a t ingofequ i v a lent t hic kne ss. T hey s hou ldc omply w i t h BS 1 202 4). Gal v a niz edc lout n a ils not less t h a n1inlong shou ldb eusedforfi x ing the zinc .203 ScrewsScrews shou ldb eof steelc o a t ed simila rly to steeln a ils a nd shou l
8、dc omply wi t h BS1 2 1 0 5).2 ) BS 271 7 , “ G lossa r y of terms a pplicable toroof c o v erings ”.3 ) BS 849, “ P l a in sheet zinc roofing”.4)BS 1 202, “ W ire n a ils a nd c ut n a ils for b u ilding p u rpos e s ”.5)BS 1 2 1 0 , “ W ood sc rews”.Licensed Copy: :FULLNAME, : DATE, Uncontrolled C
9、opy, (c) BSICP 143 -5: 196 42 BSI 02 - 2000204 U nderla yS u i t ablem a t eria l s for underla ys a reopen-t e xturedimpregna t edfelts suc h a s t hos edefined underT y pe4 A ii),BS 7 4 7 6 ).Mat eria l s o t her th a n thos edefinedabo v ema y b e us edprov ided th a t t hey a reporous a nda reno
10、t liable tob e c ome“ t ack y ”in serv i c e.205 S older a nd soldering fluxe sS olderfor us eon zinc shou ldb e a n t imony free,andeit her5 0/5 0 or 60/4 0tin/ lea d ,corres ponding togr a des FandK inBS 2 197 ). T heflux genera lly usedi s z incchloride solution( c ommonly know n a s “ K illed sp
11、irits”)eit hera loneor wi t h thea ddit ionofa mmoniu m c hloride.T herea rea l s opropriet a r y non-acidliqu idfluxe s w hic h a reequ a lly sui t able.W hen the su rface s t o b e solderedcannot b epre-c lea ned, h y droc hloricac id( c ommonly know n a s “ S pirits ofs a l ts”)m a y b e us ed.F
12、l ux res idu e s shou ldb e wa s hedoffjoints immedia t ely onc omplet ion.206 R oll cappingS q u a re se c t ionrollcapping( s eeF igu re4)i s m achinem a defrom zinc sheet a nd sh a llb eof the sa met hic kne ss a s t heroofc o v ering.I t i s usua lly suppliedinlengt h s of8ft ,but s hou ldnot b
13、efi x edinlengt h s ofmore th a n4ft .S e c t ion 3. D e s ign c ons idera t ions301 C h a r act eristi c s of zincZ inc i s aba s i c non-ferrous met a l , light grey inc olou r a ndofabo ut t he sa medens i ty a s steel.I t i s c ommerc i a lly a v a ilableina rela t i v ely p u reforma s s heet ,
14、 st ripa ndn a ils .I n thecast form, zinc h a s aco a r s e c r ysta lline str u c ture. B y rollingint o s heet or st rip t his i s red u c ed torender them a t eria ldu c t ile wi t hgood workingpropert ies . T hephysi calpropert ies of zinc sheet a regiv eninC l a use 601 .O nex posure to thea t
15、 mos phere, theb right met a lre a dily forms a n a dherent a ndmodera t ely prot e c t i v ec o a t ingofbas i cca r b ona t e , whic hre sul ts in the surface we a t hering to a stablem a tt grey .302 D u r abilityT hed u r ability of zinc roofingdepends c hiefly on the thic kness of the zincandon
16、 the ty peofa t mos phere tow hic hit i s e x pos ed.T hem a int ena n c e-freelifeofa z inc roof, properly l a id w i t h a sui t ableg a u geofmet a la nd to a dequ a t efa lls , i s u p w a rds offorty y e a r s u ndera v era ge ur ban c ondit ions .I n somea t mos pheres , thepit c hof theroof w
17、illeffec t i ts d u r ability. W hile theeffec ts ofr u r a lorma rinea t mos phere s a re very s light , the sulph u r acids inhea v ily pollutedind ust ria l a rea s a ttack zinc morer a pidly . S u c h a ttackde c rea s e s w i t hin c rea s ein thepit c hof theroof, sinc e c orros i v e su b sta
18、 n c e s a remoreeffec t i v ely wa s heda w a y b y r a in.Z inc i s not res i sta n t to acids or stronga lka lis .303 P ropert ies a ffec t ing des igna ) C ont act w i t hot herme t a l s . S heet z inc i s susc ept i b le toelec t roc hemical c orros ionifplacedinc ont act w i t h , orifi t rec
19、 eiv e s wa t erdra iningfrom c opperorc opper-ric h a llo ys. T h us, wa t erfrom acopperroofs hou ldnot dis c h a rgeon to a zinc su rface su c h a s a g utterorr a inw a t erpipe.T heo t hermet a l s (iron,a l u mini u m a ndi ts a lloys, lea d a nd tinma n s s older)likely t o c omein t o c ont
20、act w i t h z inc inb u ildingc onstr u c t ion , h a v eno t b eenfo u nd to cause trou b le.W herec opperlight ning c ondu c t ors , vent pipes e t c ., p a ss o v er zinc roofc o v erings , thec opper shou ldeit herb e tinned(i.e. w i t h tin/ lea d solder)ora l t erna t i v ely c o a t ed wi t h
21、in sul a t ingm a t eria l.6 ) BS 7 4 7 , “ R oofing felts ( b i tumen a nd fluxed pit c h)”.7 ) BS 2 19, “ S oft s olders ”.Licensed Copy: :FULLNAME, : DATE, Uncontrolled Copy, (c) BSICP 143 -5: 196 4 BSI 02 - 2000 3b ) C ont act w i t h timb er. Z inc shou ldnot b ela idindirec t c ont act w i t h
22、norrec eiv edr a ina gefrom, we sternredc eda r , o a kor sw eet c hestn ut.W here zinc h a s to b ela ido v er thes ema t eri a l s ,afelt underl a y shou ldb eprov ided.S e a s oned softwoods , wi t h thee x c ept ionof thos ement ionedabo v e , donot a ffec t z inc,s ee S u bcl a use 305 a ).c )
23、C ont act w i t h c ement , mort a r a nd c onc ret e. Z inc i s not a ffec t edb y s a nd/ c ement or sa nd/ lime/ c ement mort a r s m a de wi t h c lea nma t eria l s . I nit i a lly a slight e t c hingact ion ta kes place ,but t his c e a s e s onc e themort a rha s s e t . I f z inc fla s hings
24、 e t c .,areemb eddedin, orc omein t o c ont act w i t h , w a llingma t eria l sc ont a ining a pprec i ablea mou n ts of solu b le sa l ts (not abl y c hlorides a nd su lpha t e s ) , themet a lma y b ea ttacked ,andin suc h cas e s shou ldb e c o a t ed wi t h a h a rddry ing b i tumenpa int .d)C
25、 ondens a t ion. C ondens ed wa t erif tr a ppeda g a inst the under s ideof zinc roof c o v erings , i s liable toa ttack themet a l.R i s kof su c h a ttackis redu c edb y v ent ila t ing theroof st r u c turea ndfollow ing therec ommenda t ion s inC l a use 305 .e)P rov i s ion for therma lmo v e
26、ment . Z inc h a s ,among thec ommonmet a l s a rela t i v ely highc oeffic ient oft herm a lex p a n s ionfor whic hdu e a llow a n c e shou ldb ema deinroofinga ndo t here xterior work.T het herma lmo v ement ofa n8foot lengt hof zinc sheet i s abo ut ! infora tempera ture va ria t ionof1 00 degF
27、(56 degC ).Z incco v erings onroofs orint egra lgutters shou ldnot b ela idinc ont inu o us lengt h s (i.e. w i t hdo u b le-w elt edor wi t h solderedjoints)grea t er th a n 20 f t .304 R oof pit c hT hepit c hoffu lly support ed zinc roofs a ndofg utters int egra l wi t h them shou ldprov idea deq
28、u a t efa ll toc lea r wa t erfrom them; thef a ll shou ldnot b ele ss th a n 2 inc hes in1 0 feet . T herei s nolimit a t ion to t hesteepness ofpit c h.305 S u b str u c tureT he su b str u c ture shou ldb ede s ignedinaccorda n c e wi t h theC odeoff u n c t iona lrequ irements ofb u ildings ,CP3
29、 ,Ch a p t erV 8),and shou ldb e windt ight , dimens iona lly stable, inert a ndfreefrom spring.T hedec kings hou ldb e cap ableof support ingmen workingoni t w i t hout perm a nen t distort ion.F elt u nderl a ys a ree ssent i a l wi t h c onc ret e su b str u c tures ,anda rerec ommendedon timb er
30、 su rface s ,but wi t h some ty pes ofc ompos i t ion b o a rddec king, fel t m a y not b erequ ired.Z inc shou ldnot b ela idinc ont act w i t h su rface s w hic ha ttr act moistu re, or whic h a llow c ondens a t ionfromins ide theb u ilding to b e c ome tr a pped under themet a l.O neof thef u n
31、c t ions of theporous felt u nderla y i s t o a llow t he unders ideof themet a l to b rea t he.I t s hou ldb eno t ed th a t drips , not less t h a n 2 indeep, m a y b erequ iredonroofs pit c heda t less t h a n15 .a ) T imb er. A llb o a rding shou ldb e well se a s oned softwood, ofnot less t h a
32、 n1innomina l thic kness,preferabl y q u a r t er sa w n a nd wrou ght on thef ace , tore c eiv e the zinc . B o a rding shou ldb ela idin thedirec t ionof thef a ll, or, if this i s rendereddiffi c u l t b y t hec onstr u c t ionof theroof, dia gon a lly , s inc e a n y w a rpinginb o a rds l a ida
33、cross the slope, e s pec i a lly onroofs oflow pit c h , willprev ent r a inw a t erfromr u nningofffreely .T heb o a rds shou ldb erigidly fix eda ndjoints sta ggered.T hehea d s ofn a ils shou ldb e wellpu n c heddow n ,anda ll sc rews c o u n t ersunk. I f timb er trea t ed wi t h a pres erv a t
34、i v eis usedforb o a rding, rolls orr a f t ers c omingin t o c ont act wi t h zinc, thepres erv a t i v e shou ldb enon- c orros i v e.T imb er trea t ed wi t hfireret a rda n ts bas edon sodiu m silicat e a nd sodiu mphos pha t eis not likely t ocause trou b le.b ) C onc ret e. T he su rface shou
35、ldb ela id toev enf a lls a ndprov ided wi t h a smoot hfinis h.F i x ings forc lips a nd woodrolls a reb e st m a de wi t h c ompos i t ionplu g s int o whic h sc rews a redriv en.I f timb erbattens a reused, they s hou ldb epressure trea t ed wi t hpres erv a t i v e s , seeCP 9).c ) O t herform s
36、 of dec king. Various c ompos i t ionb o a rds or sl abs h a v e b eenfou nd sa t i s f act ory forprov idingacont inu o us str u c tur a lde c king.T hemet hods of se c u ring the zinc sheet ing(i.e.fix ingforrolls a ndc lips )m a y h a v e t o b e a d a p t ed to sui t thepropert ies of t hep a r
37、t i c u l a r typeofm a t eria l spec ified,andc ollabora t ionb e tween t he z inc roofingc ont r act ora nd t hem a inc ont r act ori s des irable.8)CP 3 :Ch a p t erV,“ L o a ding”.9)CP., “ P res erv a t i v e trea t ments for c onstr u c t iona l timb er”(inc o u r s eofprepa r a t ion).Licensed
38、 Copy: :FULLNAME, : DATE, Uncontrolled Copy, (c) BSICP 143 -5: 196 44 BSI 02 - 2000T hemet hodoffix ing shou ldprov ide se c u reda n c hora gea t lea st equ i v a lent t o th a t prov idedb y fix ingw i t hna ils or sc rews int o so u nd timb er.T he su rfaceof thec ompos i t ionb o a rdor sl ab sh
39、 a llb e su c h a s t opermit fix inga nddressingopera t ions to b e carriedo ut w i t hout d a m a ging thedec king.306 J ointsa ) R olls . S h a ped woodrolls ( s eeF igu re 3) a re us ed toprov idejoints r u nning wi t h thef a llof theroof,anda t hips a ndridges .b ) C ross join ts. J oints b e
40、tween theends of sheets a rem a deb y mea n s of singleloc k welts forroofs pit c heda t 15 or st eeper.F orlow erpit c hes , joints a regenera lly m a deb y mea n s ofdrips w hic h shou ldb eno t less t h a n 2 indeep.307 S pec i a lfe a turesW heno t herroof su rface s dis c h a rgedirec t l y on
41、to a zinc roof, the zincco v ering shou lde xtend under thea djoiningrooffor a dista n c egi v ing a vert i calheight of 6 in.W hena zinc roofdis c h a rges o v ero t herroofsurface s ,a sepa r a t e zincapron shou ldb eprov ided, the upperedgeof thea pron to b eenga ged wi t h theroofs heets,and th
42、elow eredge st iffened wi t h abe a dorfold.308 T herma lin sul a t ionT he therma l c ondu c t i v i ty of zinc i s high,andforpract i calpu rpos e s t heeffec t ofa zincco v eringm a y b eignored whene stima t ing the therma lre s i sta n c eof a roof.P rov i s ionfor therma lin sul a t ion shou l
43、db ema dein thedes ignof the su b str u c ture.Z inc roofingrea dily abs orb s s ola rhe a t; t his abs orpt ioncan b eredu c edb y c o a t ing wi t h a su i t ablep a int .309 F ire prot e c t ionZ inc sheet i s non-c omb usti b lea nd thereforei t w illnot i tselfc ont rib ute tofire sprea d.A s a
44、 roofc o v ering,t hec l a ssifi cat ionob t a inedb y z inc in the te st pres c rib edinBS4 76- 3 1 0 ) willdependon them a t eria l s w i t hw hic hit i s a sso c i a t edin thec onstr u c t ion.3 1 0 P rot e c t ion a g a inst light ningZ inc roofs donot pres ent a n y spec i a lha z a rd.R efere
45、nc e shou ldb ema de to CP 326.10 1 11). A ttent ioni s dra w nin th a t C ode to thenec e ssi ty forprev ent ingdirec t c ont act b e tweenbarec opperc ondu c t ors a nd zinc,onacco u n t of theris kofelec t roc hemical act ion, seea l s o S u bcl a use 303 a ).S e c t ion4. M e t hod of l a y ing
46、a nd workma n s hip4 0 1 P rot e c t ion a nd st ora ge on si t eS t a nda rd zinc sheets a re su ppliedfla t , orinrolls ,and st ripinc oils . T hem a t eria l shou ldb e st oreddry u nderc o v eronaclea n , fla t surface c lea rof thegrou nd.S heets m a y b e st oredfla t ,androlls orc oils stoodo
47、nend.P reformedroofing sheets deliv ered to the si t e shou ldb ene stedor st ackedin su c h a wa y t h a t nodistort iono ccu r s . P reformedcapping, usua lly deliv eredin8ft lengt h s , shou ldb e simila rly nesteda ndprot e c t edfromd a m a ge.U nderl a y felt a nd woodrolls s hou ldb e st ored
48、dry u nderc o v er.4 02 P repa r a t ory w orkW hen sheets a re to b eformedon si t e ,a sp ace u nderc o v er shou ldb e a llocat edfor use a s a w orks hop.T hew ork s hop shou ldaccommoda t e a timb erb enc h10 feet longb y3feet w ide whic h shou ldb eprov ided wi t ha nov ers a ilingmet a l stri
49、p, the workingedgeof whic h s hou ldb e slight l y rou nded.T he w orkb enc h s hou ldpreferabl y b e c omb ined wi t h the st ora ge sp ace. N o spec i a l scaffoldingi s requ ired b e y ond th a t norma lly pro v idedforre a d y acc e ss to theroof su rface.Facilit ies forhoistingm a t eria l s t o theroof shou ldb eprov ided.T heroofde c king shou ldb e a s rec ommendedinC l a use 304 ,andina ddit ion shou ldb edr y a nd sw ept c lea nb eforela y ing the underla y felt . T hefelt s hou ldb edr y a ndfreefromdeb ris b eforec o v ering wi t h zinc .1 0 ) BS4 76, “ F ire te sts
