Fire separations in the National Building Code (1953)

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Fire separations in the National Building Code (1953)

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N.ATIONAL RESE-ARCH C O U N C I L O F CANADA D I V I S I O N O F B U I L D I N G RESEAZCH F I R E SEPARATIONS I N TKE N A T I O N A L B U I L D I N G CODE

(1953)

by J.N. R a t n i c k and R.S. Ferguson Report Yo.

135

of t h e

Division of Building Research

Ottawa

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PREFACE

When t h e N a t i o n a l B u i l d i n g Code vias r e v i s e d i n

195'3

t h e regulations f o r 1;he p r e v e n t i o n of f i r e spread were completely r e w r i t t a n i n a form and language more

s u i t a b l a t o the r e g u l a t i o n s o f a r c h i t e c t u z a e a r d b u l l d i n g today, I n a c c o p t i n g a new approach based on r e c e n t

t h e o r i e s i n f i r e eng-inoerLng, t h e A s s o c i a t e Conmiittee

a n t i c i p a t e d t h a t a h i g h e r degree of s a f s t g would be p o s s i b l e a t l e s s c o s t t o t h e oiirner and w i t h l e s s r e s t r i c t i o n on

d e s i g n e x p r e s s i o n . I t was r e a l j z u d , however, t h a t a

compromise had t o be made w i t h the i d e a l approach i n o r d e r n o t t o e f f e c t t o o g r a a t a d e p a r t u r e from c u r p e n t p r a c t i c e ,

Even the b e s t r e g u l a t i o n s a r e of l i t t l e valile i f they a r e n o t c l e a r l y understood. T h i s r e p o r t h a s been p r e p a r e d a s a n e x p l a n a t i o n of t h e r e g u l a t i o n s s o t h a t m i s - u n d e r s t a n d i n g s a r i s i n g from t h e i r use w i l l be l e s s e n e d .

J O N * Katnick, a r c h i t e c t u r a l s t u d e n t a t t h e U n i v e r s i t y o f

B r i t i s h Col~ullbia, p r e p a r e d t h i s r e p o r t w h i l e on t h e s t a f f o f t h e D i v i s i o n t h i s p a s t s m o r . R o s e Ferguson, S e c r e t a r y o f

t h e A s s o c i a t e Conunittee on t;he N a t i o n a l B u i l d l n g Code, guided h5s i n v e s t i g a t i o n s .

This papor, w h i l e answering some q u e s t i o n s , w i l l undoubtedly r a i s e o t h o r s . It; i s hoped t h a t , through t h e comnients a12d s u g g e s t i o n s of r e a d e r s , which w i l l be melconed, t h e f i r e r e g u l a t i o n s i n t h e N a t i o n a l B u i l d i n g Code can be s t i l l : f ' u r t h e ~ improvede Ottawa December

1957

R.F. Logget D i r e c t o r

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TABLE OF CONTENTS

Page 1. DEVELOPMENT OF THE SCIENCE OF FIRE PROTECTION

.

rn 1

a. Research Work . . . m m ~ . m ~ a m ~ m ~ . . m m m ~ ~ ~ ~ ~ ~2 m . ~ ~ . m . ~ ~ ~

b. F i r e Resistance T e s t s . m m m . . m e m e ~ m ~ ~ m ~ m ~ ~ m m e ~ m m ~ ~ 2

c. Thermal R a d i a t i o n from Burning Buildings

. .

,

.

,

. .

4

2. THE: NATIONAL BUILDING CODE . m m m m m m m m m m m m m m m m . m m a o . m .

5

a. F i r e Regulations . . . m . . . m . m . m m m m m m e m e m m m m

6

b. F i r e S e p a r a t i o n s Defined m . ~ , . ~ ~ m . m m ~ e m m m m m m ~ . o o ~

6

c. Grading and Requirements of S e p a r a t i o n s

.

....

,,.

7

d. F i r e S e p a r a t i o n Be tween Bulldings

.

,

.

. . . .

.

. . . .

.

1 0

e m S e p a r a t i o n by F i r e Walls .m,.,mem..m,,,....mmmmm. 12

f . F i r e S e p a r a t i o n Within Buildings ~~me,..,.ma.m~.m 15

(5)

F I R E SI1PAR"ITIONS Y

-

-n--CI---

Records shoiPl t h a t a l a r g o p r o p o r t i o n of P m r l c a n and Canadian c i t i o s have boen subjected t o a c o n f l a g r a t i o n a t somg time d u r i n g t h e i r h i s t o r y , Thoso conPPagrwtions s t a r t e d un-

p r e t e n t i o u s l y a s does a l z o s t evszy firoQ S i n c s t h e r a was u s u a l l y

vopy l i t t l e r e s i s t a n c e g i v e n t o the f i r e , hoaavsr, i t spread u n c o n t r o l l s d from b u i l d i n g t o b u i l d i n g , l a y i n g n a s t e l a r g s a r e a s ,

sapping t h e econolny o f t h e c i t y , and causing a t r a g i c l o s s of l i f e . Dming t h e o a r l y developmeri'c of h n e r i o a , c i t i o s o f t e n grew r a p i d l y and w i t h l i t t l e c o n t r o l .

1, DEVELOPILENT OF THE SCIENCE OF FIRE PROTECTION

A s a r e s u l t of t h e s e e a r l y c o n f l a g r a t i o n s , regulatj.ons t o l i m i t the use of m a t e r i a l s t h a t prosontsd a p o t e n t i a l f i r e hazard were developed and g r a d u a l l y tho p r a c t i c e of requLring more s o l i d

" f i r e p r o o f v construc t i o u s p ~ o a d , p a r t L c u l a r l y i n the conges t s d d i s t r i c t s which were u s u a l l y tho v i c t i m s of such c o n f l a g r a t i o n s . Despito a t t e m p t s t o combat them, c o n f l a g r s t i o n s continued and so-

c a l l e d firoprool" b u l l d i n g r T j j e r e g ~ t t c d a l o n g with t h o r e s t .

Gradually f i r e departments bocalno more e f f i c i e n t , w a t e r supply was improved, and more effective methods of c o n s t r u c t i o n t o p ~ e v e n t f i r e spread were developed, I n tfuio kmovlodga of f i r e behavior and f f r e defence bocnms more r e f i n e d and the g e n e r a l problem of t h e holocaust could be countered by s p e c i a l i z e d p r e c a u t i o n s a g a i n s t b e t t e r - d e f f ned hazards. b7ith t h e ~ i d of l a b o r a t o r y r a s e a r c h , mays

of measuring f i r e i n t e n s i t i e s and t h e e f f e c t i v e n e s s of p r o t e c t i o n were devised, This f i e l d of knowladgo i s bscorning known a s f i r e

e n g i n e e r i n g

I t i s l a r g e l y upon t h e now knowledge of f i r e e n g i n e e r i n g t h a t the f i r e requiremsn2s of t h e Natlonal Building Codo a r e based. Tha requirainents a r e a refinonon@ over previous r e g u l n t f o n s and

make p o s s i b l e t h e dsslgn of b u i l d i n s s which have g r e a t e r f i r e s a f e t y provided a t l e s s c o s t t h s n has p r e v i o u s l y boon p o s s i b l e , An

understanding of t h e terms usod and the functions t h a t have boen developed a s a r e s u l t of r e s e a r c h i s d e s i r a b l e i f t h e s e r e g u l a t i o n s a r e t o be a p p l i e d to b e s t advnniiago. m-2 next Eon paragraphn

d e s c r i b e t h e f i r e r e s o a r c h and f i r e engineering t h a t apply. A f u l l d i s c u s s i o n of t h e f i r e s o p a r a t i o n requirements of the N a t i o n a l

(6)

Research Wo~li

-

Among t h o e a r l i e s t r e s o a r c h norlr conducted n a 3 t h a t of t h e F i r e O f f f c e s C a m n i t t o e formsd

In

B r i t a i n in 1858, This

Comnittos becar.13 Yno B r i t i s h Fil-o P r o v e i ~ t i o n Con-littoe i n 1897 (1). I t s major tnslr was t o perform t e s t s so t h s t d a t a conearning the

f i r e r e s i s t a n c e of vapioun m a t e r i a l s and systoms of c o n s t r u c t i o n used i n b u i l d i n g p r a c t i c e could ba compiled, and t h a t particulars concerning f i r e prevenl5vo, f i r o alarm, o r f i r e e x t i n g u i s h i n g a p p l i a n c e s could be c o l l e c t e d . By t h 3 end of the c e n t u r y many d i f f e r e n t m a t e r i a l s had bscn s u b j e c t e d t o t h e s e t e s t s , and t a b l e s f o r a s s i s t a n c e t o b u i l d e r s had boon dravm up r e c o r d i n g the f i r e r e s i s t a n c e of f l o o r s , c e i l i n g s , doors, p a r t i t i o n s and the l i k e .

E a r l i e r s t i l l i n the United S t a t e s , due t o t h e l a r g e nunber of d i s a s t r o u s f i r e s , tho Undorvxbiters t L a b o r a t o r i e s I n c o r p o r a t e d w a s formed i n 1894 by a group of Anzoriccln insurance companles (2).

I t s f u n c t i o n s a s s i m t l a r t o t h o B r i t i s h F i r e Prevention Committoe. Various types of equipment, a p p l i a n c e s and m a t e r i a l s were t e s t e d t o meet s a f e s t a n d a r d s of f i r e p r a c t l c a . This o r g a n i z a t i o n a l s o

published l i s t s of p r o d u c t s t h a t were t e s t e d and found acceptable. hlucli o f the m a t e r i a l gathered by t h e s e e a r l y a s s o c i a t i o n s

h a s been superseded by l a t e r developments; t h e p r i n c k p l o s forrnu1,sted prove v a l i d today, however, and, i n nany c a s e s , have fornied a

valuable foundation f o r l a t e r posearche b. F i r e Resistance T e s t s

I n t h e courso of time, i n v e s t i g a t i o n s i n t o t h e f i r e r e s i s t i v i t y of m l t e r i n l s l e d t o the development of standarcla

f o r comparing t h o r a s u l t s of t e s t s of d i f f s r e n t k i n d s of components c a r r i e d o u t by d i f f o r s n b o r g a n i z a t i o n s i n d i f f e r e n t p l s c e s , and i n both England and tho United S t a t o s pormanont t e s t i n g s t a t i o n s were s e t up by t h o govormnsnt, Stliadard furnacos and t o s t i n g proceduram Vera develop2d so t h s t m a t e r i a l s could be t e s t e d under

c o n d i t i o n s c l o s e l y approximatfng tfioso of a c t u a l p r a c t i c e , The

s t a n d a r d s f o r t s s t s are reasonably con~parabla botneen c o u n t r i e s , and w i l l become mom so a s t h f s t e c h i q u o dovelopso Tho e x t s n t t o whish w a l l s , C O ~ I ~ I ~ I I I ~ , f l o o r s , and types of cons'cruction a r e a b l e t o withstand f i r e i s rocordod by t h e s e t e s b s , The hmgrican S o c i e t y f o r T e s t i n e M n t e r i a l s has proscribed m thods ~ v h l c h measure and

s p e c i f y according t o a con3mon standard, t h e f i r s r a s i s t i v s p r o p e r t i e s of m a t o r f a l s and assenlbliss. This s t a n d a r d i s a 7 p l i c a b l s t o a mide variety of c l a t o r i a l s , s i t u a t i o n s , and c o n d i t l o n a of oxposwe

( 3 ) .

I t I s i n t o r o s t f n ~ t o noto how a b u i l d i n g component i s s u b j e c t e d t o f i r e c o n d i t i o n s i n a f i r o r c s i s t n n c e t o s t , Tho

p r i n c i p a l e l e n a n t t h a t an a s s e x ~ b l y must r a s i s t 3.3 hen t; t h e r e f o r e , furnacos a r e dosigned so t h a t tht3 o b j e c t t o s t o d forrns s w a l l of the f i r e box; and t h u s the h e a t i s dist?ibu.Led over the sm-face of

(7)

t h e assanibly, The dimensions o f 'ihe sa;nple t e s t e d cornpare :-~iP;h

b u i l d i n g u l i i t a such a 3 r ? a l l o r f l o o r pail~3.s and t h e samplo c a n bo sub j l s c k d t o vhz,'cever l o a d s i t riould ca.rarg i n a b u i l d i n g , The t o n p e r a t u r s i n t h e fwnaco 2s coli.trolleci t o ri? zigl-ood-cpon

h

r a t e o f r i s o du;-ing tho p o r l o d o r t;ic - L c s ~ , T h i s ~a1atioii::hLq

be tnoon tempora t u r o r i s e and 'G T r ~ s is knocn G S t h a t11:;n-temp:3~-3tur0

curve, which i s shoxn gr~aphicn31.ly -in

Fiz,

l o Thf s cur.crs x2..sp~wsents t h e condi-Lions h ~ h i c h nay o c c u r i n a s o v e r o f i r e b A n y specirrAcm9

t h e r e f o r e , l;ihich i s s u b j o c t o d t o tlma t e s t and a c h i e v e s a r a t f n g i n h o u r s o r minutes can, n l t h r e a s o n , ba e x p e c t e d t o las'c f o r t h o

sane l e n g t h of time u ~ d s r s i ~ i - l l a r f i P e c o n d i t i o n s i n a b u i l d i n g e

it; I s e v i d e n t t h a k an. assembly o f n!stool.fsls t h a t c a n viith-

s t a n d a s t a n d a r d f 2 r e - p a s i s t a n c o tozt f o r a p e r t o d of' t h q o o h o - a n i s s u b j s c t e d t o Inore ken% khca is a n a s s c n ~ i ~ l y . t h a t c a n c r i t h a t n n d a t e n t f o r orls h o ~ ~ , and t o p ~ o ( 2 u c o t h i s heat, nloj?e fr~e'S. i n c o n s u r t ~ s d ~ Tho f u e l used and hanco tht? h e e t producod I n ths t o s t s c a n bo

meaeurodo The an~o"e~~?,t o f Tusl used i;;h;sn szrzplo f a i l s g:lvos some idon of t h e ramouzzkof cor:~bustibles t h a t cou.ld bwn bofoaas t h a t

a s s o n b l y ~ r i E l fa51, I f o r e c t o d i n a buflclingR The n~3x.i; s b r ~ p n a s t o

determino tho rz~noxnt, of combust :'Lblcjs i n d-il"fc-se. *,,at t y p s o f b u f l d i n g s .

Vfileil t h i s w a s lmown i t 7 2 s ~ o s s i b B e t o recommand t h e dogl;ree of f i l r e

p e ~ i s t a a ~ o r e q u t r e d t o w i t h s t a n d a bmm-out of t h e c o n t a n t s of d i f l c r o n t b u r l d i n g a

F i r e Load

C ~ I L C E ~ ~ ~ :

Doctor Ingborg of t h e N a t f o n a l Bwoau o f -7

Stanciayeis i n \vnshing%ora was t h o p i o n e e r 1-7hooe s t u d f o s l e d t o measul*able r o l a t i o ~ z s : i i p s b ~ t n ; o e n th e f i r e r e s i s t a n c e detor.mlnod

i n t o s t s and t h e f i ~ s s o s i s t a n c o n e c e s s a r y i n b u i l d f n s s

( 4 ) ,

It was found t h a t t h e teiilpsratures a t t a f n o d a t c o r b i n t i n 3 i n t e r v a l s and t h e amount of f u e l bwrncd i n t h o s t a n d a r d f i r e r e s i s t a n c e t s s t s v e r a r o l s t a d , Froia r e p o a t o d t o s t s i t was d i s c o v o r e d t h a t f u e l

e q u i v a l e n t t o 10, 20, 30 and

35

pounds p e r square f o o t o f f l o o r a r e a w a s b n ~ n e d during t h e standard f i r s t e s t a t t h e end of 1, 2,

3 9 and

4

h o u r s , r o s p o c t i v o l y . T11us th3 f u u l uscd t o r c i s s t h o t e m p e r a t u r e t o 1700°F. a t t h o end of one hour r-ould be equivalent t o a f i r a l o a d o f 1 0 pounds of combustlblos p e r s q u a r e f o o t o f f l o o r a r e a , To a t t a i n a Somparatur~c o f 1850°F. a t t h e end of .two h o u r s , f u e l e q u i v a l e n t t o 20 pouado p e r squaro f o o t 1::ould be needed. By u s i n g 1 0 pounds p e r s q a a r e f o o t a s the value t o produce a f i r e intensity of 1700°F, a margin o f s a F o t y I s provided bocauso a c t u a l l y a n i n t o n s l t y o f 1700°F0 i s produced by b u r n i n g c o n b u s t i b l e s equl- v a l e n t t o 1 2 pounds p e r square f o o t o

It seems t r u e , a t l e a s t h y p o t h e t i c a l l y , t h ~ t if a b u i l d i n g c o n t a i n i n g a ten-poun6 f i r o l o a d was b u i l t of e l s m s n t s h a v i n z a

one-hour f i r e r a t i n g i t c o u l d j u s t s t a n d e bum-out nithsu,b c o l l a p s i n g . By t h e use of thg relationship b s t n s e n t h o c o i n i ~ u s t i b l s c o n t e n t s of

a b u i l d i n g and t h e f i r e r e s i s t a n c e %hero i s reasonable assuraEce t h a t any a s s ~ r r b l y of mater3.als r o c o i v i n g a 1-, 2-, o r 3-hour r a t i n g c o u l d w i t h s t a n d completo contonL bux~:~-c~.~t of a b u i l d i n g with a

lo-,

20-,

or 30-pcund f i r e l o a d r e s p o c t i v ~ l y ~ T h i s f i r e l o a d concopt p e r n i t s t h e a p p l i c a t i o n o f adequate, b u t n o t excos.':ivo Tire ~ a s i a t n n c e t o a b u i l d i n g vihen the solgkl'c of its com:lbuatible con'c;di~ti;s ~ u . 0 Imovrne

(8)

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l f q u i d s car1 be r e ~ z ~ d o d a s 11cicin.g a c a l o r i f i c TJ~,).~J.IB of do1:r'uls t h a t ,

o f wood, A fii20 i n a pa?-:nC s h o ; ~ 07 h a r d ~ r a ~ ~ a s t o r e can ba e;ipected

t o be nlors i n t e n s e t?lan 3-n e dpy sooils es'.i;,.lblfr,?%x6nnt. 111 tho

N a t i o n a l B u i l ~ r i i n s Codo t h c s o r l i f ' f o ~ o n o e s aye d e a l t v ~ i - t h in t119

occupanlzg classirica t5.02~

Frsn Yne for-going ClL~cussPo?~ i;'.1c? .terms ...---.- flro .-l o a d and --..a

--

f i r e

reu-j.otn91c.3 a r e c s t c b i i s h e d and f;hs r _{c i a}t _iomeilf 'uai;:ieen .tl~a t n o i s

-. .

-

'. r-

i i ~ . ~ i c a . ~ ~ ~ , In a:lditiol-a t o those t\r;lo ole,;\ci.lts f t 1 s necessary

_-

rocognfzo the sigil-i.f-icaraca o? s p s c a for full appreciation of t h o

f i:ra ~ e q u i r . ~ r ; l > n t - s of tha _{i;ia t i o n a l Ee1.12.cling}_Corf!.~, _{E x t o n o i v o} _s_tuclies

o n t3ori:;nl ~ ? a r l i a i ; i o n f i a o n :mrsz-lng b u l 3 . d i r r ~ n r-.9x8s prsrforz:..::d r e c s n t l y i n Gpoai; G r ~ i t a f n . Frfin .l;'nIs ~ a e - - ~ ~ - - . > L I ; , ~ C ~ 1 . k ~ ~ 3 s p o a n i b l a t o solas e x t e n t ,

to dcl;srinil:a uha -i; d l s.t=:nca bc.b.:or.::l 5u:il~ribrn:;s r ~ o u l d g i v e suftic i e r r t s a f e t y t o olla builclT-r$ f ~ o ! ; ~ i;i:l.:2ri:??l i - c C i a t i ~ r i fror~i nnuthe-ro Tho

intensity o f haat; :~.c?c.!iatsd f r o ~ i l 2 bl.x?ning bu-ildj.ng t o s n o t h e r b u i ld i r i g

depends. on :;ls:~y f a c t o r s :

(I) S'ill~doe n r e a on t h o e l o v a t i o ; ~ of a b u ~ l d l l z g ;

( i i ) Tsr:~p:>rztui*e a.l;t::fnod by t h a radj.stTl?g sul?.l?aco ( d i r e c t l y rcJ_,s-Lor"lo Sire l o a d of ths b u l l d i n g ) ;

(9)

For a clotailed a c c o ~ ~ i l t of therrilal r a d i a t i o n t h o r a a d e r i s r e f o r r u d t o t 7 ~ n v c s ~ t i . r p t i o ~ ~ s on E u i l d l n s P i ~ ~ o s "

(6).

I n t h i s same ps:i;phlot t a b l e s a r o pu.blishscl s:ll~ich i n d i c a t e tho p o l a t i o n -

shlp ol' f f r o r a d i a t i o n t o ho5.gh.b and leng'cii of' b ~ ~ i l d i r z g s , t l l o i r wind.olii oponfngr:, and t h o ~ . ~ s ' ~ c Y I c ~ b o t ~ c c n t l ~ ~ z i l c n By t110 uso o f

t h e z o .tab13 a npproxLr2ats calcu.la t i o n s f OF dis-banca s ba-*:son bulld.fns3 t o ovorcoms r a d i a t i o n affects can b e undo,,

Soljcpal a s s m p t i o n s a f f octing the r e l i a b i l i t y o f t k e s e t a b l e s h a d t o be mada when c o l l o c t i r ~ g t h e d a t a . Those f o l l o c :

( 5 ) That t h e temp3ra t u r o of t h e r a d i e t i n g f i l w i s 1, OOO°C, ( v a ~ i a t f o-13 fia0171 t h i s toiripora tu1.o waul-d

cause r:tc? j o r d i f f 0 1 ' 3 1 2 ~ ~ 3 ~ ~ C C U S U tho intensity of r a d i a t i o n I s d l r o c t l g p r o p o i a t i o n a l t o t h e fouxath pcnor of tho n b s o l u t o t c r n p o r a t u * ~ of tho r a d 1 a t i n . g s ~ ~ f n c e ); and

( i i ) That t h e ~ m - l s s i v i t y o f r a c i l a t f o n i s c o n s t a n t ; ( i i i ) !That h e a t i s b e i n s iac,dintod from a l l oponings

s i m u l t a n o o u s l g p ~

This l a s t assumption i s h i g h l y innpr-obable f o r a number of roaoort3, F f r s t l y , t h o f i r e rss5stanco of t h e c o n s t r u c t i o n which would s n c l o s o a f i r e w i t h i n sl;nll co,;lpslqti'll~nts would h i n d e r t o t a l

c o n f l a g r ~ t i o n . Secondly, t h 9 c ~ l i l ' u ~ . ~ t i b l e c o n t e n t s of t h e b u i l d i n g s aro n o t t h e sama t h r o u g h o u t and i t s i g n l t a b i l i - t y and r a t e o f

btrrnfn~g v?ould l i m l t f I r a cproad T~11rd7,yS f i r e f i g - h t i n g :-:ould have a s i g r ~ i f i c a n t e f f e c t on b o t h t1.1.o aovoi~it;y o f t h e fire and. t h o r a t s of i t s s p r o a d o !:!hen c o n s i d a r i n g thcse fac'r;a, i t i s apparent that t h e t a b l e s i n t h e publication :..rePo c o u ~ p i l o d froin d a t a c o l l e c t a d d u r i n g sxtrone f i r e condit-lol~a a c o l ~ d i t l o n s p r o b a b l y vrould n o t

becor~e s o extreme i n a.n nc'bual T i m nnd, therefma, t h e d i s t a n c s s r e q u i r e d f o r s a f e t y viould n o t be ao gPaa.te

2 , THE NATIONAL BUILDING CODE

The I h t i o n a l B u l l d l r ~ g Codo v a s f i r s t p u b l i s h e d i n 19/41 under t h e a u s p i c e s o f the Depart:.:c>nt o f Firmrice and t h e N a t i o n a l Resoarc11 Councfl A s b u i l d i n g t ~ c h n i q u o s changed and non n ; ~ t e r i a l s

were i n t r o d u c e d t h i s e a r l y e d i t i o n of t h o Ccdo b e c a m outnoded and i n nlany i n s t a n c e s v a s u m ~ s c o s s ~ ~ * I l ~ r o c - i ; r i c l l v s Tho f i r e rogu- l a t i o n s , p a r t i c u l a r l g . , d i d n o t m o t tho problems p r o s o n t e d 113 contcniporary b u t l d i n ~ s nor d i d thoy i n c o ~ p u ~ a t o t h o advances mado i n f i r e 0nzi~fie13inge \*~Tl~rl revision o f tho Codo com~snc;od i n 1?&8,

s t u d i e s viere rmde t o ~r,al:c po a s i b l o i t s i r f l p ~ ~ v ~ ~ i ~ ~ n t I t I-IEI s

iniporative t h a t t h e rovirocl code ahould n o t r a o s t r i c t rna t e r i a l s

and t y p e s of c o n s t r u c t i o n o l ~ d t11at i t s form ahould p e r a i t subsequent r e v i s i o n s o

(10)

An e n t - i r e l y new arrangem.ent f o r t h e Code was developed t r e a t i n g g e n e r a l requirements f i r s t , followgd by more d e t a i l e d and s p e c i f i c c l a u s e s , These a g a i n were divided, i n t o t h e g e n e r a l and s p e c i f i c wherever n e c e s s a r y , Commfttees and p a n e l s were

established t o prepare d r a f t s of t h e d i f f e r e n t p a r t s and s e c t i o n s . Unc1e.r t h e Use and Occupancy C o ~ r n i t t o e , f o u r paneln were s e t up

t o c o n s i d e r requirements f o r f i r e , h e a l t h , e x i t and l i v e loads. a. F i r e Regulations

The requ.irements o f t h e f i r e r e g u l a t i o n s

i n

t h e

1941

Code were c a r e f u l l y considered. by t h e F i r e Pailel and whenever proved

inadequate o r unnecessary by developments i n f i r e e n g i n e e r i n g , t h e y were r e v i s e d and improved, The f i r e l o a d concept was s t u d i e d and f i n a l l y accepted a s the b e s t method a v a i l a b l e f o r gauging t h e r e l a t i v e s e v e r i t y of f i r e i n d l f f e r o n t occupancies, and a s the c r i t e r i o n f o r determining t h e f i r e r e s i s t a n c e needed.

The c o n s i s t e n c y of f i r e r e g u l a t i o n s i n t h e National Building Code was achieved through t h e adoption of t h e f i r e l o a d of b u i l d i n g s a s t h e c r i t e r i o n f o r determining f i r e s a f e t y requirements. The

survey of t h e National Bureau of Standards

( 5 )

made it p o s s i b l e f o p t h e f i r s p a n e l t o c l a s s i f y occupancies o f b u i l d i n g s i n t o groups and d i v i s i o n s according t o s i m i l a r i t y of f u n c t i o n and e x t e n t o f hazard

-

t h i s c l a s s i f i c a t i o n i s fourla. i n s e c t i o n 3.2 of the Use and Occupancy S e c t i o n

-

and then t o t a b u l a t e t h e s e u s e s according t o t h e i r a p p r o p r i a t e f i r e l o a d s i n t a b l e

3.1.

T h i s f i r e l o a d c l a s s i f i c a t i o n forms t h e b a s i s f o r f u r t h e r r e g u l a t i o n s .

The primary f u n c t i o n s of a l l f i r e r e g u l a t i o n s a r e twotold: one, t o save l i v e s ; and the o t h e r t o prevent t h e spread o f f i r e . These a r e c l o s e l y r e l a t e d and one i s achieved only by adequate

coverage by the o t h e r . I n o r d e r t o save l i v e s s u r f i c i e n t f i r e e x P t s from a b u i l d i n g must be supplied. To c r e a t e a maximum o f l i f e s a f e t y f i r e s must be controll-ed, t h e i r spread r e t a r d e d , and the t r a n s f e r of h e a t , gas and smoke n u l l i f i e d . One method of c o n t r o l l i n g f i r e s i s by adequate f i r e s e p a r a t i o n s which ufould confine f i r e s w i t h i n a

l i m i t e d a r e a s e t t i n g up a b a r r i e r t o the t r a n s f e r of a l l hazards caused by a f i r e .

b. F i r e S e p a r a t i o n s Define+

I

The National Building Code, P a r t 2, d e f i n e s a s e p a r a t i o n a s follows:

" S e p a r a t i o n means a b a r r i e r a g a i n s t t h e spread of' f i r e between b u i l d i n g s o r p a r t s of b u i l d i n g s i n t h e form of f i r e - r e s i s t i v e c o n s t r u c t i o n , o r of c l e a r u n o b s t r u c t e d space a s

measured by t h e d i s t a n c e a c r o s s such space, o r of a combination of b o t h c o n s t r u c t i o n and space

."

This d e f i n i t i o n i s important. It establishes two k i n d s of separa- t i o n s

-

c o n s t r u c t i o n and space. It should a l s o be noted t h a t t h e s e a r e a l t e r n a t i v e s , s i n c e e i t h e r a c o n s t r u c t i o n o r a space s e p a r a t i o n

(11)

can be used between b u i l d i n g s . I t i s obvious t h a t c o n s t r u c t i o n s e p a r a t i o n s o n l y can be used when s e p a r a t i n g a r e a s w i t h i n a b u i l d i n g . Another a l t e r n a t i v e vrhich i s allowed f o r s e p a r a t i o n between b u i l d i n g s i s a combination of a c o n s t r u c t i o n s e p a r a t i o n w i t h a space s e p a r a t i o n , s o a r r a n g e d t h a t the sum of t h e p r o t e c t i o n provided i s e q u a l t o t h e grade o f s e p a r a t i o n r e q u i r e d i n t a b l e

3

a 7 r e f e r r e d t o i n a r t i c l e

3.4.5.1

of t h e Code.

The acceptance of space a s an e q u i v a l e n t t o c o n s t r u c t i o n i s a n o v e l t y of t h e new N a t i o n a l B u i l d i n g Code. The assumption made i s t h a t a s p e c i f i e d d i s t a n c e s e p a r a t i o n measured i n f e e t i s

t h e e q u i v a l e n t of a c o n s t r u c t i o n b a r r i e r having a s p e c i f i e d f i r e r e s i s t a n c e i n h o u r s (Fig. 2). Thus, a c c o r d i n g t o t h e Code t h e same

s a f e t y w i l l be provided behind ( f o r example) a one-hour f i r e r e s i s t i v e b a r r i e r a d j a c e n t t o the f i r e a s a t a 30-foot d i s t a n c e w i t h no b a r r i e r .

c

.

Grading and Requirements of Separa t i o n a

As p o i n t e d o u t p r e v i o u s l y t h e r e i s a r e l a t i o n s h i p between i n t e n s i t y of f i r e and f i r e r e s i s t a n c e and a l s o between I n t e n s i t y and i t s d i s s i p a t i o n w i t h d i s t a n c e . The committee was a b l e t o o b t a i n q u i t e r e l i a b l e d a t a on vrhich a p r a c t i c a l d e c i s i o n could be made and i t was agreed t h a t t h e e q u i v a l e n t should be :

D i s t a n c e Cons t r u c t l o n

30 f e e t e q u i v a l e n t t o

...

1 h o w f i r e r e s i s t a n c e

...

40

f e e t s q u i v a l e n t t o 2 h o u r s f i r e r e s i s t a n c e 50 f e e t e q u i v a l e n t t o

...

3

h o u r s f i r e r e s i s t a n c e

The v a l u e s shown i n t h e Code f o r s e p a r a t i o n by space a r e

h a l f t h e s e d i s t a n c e s because i n t h e c r i t i c a l case, i.e., two a d j a c e n t b u i l d i n g s w i t h no e x t e r i o r f i r e r e s i s t i v e w a l l s , t h e r e q u i r e d

s e p a r a t i o n i s o b t a i n e d i f one-half t h e r e q u i r e d d i s t a n c e i s provided by each b u i l d i n g , Therefore space s e p a r a t i o n s a r e c l a s s i f i e d i n t o

t h r e e grades: Grade _I_ D i s t a n c e Grade 1

...

15

f e e t

...

Grade 2 20 f e e t

...

Grade

3

25 f e e t

(12)

T11ese d i s t a n c e s a r e t o be nteasured from t h e p r o p e r t y l i n e t o t h e wa3.1 o f a b u l l d i n g , Thus space sopara-bions, l i k e c o n s t r u c t i o n

s e p a r a t i o n s , a r e Independent of t h e n n i g h b o u ~ f n g b u i l d i n g . The u s e of space s e p a r a t i o n s a l l o w 3 u n p r o t s c t a d openlngs t o be u s e d and t h e e x t e r i o r w a l l need not be f i r e r e s l s t i v s ( i t must be non- combustible when non-combustible c o n s t r u c t i o n I s u s e d ) , By space, a c l e a r space i s i n f e r r e d , w i t h o u t sheds o r r u b b i s h wllich would have a wicking a c t i o n be tween b u i l d i n g s ,

I t must be emphasized t h a t t h e s e v e l u o s a r e a practical compromise, They do not provide a g u a r a n t e e t h a t i n e v e r y c a s e f i r e s p r e a d m i l l bo ~ t o p p ~ d e Tho aim of t h s cornnittee vras t o s e t v a l u e s t h a t would p e a t l y improve t h a hazardous c o n d i t i o n s now

p e r m i t t e d by most b u i l d i n g by-lavrs, Good d e s i g n might d i c t a t e more f i r e r e s i s t a n c e I n sorne i n s t a n c e s , Tho code r e q u i r e m e n t was

c o n s f d e r e d t o be a s u i t a b l e minllmn requlrernent.

The arrangement of s e c t i o n

3.14.5

of t h o Code d e s e r v e s n o t e . There i s

3.4.5.1

which i s the p r i n c i p l e a r t i c l e and 3,j4*5.2 t o

3.1b.5.5

which d e a l w i t h t h e p r o t e c t i o n of openings i n c o n s t r u c t i o n s e p a r a t i o n s , Thoso a r t i c l e s ahould a l l be r e a d i f sopara t i o n s a r e t o be f u l l y understood. Tl~s s a a d s ~ f s a t t e n t i o n i s dravrn e s p e c t a l l y t o t h e second paragraph of 3aI~mSe2. Here i s t h e e x c e p t i o n a l c a s e when a c o n s t r u c t i o n s e p a r a t i o n i s p e r n i i t t e d w i t h u n p r o t e c t e d

openings. The use of u n p r o t o c t e d openings n o t exceeding 2 0 p e r c e n t of t h e w a l l a r e a i s allowed o n l y when t h e w a l l conforms t o t h e grade of c o n s t r u c t i o n s e p a r a t i o n r e q u i r e d and when t h e w a l l i s s e t back a d i s t a n c e t h a t i s h a l f t h e d i s t a n c e r e q u i r e d f o r t l ~ a t grade of space s e p a r a t i o n . Tharofore, i f a "Grade Gnon s e p a r a t i o n i s r e q u i r e d , t h e w a l l must have a one-hour f i r e r e s i s t a n c e and must be

s e t back from t h e p r o p e r t y l i n e a d i s t a n c e of 7 1/2 f e e t , With t h e s e q u a l i f i c a t i o n s t h e committee was w l l l i n g t o r e g a r d t h i s

s e p a r a t i o n a s e q u i v a l s n t t o a r e g u l a r c o n s t r u c t i o n s e p a r ~ t i o n * The advsntage of t h e compromise i s t h a t i t r e p r e s e n t s a form of cons-

t r u c t i o n which i s s t i l l v a r y common,

I t w i l l be n o t i c e d i n t a b l s 3.7 t h a t a c o n s t r u c t i o n

s e p a r a t i o n m a n s a complete b a r r i e r between two spaces, i n c l u d i n g c l o s u r e s and s h a f t s , t o p r o t e c t a l l openings. I t must be " f i r e - t i g h t t f a s the h u l l of a s h i p i s w a t e r - t i g h t , I t w i l I be observed, when s t u d y i n g t a b l o 3.7, t h a t the r e q u i r e d r a t i n g s f o r s e p a r a t i o n s , door, and s h a f t s , a r e n o t i d e n t i c a l , For example:

Grade 1 1 hour

...

3/4

hour

...*

3/4

hour

Doors a r e l e s s because i t was assumed u n l i k e l y t h a t f u r n i t u r e o r goods woul.3 be p i l e d a g a f n s t a door; hence, h i g h e r t e m p e r a t u r e on t h e unexposed f a c e of a door c o u l d be p e r m i t t e d c

(13)

S h a f t s a r e r e q u i r e d when openings a r e continuous from f l o o r t o f l o o r one above t h e o t h e r ( s t a i r w e l l , e l e v a t o r s h a f t s , a i r d u c t s , e t c . ) (Fig.

3 ) .

Tho f i r e requirements of s h a f t s a r e l e s s than those of c o n s t r u c t i o n s e p a r a t i o n s because a f i r e must f i r s t break i n t o the s h a f t and then break out t o g e t t o t h e next f l o o r . I n essence, t h e r e a r e two b a r r i e r s t o r e s i s t t h e f i r e and t h e r e f o r e , it was agresd t h a t t h e sum of the f i r e r e s i s t a n c e of

t h e b a r r i e r s should e q u a l t h e r e q u i r e d grade of s e p a r a t i o n ( F i g ,

4)

The openings of a s t a i r c a s e v~ould be a s i n Diagram A, Fig.

3.

The f i r e resistants of' the f l o o r constructLon would be of l i t t l e value; t h e staircase i s enclosod w i t h i n a s h a f t a s i n Diagram B, Fig.

3,

The f i r e r a s i s t a n c e of the s h a f t can be found from t a b l e 3.7, column

4

of t h e Code. The doors l e a d i n g t o the s t a i r c a s e must provide

f i r e r e s i s t a n c e e q u i v a l e n t t o t h a t r e q u i r e d i n column

3

of t a b l e 3.7. The s e p a r a t i o n of the s h a f t h e l p s t o i s o l a t e a f i r e on one f l o o r . F i r e r e s i s t i v e c l o s u r e s keep t h e s t a i r s h a f t f r e e from smokn, h e a t , gas, and flamo, thus providing s a f e egpess p a s t a burning s e c t i o n of a b u i l d i n g and a l s o s a f e a c c e s s f o r f i r o - f i g h t i n g pu-poses. Ducts: I n some c a s e s continuous openings a r e made i n i n t e r i o r a r u c t l o n s e p a r a t i o n s t o allow f o r the passage of ducts. It i s

i m p r a c t i c a l i n many i n s t a n c e s f o r such d u c t s t o be enclosed w i t h i n a f i r e r e s i s t i v e s h a f t , y e t i f they wore allotvod t o pass through the s e p a r a t i o n without any p r o t e c t f o n t h e n the s e p a r a t i o n v~ould be incomplete. I n o r d e r t h a t t h e s e p a r a t i o n and oponfngs i n a b u i l d i n g perform e f f i c i e n t l y when t h ~ b u i l d i n g i s b w n l n g t h e r e must be a n automatic f i r e damper w i t h i n the d u c t a t t h e s e p a r a t i o n ; thus, i f a f i r e should burn through a duct i t s spread from one s e p a r a t e d compartment t o another would be hindered. F i r e r e s i s t i v e c l o s u r e s and t h e types which a r e allowed a r e i n d i c a t e d i n a r t i c l o

3.4.5.5

of t h e Code.

: A r t i c l e

3.~.5.4

r e q u i r e s t h a t openings b u i l d i n g w i t h a f i r e load of over 2 0 pounds p e r square f o o t and r e q u i r e d s e p a r a t i o n s between f l o o r s , be

s e p a r a t e d by an apron o r s p a n d r e l w a l l n o t l e s s t h a n

3

f e e t i n h e i g h t ( ~ i g .

5).

T h i s i s a n ,example of applying the p r i n c i p l e of p r e v e n t i n s f i r e spread. a f i r e s e p a r a t i o n between f l o o r s i s r e q u i r e d i t i s a d v i s a b l e t o c o n s i d e r a d d i t i o n a l p r o t e c t i o n a t the edge. The f i r e could escape around the edge of the f l o o r s and

i n t o t h e f l o o r above. To overcome t h i s danger the Code r e q u i r e s a s p a n d r e l o r apron w a l l

.

Such a p r e c a u t i o n i s not r e q u i r e d i n a b u i l d i n g having a f i r e load of l e s s t h a n 20 pounds because the lower i n t e n s i t y of a p o s s i b l e f i r e would, i n most c a s e s , cause t h i s hazard t o be l e s s

s i g n i f i c a n t .

Having s t u d i e d s e c t i o n

3.J4.5

of t h e Code a t t e n t i o n should be n e x t d i r e c t e d t o s e c t i o n

3.4.6.

It i s important t o understand

(14)

3.111-.&

S e c t i o n 3.4.5 i s d e f i n i t i v e . I t should be r e a d i n c o n j u n c t i o n with the d e f i n i t i o n i n p a r t 2 and t h e e x p l a n a t o r y n o t e s on s e p a r a t i o n s , A l l t h e s e s e c t i o n s d e f i n e what s e p a r a t i o n s a r e , and c l a s s i f y them according t o grades.

3.l4.6.

S e c t i o n 3.1c.6 i s r e g u l a t o r y . This s e c t i o n e s t a b l i s h e s where s e p a r a t i o n s a r e r e q u i r e d be tween b u i l d i n g s and what grade

they must be, S e c t i o n s 3.4.7 t o 3.4.11 a r e s i m i l a r t o

3.4.6

e x c e p t t h a t they d e a l w i t h rooms and p a r t s of b u i l d i n g s i n s t e a d of t h e whole b u i l d i n g .

I t w i l l be observed t h a t throughout t h e requirements t h e grade of s e p a r a t i o n r e q u i r e d i s dependent on the f i r e load. This can be seen i n t h e d i r e c t r a f e r e n c e t o the f i r e l o a d i n s e c t i o n 3.4.6. I n t h e o t h e r s e c t i o n s t h e f i r e l o a d i s not mentioned, b u t t h e r e l a t i o n s h i p i s q u f t e evident. d . F i r e S e p a r a t i o n Be tween B u i l d i n p ~ I n s e c t i o n

3.4.6

a grade of s e p a r a t i o n r e l a t i v e t o t h e f i r e l o a d i s r e q u i r e d a s follows: F i r e Load c o n s t r u c t i o n o r space S e p a r a t i o n Grade 1 Grade 2 Grade

3

To determine t h e c o n s t r u c t i o n r e q u i r e d t o comply w i t h t h e s e f i r e s e p a r a t i o n requirements :

( i ) t n e f i r e load of the occupancy must be Icnown ( t a b l e

3.1);

( i i ) from the t a b l e i n 3.4.6 the r e q u i r e d ~ r a d e of s e p a r a t i o n can be found; and

( i i i ) t h e type o f c o n s t r u c t i o n t o comply w i t h t h i s ade of s e p a r a t i o n can be determined from

abr

t a e 3.7.

The following examples i l l u s t r a t e how t h e s e p a r a t i o n s can be uaed:

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EXAMPLE I CONSTRUCTION SEP. / - / + ? P R O P E R T Y L I N E 1. B u i l d i n g s A and B a r e two a d j a c e n t b u i l d i n g s . 2

.

B u i l d i n g A i s b u i l t t o t h e p r o p e r t y l i n e ; t h e r e f o r e a construction s e p a r a t i o n w i t h no openings must be used.

3.

The grade of tho con- s t r u c t i o n s a p a r a t i o n i s detsrmined by t h e f i r e l o a d o f b u i l d l n g A.

4.

Since a space s e p a r a t i o n (n) i s boing used f o r b u i l d i n g B t h e w a l l f a c i n g t h e p r o p e r t y l i n e may have u n l i m i t e d u n p r o t e c t e d openings, and t h e w a l l f i n i s h need n o t be f i r e r e s i s t i v e , provided, how- evep, t h a t a non-combustible f i n i s h i s used I n a non- combustible b u i l d i n g .

5.

The space s e p a r a t i o n

( n )

i s determined by the grade o f s e p a r a t i o n r e q u i r e d by t h e f i r e l o a d o f b u i l d i n g B e

EXAMPLE 11 1. Both b u i l d i n g s A and B use

space s e p a r a t i o n s 2. (n) and ( p ) a r e determined by t h e grade of s e p a r a t i o n r e q u i r e d by t h o f i r e l o a d s of t h e r e s p e c t i v e b u i l d i n g s ,

3.

The same r e g u l a t i o n s a p p l y to b u i l d i n g s A and B a s t o b u i l d i n g B i n Example I.

4.

The minimum d i s t a n c e which ( n

+

p ) could e q u a l i s 30 f e e t

-

i f b o t h A and B have PO-lb f i r e l o a d s t h e n each i s r e q u i r e d t o have an o f f - s e t of

1s

f e a t . Su.pposo b u i l d i n g A i s an o f f i c e w i t h a 10-pound f i r e l o a d and b u i l d i n g B i s a s t o r e w i t h a 20-pound f i r e load. I n Example I b u i l d i n g A tvould nsed a 1-hP f i r e w a l l and ( n ) f o r b u i l d i n g B would be 2Q f e e t , I n ExrampPe I1 ( p ) and (n) would bo

31s

a n d 2 0 f o o t

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EXAMPLE III 20°/0 UNPROTECTED WINDOW OPENINGS I N CONSTRUCTION SEPARATION

/

CONSTRUCTION SEP. 1, B u i l d i n g A r e q u i r e s openings i n t h e w a l l which do n o t exceed 20% of the w a l l a r e a . 4ssuming f i r e l o a d s a s b e f o r e , the s e p a r a t i o n r e q u i r e m e n t s a r e a s f o l l o w s : B u i l d i n g A E x t e r i o r w a l l s o f 2 h o u r s f f r e r e s i s t a n c e and a s i d e y a r d ( p ) of 7,

6"

(1/2 o f a Grade 1 s p a c e s e p a r a t i o n ) B u i l d i n g B The owner o f b u i l d i n g B e l e c t s t o u s e a Grade 1 c o n s t r u c t i o n s e p a r a t i o n p l u s a Grade 1 space sepnra t i o n t h u s a c h i e v i n g t h e r e q u i r e d t o t a l Grade 2 s e p a r a t i o n , e m S e p a r a t i o n by F i r e Walls The n e x t few p a r a g r a p h s d e s c r i b e a n o t h e r u s e o f s e p a r a t i o n s . T h i s i s a s e p a r a t i o n down t h e middle of a b u i l d i n g by a f i r e wall

( s e c t i o n

4.1.5)

(Fig.

6

1.

Here a new p r i n c i p l e must be i n t r o d u c e d , This i s t h e p r i n c i p l e t h a t c e r t a i n k i n d s o f b u i l d i n g s p r e s e n t t o o g r e a t a r i s k i f t h e y a r e b u i l t o f u n l i m i t e d s i z e . When a l a r g e b u i l d i n g i s r e q u i r e d , t h e r e f o r e , i t i s o f t e n p o s s i b l e t o b u i l d i t o n l y i f i t i s d i v i d e d by a f i r e w a l l g i v i n g t h e e f f e c t f o r f b e purposes of two s e p a r a t e b u i l d i n g s w i t h a c o n s t r u c t i o n s e p a r a t i o n between. A f i r e w a l l i s , i n f a c t , a c o n s t r u c t i o n s e p a r a t i o n but t h e r e q u f r e m e n t s f o r f i r e w a l l s have been developed from e x p e r i e n c e , w h i l e t h e c o n s t r u c - t i o n s e p a r a t i o n s a s d e f i n e d

i n

3.4.5

a r e t h e r e s u l t of t h e o r e t i c a l s t u d i e s , hence t h e r e a r e d i f f e r e n c e s i n d e t a l l be tween them.

I t i s e v i d e n t , t h e r e f o r e , t h a t h e i g h t and a r e a l i m i t a t i o n s and f i r e w a l l s a r e l i n k e d t o g e t h e r . H e i g h t s and a r e a s and typeq o f c o n s t r u c t i o n a r e a l s o l i n k e d . The r e l a t i o n s h i p be tween t h e s e t h r e e

s a f e t y measures i s a s f o l l o w s :

A l l b u i l d i n g s must be c l a s s i f i e d a c c o r d i n g t o t h e type o f c o n s t r u c t i o n . If t h e a r e a o r h e i g h t r e q u i r e d i s g r e a t e r t h a n t h a t a l l o w e d i n t a b l e

3.6

t h e n two c h o i c e s a r e open:

(17)

( i i ) he nlay p r e f e r t o choose anothel. type o f c o n s t r i l c t l o n 7r~hich p e r m i t s g-~peater h e i g h t o r 8P8a S e c t i o n

4.1.5

d e a l s w i t h t h s use of f i r e ~ q ~ a l l s a s f i r e s e p a r a t i o n s b e t m e n b u i l d i n g s o r p a r t s of b u i l d i n g s . Any par't of a b u i l d i n g separaked by a f i r e w a l l may be c o n s i d e r e d a

s e p a r a t e b u i l d i n g , and t h e a r e a s o produced must m a t a l l requ-irements of' f i r e e x i t s , s e p a r a t i o n s , e t c . A f i r e w a l l i s a p a r t y w a l l f o r it i s shared by two s e p a r a t e a r e a s of t h e same b u i l d i n g o r two d i f f e r e n t b u i l d i n g s . The gpndes OF f i r e w a l l s which must be used a r e :

Grade o r S e p a r a t i o n

F i r e Load f o r F i r e Wall

1 0 l b ~

...

Grade 2 2 0 l b 3

...

Grade

3

The grade of s e p a r a t i o n i s determined by u s i n g t h e maximum v a l u e of t h e f i r e l o a d s of e i t h e r of the a d j a c e n t occupancies.

I t h a s been shown how c o n s t r u c t i o n and space s e p a r a t i o n s c a n be used; however, r e f e r e n c e w a s made t o t h o f a c t t h a t f i r e w a l l s f o r p a r t y w a l l s ) could be used t o s e p a r a t e two b u i l d i n g s . The f o l l o w i n g example d e a l s w i t h t h i s problem:

1. If b u i l d i n g s A and B have

EXAMPLE I X 10-lb f i r e l o a d s t h e n t h e

f i r e w a l l must be a Grade 2 c o n s t r u c t i o n s e p a r a t i o n

-

i.9. 2-hour f i r e resistanca

2. If t h e f i r e l o a d of e i t h e r A o r B i s 20 l b s then the f i r e w a l l must

0

---

have a 3-hour r a t i n g . 7. I f t h e f i r e l o a d of e i t h e r / A o r B i s 30 l b s t h e n t h e f i ~ e w a l l must have a

4-

hour r a t i n g .

(18)

EXAMPLE Y 1. If e a c h i n d i v i d u a l a r e a A and B were t o be b u i l t w i t h i n d i v i d u a l con- s t r u c t i o n s e p a r a t i o n s a t th5 p r o p e r t y l i n e , (Example V ) , t h e r e g u l a t i o n s p e r - t a i n i n g t o c o n s t r u c t i o n s e p a r a t i o n s tvould be valid, CONSTRUCTION SEP. 2, If A and B rvere b o t h 1 0

l b s t h e n t h e c o n s t r u c t i o n s e p a r a t i o n f o r e a c h would be 1 h o u r a d d i n g t o 2 h o u r s t o g e t h e r

.

3.

If A had a 1 0 - l b f i r e l o a d and B had a 2 0 - l b f i r e l o a d t h e n the t o t a l f i r e s e p a r a t i o n =

3

h o u r s .

4.

If A had a 1 0 - l b f i r e l o n d and B had a 30-lb f i r e l o n d t h e n t h e sun of t h e s e p a r a t i o n would

be

4

h o u r s .

5.

NeBo A t t h i s p o i n t t h e p a r a l l e l e n d s , b e c a u s e i f A had a 20-lb f i r e l o z n d B had a 20-lb f i r e l o a d t h e n t h e c o n s t r u c t i o n s e p a r a t i o n would e q u a l

4

h o u r s . If A had a 20-lb f i r e l o n d and B had a 30-lb f i r e l o a d t h e n t h e c o n s t r u c - t i o n s e p a r a t i o n s would e q u a l

5

h o u r s . If b o t h A and B had 30-lb f i r e l o a d s t h e n t h e c o n s t r u c t i o n s e p a r a t i o n s would e q u a l

6

houru. I t i s e v i d e n t t h a t when i n d i v i d u a l f i r e s e p a r a t i o n s a r e b u i l t by t h e

a d j o i n i n g a r e a s t h e f i r e p r o t e c t i o n i s increased c o n s i d e r a b l y , T h i s may be j u s t i f i e d by t h e f a c t t h a t t h e occupancy of t h e a d j a c e n t

b u i l d i n g and t h e h a z a r d s it would p r e s e n t a r e n o t a l w a y s knowno \ h e n f i r e w a l l s a r e used, a number o f c o n d i t i o n s must be met which a r e n o t r e q u i r e d when u s i n g c o n s t r u c t 5 o n s e p a r a t i o n s .

When two a r e a s a r e b o i n g s e p a r a t e d bg a f i r e v ~ a l l , a p a r a p e t

( 3

f e e t i n most c a s e s ,

6

i n c h a s between d w e l l i n g units) must be u s e d s o t h a t t h e r e w i l l be a complete b r a a k i n t h e r o o f c o n s t r u c t i o n . A c o n s t r u c t i o n s e p a r a t i o n d o e s n o t r e q u i r e a p a r a p e t , I n b o t h c a s e s f i r e s p r e a d t h r o u g h r o o f c o n s t r u c t i o n would be h i n d e r e d , b u t w i t h t h e f i r e 1m11 t h i s e f f e c t would be more p o s i t i v e . I n b u i l d i n g s o f combustible c o n s t r u c t i o n a f i r e must be s u p p o r t e d on t h e f o u n d a t i o n and c o n t i n ~ i o u s from t h e f o u n d a t i o n t o t h e p a r a p e t , Vhen t h e c o n s t r u c t i o n o f t h e b u i l d i n g i s o f non-combustibla m a t e r i a l s t h e n t h e f i r e w a l l may be s u p p o r t s d by t h a s t r u c t u r a l frazns p r o v i d e d t h e f i r e r e s i s t a n c e of t h e s t r u c t u r a l frame i s a s g r e a t a s , o r g r e a t e r t h a n , t h a t of tho f i r a v m l l . A s nlantionad, t h e f i r e w a l l must be c o n t i n u o u s . O f f s e - t s a t f l o o r l e v e l s a r e p e r m i t t e d b u t t h e c o n s t r u c t i o n of the o f f s e t f l o o r s and w a l l s must h s v e f i r e r e s i s t s n c e e q u a l t o t h a t o f t h e f i r e m a l l ( F i g . 7).

(19)

Other r e q u i r e m e n t s of f i r a w a l l s a r e s t a t e d i n a r t i c l e s

4.1a5.3

and

401.5.4

of t h e TJBC.

f .

-

F i r e S e p a r a t i o n IEIithili B u i 1 d f n . c ~ ~

Although i t i s p o s s i b l e t o use f i r a s e p a r a t i o n s anywhere i n s i d e b u i l d i n e s ~ i h e n , i n t h o o p i n i o n o f t h e ownor o r a r c h i t e c t , t h e y a p p e a r t o bo u s e f u l , t h e N a t i o n a l B u i l d i n g Code

--

r e q u i r e s

----

f i r e s e p a r a t i o n s i n c e r t a i n p l a c e s a s a b a s i c minimurn s t a n d a r d . The g r e a t e s t c o n t r i b u t i o n t o i n t e r n a l f i r e s a f e t y i s ths s e p a r a t i o n o r i s o l a t i o n o f one s t o r y from a n o t h e r t o combat s p r e a d o f f i r e

v e r t i c a l l y , and t h e p r o v i s i o n o f s a f e means o f e s c a p e by t h e

e n c l o s u r e and s e p a r a t i o n o f u n i t s . F i r e s o p a r a t i o n s a r e a l s o u s e d t o s e p a r a t e major o c c u p a n c i e s and s p e c i a l h a z a r d s a s i n d i c a t e d i n t h e f o l l o w i n g paragpaphs, e x p l a i n e d i n t h e o r d e r i n which t h e y a p p e a r i n t h e Code.

Major Occu a n c i e s : Whon t h e r e a r e two o r more major o c c u p a n c i e s i n u i d ng t h e y must be s e p a r a t e d a s s t a t e d i n s e c t i o n

3.4.7 bLrr

and t a b l e

3.8

(Fig.

8 ) .

If one of the major o c c u p a n c i e s r e q u i r e s a Grade Ons s e p a r a t i o n and t h o otllor r e q u i r e s a Gracto Tv1o s e p a r a t i o n , t h e g r a d e of s e p a r a t i o n must be t h e g r e a t o r o f t h e two, i n t h i s c a s e Grade Two. Thus, i f a m e r c a n t i l e and a r e s i d e n t i a l occupancy were t o be t h e major o c c u p a n c i e s o f a b u i l d i n g t h e grado o f s e p a r a t i o n r e q u i r e d a c c o r d i n g t o s e c t i o n

3.4.7

and t a b l e 3.8 would be a Grade Two s e p a r a t i o n .

E x i t s : The s e p a r a t i o n of e x i t s from t h e f l o o r

areaE

o f a b u l l d i n g

7

i s one o f t h e most irriportant l i f e s a f e t y f a c t o r s i n c o r p o r n t o d i n t o any b u i l d i n g ( s e c t i o n

3.4.8).

A numerous s u p p l y o f e x i t s i s

commendable; however, i f t h e s e a r e f u l l of fl-ames, srioke and g a s e s d u r i n g a f i r e t h e y a r o o f no use t o t h e o c c u p a n t s o f t h e b u l l d i n g . Because of t h i s , e a c h e x i t munt be s e p a r a t e d froni t h e r u s t of t h o b u i l d i n g so t h a t it i s a contLnuous and independent v e r 2 ; f c a l member, and i t s s e p a r a t i o n must be supported. from tihe ground oo tha.t t h e c o l l a p s e o f any f l o o r w i l l n o t endanger a n e x i t n o r t h o p e o p l e u s i n g i t d u r i n g a f i r e . T h e s e p a r a t i o n r e q u i r e n l e n t s o f e x i t s a c c o r d i n g t o s e c t i o n

3.4..8

a r e :

F i r e Load. of Occupancy Grade o f Sepnra t i o n 1 0

-

20 l b s

...,...4

Grade 1 g r e a t e r t h a n 30 l b s

.

,

.

,

. . .

,

.

. .

.@ Grade 2 T h e s e p a r a t i o n i s r e q u i r e d . o n l y between t h e " f l o o r a r e a s ' ' of t h e b u i l d i n g and t h e e x i t ( F i g , 9 ) ; t h e r e f o r e , i f t h e e x i t s h o u l d be on a n e x t e r i o r w a l l f a c i n g a s t r e e t , t h e n t h e s j d e s o f the e x i t f a c i n g t h e s t r e o t a r e n o t r e q u i r e d t o be f i r e r e s i s , t a n k ( a s p r e v i o u s l y s t a t e d , t h e s e vralls m ~ l s t bo non-ccrr~bustiblo i n non-ccnbus t i b l e

c o n s t r u c t i o n ) . F i r e s e p a r a t i o n s a r e requixwd f o r o v e r y oxit, Nunber of e x i t s , s i z s e t c . a r e determined i n Use and O c c u p a ~ c y SectLon 3.20.

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S e c l a l Occupancx: Many s p e c i a l purpose rooms, such a s k i t c h e n s and &%ce rooms, p r e s e n t f i r e h a z a r d s t o buildings. To ovorcome t h e

h a z a r d s which tvould a r i s e from t h e occupancy of t h e s e roonis, s p o c i a l r e g u l n t i o n s werg established whlch a r o o f f s c t i v c j r e g a r d l e s s of tho use of t h o b u i l d i n g and of any ot'nor f i r e r o t s c t i o n requirements. These r e g u l a t i o n s a r e s t a t e d in. s e c t i o n

3,

f)

!.,I0 o f t h e Codo.

A t t i c , Crawl and Duct Spaces.: b1Ihen buildi.ngs a r e s e p a r a t e d by c o n s t r u c t i o n separa tion.s, e l l a t t i c , c r a w l and d u c t s p a c e s n ~ u s t a l s o be s e p a r a t e d ( F i g ,

l o ) ,

If t h i s i s not dons t h e n t h e f i r e c o u l d s p r e a d by K a y o f the a t t i c , c r a n l , o r d u c t space from one e n c l o s e d a r e a t o artother. Section

?

,4..11

d e a l s w i t h t h e s e r e q u i r e - ments ( r e f e r d i r e c t l y t o s e c t i o n 3,+.5,3 i n t h e c a s e of d u c t s n o t e n c l o s e d i n f i r e r e s i s t i v e s h a f t s ) , CONCLUSION I n c o n c l u s i o n , and a f t e r t h c c o n s i d e r a t i o r z o f so many d e t a i l s i t i s n e l l t o romembor t h e g e n e r a l p r i n c l p l o t h a t r e g u l a t i o n s a r e f o r t h e purFose o f e n s u r i n g a minbium s t a n d a r d of s a f e t y , T h i s i s n o t alwsgs t o o e a s y t o d e f i n e .

Tlio minimum i s ~ i l v ~ a y s s e t by agreement based on e x p e r t o p l n i o n on t h o degree o f s a f e t y which t h e p u b l i c w i l l t o l e r a t e . From t h i s p o i n t onvard t e c h n i c a l information, r e s u l t i n g from r e s e a r c h o r some form of m e t h o d i c a l i n a a s t i g a t l o n c a n o f t o n show

h01if tho d e s i r e d s a f e t y measmaes c a n be a c h i e v e d w i t h l e s s i n t e r f e r e n c e o r r e s t r l . c t i o n or, t h e a c t i o n s of t h o s e who builcl, Such inly)~%oved r e g u l a t i o n s may r e s u l t ; i n b u i l d i n g economies, op a more c o n s i s t e n t

s t a n d a r d of s a f c t y , o r b o t h , Bhichover i s t h e c a s e i t sh.ould be v~elcomed because e f f l c ioney arid s a f e t y go hand-in-hand.

Tho new r e g u l a t i o n s i n t h e N a t i o n a l B u i l d i n g Code a r e based on 5 n f o r n a t i o n gained from r e s a a r c h , Blthougli not p o r f o c t t h e y have been acclaimed by mgny a s a c o n s i d c r a b l o improvement o v e r otlzor

oontomporary r e g u l a t i o n s , The l a c k of u n d e r s t a n d i n g ~ i h i c h r e s u l t s

from t h e i r nsnnoss i s a l i m i t i n g f a c t o r i n t h e i r use, It i s hoped t h a t t h i s papor w i l l h e l p m a t e r i a l l y t o c o r r e c t t h i s coriditione

The a u t h o r s of t h e s e r e g u l a t i o n s , while d e f e n d i n g them a r e , a t t h e same time, t h e i r most s e v e r e c r i t i c s . Devsloprr,ejnt o f improved r e g u l a t i o n s d i d n o t s t o p w i t h t h e p r i n t i n g of the 1953 B a t i o n a l

E u i l d i n g Code but h a s continued, and impror~ermnts ~ i 1 1 be anriounced fron; time-to-time, Toclay, w i t h nev: technology niuch o f t h e o l d method of c o n t r o l f o r s a f e t y no l o n g e r a p p l i e s , Unless b u i l d i n g r e g u l a t i o n n advance w i t h t h e t i m e s t h e y w i l l be put a s i d o o r overlooked a s a

measure f o r s a f e t y , I t i s t o be hoped t h a t i f b u i l d i n g r e g u l a t i o n s a r e e v e r l e s s used t h a n t h e y a m today i t m - i l l be because t h e y a r e l e s s needed and n o t because t h e y have becoma Tntidequate f o r t h e i r t a s k ,

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Roferencoa

1. E i ~ d ,

S.L.

and S.J. Docking. Fire in buildings. Editors, Adam and Charles Blaclr. London 19149. pa

30,

2. National Fire Prevontion Associationo Handbook of fire protection, 11th edit;ion,

1954.

p,53,

3.

Standard methods of f i r e tests of building construction and materials. A.S

.T.IVle

Designa tion:

E119-55,

A.S .T.M. Standards Part

4,

1955.

p.

1177-1187,,

4.

Bird,

E.L.

and S.J. Docking. Fire in buildings. Editors, Adam and Charles Black, London

1949.

p e

90,

5.

Ingberg, S.B. Conlbustible contents in buildings. U.3. National Bureau of Standards, Wash., E.M,Se

149,

July

19570

6.

Investigations on building fires. National Euilding Studies: Part 111 Radiation from Buildfng Fires, Tech, Paper No.

5,

London, J m e

1950.

24

p r

Wood, B.L. Fire protection through modern building codes,

(A

correlation of factual data and regulatory procedure. ) American Iron and Steel Institute, New York, N.Y.,

1950.

156

P.

U . S . National Bureau of Standards. Fire resistance classification

of buildin constructions. B.M.S. Report

92,

Washington, October

19&.

President 1 s Conference o n Fire Prevent ion. Report of the committee^,

o n building construction, operation and protection. Vfashington Iday

1947r

30

P.

British Standards Institution. Fire tests o n building materials and structures, B.S.

476:

1953.

24

p.

Great Britain, Ministry of Works. .Po~t-~tJar Building Studies No

,

20. Fire grading of buildings. Part 1:General principles and

structural precautions by a joint committee of the Building Research Board, D.S. I.R., and Fire Offices1 Committee.

(22)

FIGURE I

T I M E TEMPERATURE CURVE

FIGURE 2

SKETCH SHOWING SPACE AS AN EQUIVALENT

(23)

D l A G A

FIGURE 3

D l A G B

DIAGRAMS SHOW HOW SHAFTS ARE REQUIRED FOR

CONTINUOUS FLOOR TO FLOOR OPENINGS ( S T A I R C A S E

)

FIGURE 4

SHAFT ACTS AS TWO BARRIERS P E R M I T T I N G LOWER

F l k E RESISTANCE THAN THAT REQUIRED FOR FLOORS

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A P R O N W A L L T O

1

S E P A R A T E F L O O R

A R E A S ( A T L E A S T 3' 0 " )

FIGURE 5

SKETCHES SHOWING HOW APRON AND SPANDREL WALLS PREVENT F l R E SPREAD FROM FLOOR TO FLOOR

SKETCH OF F l R E WALL SHOWING ONE BUILDING D I V I D E D I N TWO SO THAT AREAS ON EACH SIDE W I L L NOT E X C E E D CODE R E Q U I R E M E N T S

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FlRE WALL

OFFSET FLOORS AND WALL W I T H F l R E RESISTANCE EQUAL TO THAT OF THE F l R E WALL F I G U R E 7 S K E T C H O F O F F S E T F L O O R S AND W A L L F I G U R E 8 C O N S T R U C T I O N S E P A R A T I O N O F T W O M A J O R O C C U P A N C I E S

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CONSTRUCTION SEP. OF E X I T ( A C C O R D I N CLOSURES W I T H F I R E R E S I S T A N C E ACCORDING T O C0LUP;IN 3 T A B L E 3 . 7