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Roof Design and Roofing Terminology
Ser THl N21t2
no. 130
c . 2
BI,DGNAT IONAL RESEARCH COI'NCIL
CANAD4.
DIVISION OF BUILDII.iTG RESEARCH
ROOT' DESIGN AND ROOF'ING TERMINOLOGY
B Y
M. C. BAI(ER
A N A L Y Z E D
OF THE
DIVISION OF BUILDING RESEARCH T E C H N I C A L P A P E R N O . 1 3 0
O T T A W A
P R E F A C E
T h e r n a t e r i a l n o w p r e s e n t e d w a s p r e p a r e d a s a c o n t r i b u t i o n b y t h e D i v i s i o n t o a S e m i n a r o n B u i I t - U p R o o f i n g s p o n s o r e d b y t h e
Canadian Arrny. It is now issued as a publication to facilitate the provision of a large nurnber of copies for serninar use and to rnake it available in its present forrn to others who rnay find it of value.
T h e a u t h o r , a r e s e a r c h o f f i c e r w i t h t h e D i w i s i o n , h o l d s d e g r e e s i n e n g i n e e r i n g a n d a r c h i t e c t u r e a n d i s e n g a g e d o n s t u d i e s o f r o o f s a n d r o o f c o v e r i n g s . Ottawa J a n u a r y l 9 6 2 N . B . H u t c h e o n , A s s i s t a n t D i r e c t o r .
ROOT' DESIGN AND R"OOFING TER1\{{T\{OI,0GY
b y M . C . B a k e r
T h i s p a p e r w a s p r e s e n t e d a t a canadian Arrny Buitt-up Roofing serninar held in ottawa on october zlth and, z6th, 196I. Thd serninar was organized by the Asphalt Roofing Technical Gornmittee of the canadian Asphalt Roofing Industry, with participation also by the canadian Rsof,ing contractorsr Association. The paper was prepared as an i'ertroductory talk to define in a general way the whole roofing field and infroduce subjects discussed aL greater length and in d e t a i l b y o t h e r s .
ROOF DESIGN
A roof is the top covering of a buirding, and basically rnay b e c o n s i d e r e d t o c o n s i s t o f t w o units: a structural roof deck, and a roofing systern that covers the deck to keep out the elernents. It rnay be further broken down into five component parts:
(I) The ceiling or part of the roof visible from inside the building. In rnany cases it rnay be the underside of the roof deck, but often i t c o n s i s t s o f s e p a r a t e construction to conceal mechanical services. It rnay also in sorne designs carry the insulation, in which case the space between it and the roof frarne rnay be ventilated.
(Zl The roof deck placed on the structural frarning of the buitding to carry the load of the roof construction and other Ioads that rnay be applied to it.
(3) A foundation layer which is sornetirnes necessary to provide a suitable surface on which to lay roofing and,/or to produce a suitable p i t c h o r s l o p e o n t h e roof for drainage purposes.
(41 Therrnal insulation to protect against extrernes of heat and cold. This is cornrnonly located above the deck, but rnay sornetirnes be c a r r i e d b y t h e c e i l i n g ( a s i n d i c a t e d in item I above. )
( 5 ) R o o f i n g o r r o o f - c o v e r i n g , w h i c h p r o t e c t s t h e w h o l e c o n s t r u c t i o n against the elernents, and particularly against moisture penetration.
^ z
-T h e c e i l i n g i s r r s u a l l y a n a r c h j t e c t u r a l d e s i g n c o n s i d e r a t i o n a n d d o e s n o t e n t e r i n t o t h e s c o p e o f t h i s s e r n i n a r . R o o f s a r e c o n s t r u c t e d i n a v a r i e t y o f s h a p e s s u c h a s g a b l e , s h e d o r I e a n - t o , h i p , g a r n b r e l , r n a n s a r d , f l a t , s a w t o o t h a n d s p e c i a l w i d e s p a n d e s i g n s ( F i g . i ) . T h e s l o p e o f a r o o f s u r f a c e i s g e n e r a l l y ' r e f e r r e d t o a s t h e p i t c h o f t h e r o o f a n d i s e x p r e s s e d i n t e r r n s o f t h e f r a c t i o n a l r a t i o b e t w e e n t h e r i s e a n d t h e h o r i z o n t a l s p a n . I f a r o o f i s d e a d l e v e l t h e r e i s n o r i s e ; i f a g a b l e r o o f s p a n n i n g a b u i l d i n g Z O . - l t w i d e h a s r a f t e r s t i e d t o g e t h e r a t t h e r i d g e a t a n e l e v a t i o n o f l 0 f t a b o v e t h e e a v e s , t h e p i t c h i s I 0 / Z O o r I / Z p i t c h ( F i g . Z l . T h i s r n a y b e e x p r e s s e d a l s o a s a r a t i o o f r i s e t o r u n f o r l o w e r s l o p e d r o o f s , u s u a l l y a s i n c h e s o f r i s e p e r f o o t o f r u n , b e i n g I Z i n I Z f o r h a l f p i t c h , r v h i c h o f c o u r s e i s a n a n g l e o f . 4 5 d e g t o t h e h o r i z o n t a l . A 4 i n I 2 r o o f r n a k e s a n a n g l e o f I B I f 2 d e g w i t h t h e h o r i z o n t a l . O n f l a t r o o f s w i t h s l o p e s l e s s t h a n I i n l 2 i t i s n e c e s s a r y t o s t a t e s l o p e t h u s , a s l / 4 i n . p e r f o o t , o r I i n 4 8 . T h e t e r r n f l a t r o o f i s g e n e r a l l y a p p l i e d t o r o o f s h a v i n g l o w s l o p e s o r p i t c h e s t o t h e r o o f d r a i n s ( F i g . 3 ) . F r a r n i n g r n a t e r i a l s f i ) a y b e o f w o o d , s t e e l o r c o n c r e t e , a n d a s u i t a b l e c h o i c e i s u s u a l l y b a s e d o n a t h o r o u g h a n a l y s i s o f t h e e n t i r e r o o f a s s e r n b l y o n a n a r c h i t e c t u r a l , s t r u c t u r a l a n d e c o n o r n i c b a s i s . T h e s t r u c t u r a l a s s e r n b l y c o n s i s t s o f f r a r n i n g r n e r n b e r s s u c h a s b e a r n s , r a f t e r s a n d p u r l i n s w i t h a n i n f i l l b e t w e e n r n a i n s t r u c t u r a l r n e r n b e r s t o f o r r n a r o o f d e c k .Up to World War I I two types of deck predorninated - wood a n d c a s t - i n - p l a c e c o n c r e t e . T h e l a r g e a r n o u n t o f b u i l d i n g a f t e r t h e W a r a n d t h e t r e n d t o w a r d o n e - s t o r y b u i l d i n g s g r e a t l y i n c r e a s e d t h e r o o f a n d roofing rnarket, however, and stirnulated the developrnent of an increasing nurnber of different roof decks. There are about forty tytres of deck now i n u s e , b u t t h e s e c a n b e d i v i d e d i n t o s i : < r n a j o r c l a s s i f i c a t i o n s : ( I ) w o o d , ( Z l s t e e l , ' ( 3 ) c a s t - i n - p l a c e c o n c r e t e , ( 4 ) p o u r e d - i n - p l a c e r n a t e r i a l s s u c h a s g y p s u r n , p e r l i t e , v e r r n i c u l i t e o r o t h e r l i g h t w e i g h t c o n c r e t e s , ( 5 ) n a i l a b l e p r e c a s t u n i t s , ( 6 ) n o n - n a i l a b l e p r e c a s t u n i t s . A b r o a d d i v i s i o n o f a l l d e c k s c a n b e r n a d e w i t h r e f e r e n c e t o f i x i n g t h e r o o f c o v e r i n g s : d e c k s t o w h i c h t h e r o o f c o v e r i n g c a n b e f i x e d
- J
l b y n a i l i n g , a n d d e c k s t o w h i c h t h e r o o f c o v e r i n g s h a v e t o b e ceprelted. S o r n e o f t h e d e c k s h a v e i n h e r e n t i n s u l a t i o n v a l u e , a n d each of the rnaJor c l a s s i f i c a t i o n s r e q u i r e s s p e c i a l c o n s i d e r a t i o n i n b h e c h o i c e a n d a p p l i c a t i o l o f r o o f c o v e r i n g .
T h e r o o f c o v e r i n g i s p r o b a b l y t h e most irnportant elernent in a b u i l d i n g . I t p r o t e c t s t h e s t r u c t u r e i t s e l . f a n d p r o v i d e s for the comfort o f t h e b u i l d i n g o c c u p a n t s a s well as the protecbion of valuable property. At the sarne tirne it rnust withstand a wide variety of clirnatic conditiorrs -w i n d , r a i n , h a i l , s n o -w , i c e , extrernes internperature, a n d a n y c o r n b i r r . a t i o n of these elemefrts.
R O O F I N G
W a t e r p r o o f i n g i s t h e r n o s t i r n p o r t a n t p a r t of the roofing cover. I t p r e v e n t s w a t e r f r o m e n t e r i n g i n t o the roof construction, but cannot p e r f o r m p r o p e r l y unless it is considered in relation to all the other c o m P o n e n t p a r t s o f t h e r o o f . While there is an arnazing variety of roof c o v e r i n g s a v a i l a b l e , t h e r e a r e two main groups:
( l ) r n u l t i p l e u n i t r o o f c o v e r i n g s , ( ? l s i n g l e u n i t r o o f c o v e r i n g s .
Multiple unit roof coverings such as shingles and tile depend l a r g e l y u p o n t h e i r w a t e r s h e d d i n g qualities, and the degree of effectiveness g e n e r a l l y d e p e n d s o n t h e s l o p e of the roof and the area of each unit
e x p o s e d t o t h e w e a t h e r .
Single unit roof coverings rnay also be cornposed of a nurnber o f u n i t s , b u t t h e f i n i s h e d r o o f i n g is a single-unit, flexible, waterproofed, custorrr-built rnernbrane that depends on its waterproofing qualities to k e e p o u t t h e w a t e r t h a t collects before it drains slowly to drainage otrtleLs. T h i s i s t h e b u i l t - u p r o o f i n g ( 8 . U. R. ) that is the rnain consideration of t h i s s e r n i n a r , - s o c a l l e d b e c a u s e it consists of plies or layers of roofing f e l t b o n d e d t o g e t h e r o n site with biturnen, with or without a protective s u r f a c e c o a t i n g t o g i v e i t i n c r e a s e d resistance and reduce the harrnful e f f e c t s o f s u n l i g h t o n t h e r n a t e r i a l s . T h i s s e r n i n a r w i l l c o n f i n e i t s e l f to hot-application built-up roofing in which hot biturnen is used to cernent t h e f e l t s .
T h r e e t y p e s o f b u i l t - u p r o o f i n g w i l t b e c o n s i d e r e d : ( I ) t a r a n d g r a v e l ,
( 2 1 a s p h a l t a n d g r a v e l ,
4
-M ATERIALS
T h e r e i s a l a c k o f a g r e e m e n t b e t w e e n a r c h i t e c t s , b u i l d e r s , r o o f i n g c o n t r a c t o r s , a n d p r o p e r t y o w n e r s , a s w e l l a s b e t w e e n c o u n t r i e s on roofing terrninology. This paper atternpts to clarify and arnplify the definitions of biturninous rnaterials agreed to by the Asphalt Roofing Technical Cornrnittee. (See Appendix A, Glossary of Roofing Terrns. )
Biturnen is a generic terrn describing any native mixture of heavy hydrocarbons in viscous or solid forrn, and in the roofing industry r n a y b e u s e d t o i n d i c a t e e i t h e r a s p h a l t o r c o a l - t a r p i t c h . I n t h e s o l i d
dtate these rnaterials appear alike, but the characteristics are sornewhat different.
Most of the asphalt used in Canada as an irnpregnating and waterproofing agent in asphalt roofing products and built-up roofing is the residue of petroleum Cistillation, with solne refinernent to achieve desirable properties and a range of softening points. Asphalt in its natural state is also found in sorne parts of the world in large solid deposits called l a k e s .
Coal-tar pitch is a bittrrninous rnaterial produced by distilling c r u d e t a r r e s i d u e d e r i v e d f r o r n t h e c o k i n g o f c o a l . I t i s c o n s i d e r e d t o h a v e e x c e l l e n t s e l f - h e a l i n g p r o p e r t i e s , b u t c a n o n l y b e u s e d o n v e r y l o w slopes frorn dead flat to approxirnately I in. per foot. Low rnelt point asphalts are used on lower slopes, and higher rnelt point asphalts can be used on rnuch steeper slopes, and consequently asphalt has a rnuch wider range of application.
When biturnen is heated for use in constructing a built-up r o o f , i t i s o f t e n r e f e r r e d t o a s h o t - s t u f f . P r o p e r h e a t i n g i s e x t r e r n e l y i r n p o r t a n t , s i n c e o v e r h e a t i n g c a n c o r n p l e t e l y d e s t r o y t h e d e s i r a b l e properties obtained by rigid rnanufacturing control. Proper adhesion
is achieved with coal-tar pitch at application ternperatures ranging frorn 3 2 5 t o 3 7 5 " F a n d w i t h a s p h a l t f r o r n 4 0 0 t o 4 3 0 ' F . T h e r n a t e r i a l s s h o u l d n e v e r b e h e a t e d b e y o n d 4 0 0 " F f o r p i t c h a n d 4 5 0 " F f o r a s p h a l t . Be1ow the rninirnurn stated the biturnen loses its workability and the cernenting action is reduced. Above the rnaxirnums the rnaterial loses valuable oils to the surrounding air, and also tends to form only a thin filrn which cannot give adequate cernenting action.
R o o f i n g f e l t s c o n s i s t o f a f e l t e d r n a t o f o r g a n i c o r i n o r g a n i c fibres irnpregnaled or saturated and sornetirnes coated with biturnen. The
: }
-r n o s t c o m n f o -r 1 a -r : e t h e o -r g a n i c -r a g felts, made f-ro-rn wood fib-re t o r v h i c h i s a d d e d s c r a p p a p e r a n d a srnall percentage of rag. a s b e s t o s f i b r : e f e l t s h a v e a l s o b e e n i n u s e f o r r n a n y y e a r s , and r e c e n t l y g l a s s { i b r e r n a t s h a v e b e e n u s e d . p u l p , I n o r g a n i c r n o r e R o o f i n g f e l t s a r e d e s c r i b e d a s a s p h a l t o r t a r r e d f e l t s , depending o n t h e s a t u r a t i n g a g e n t used in their rnanufacture. Asphalt saturated
f e l t s a r e u s e d w i t h asphalt, and tarred felts with coal-tar pitch to build u p w a t e r p r o o f i n g r n e r n b r a n e s.
C o n s i d e r i n g t h e r n o r e c o r r r r n c n rag felts, the standard rnaterial i s a N o . l 5 f e l t , q u i t e f r e q u e n t r y r e f e r r e d t o
" s r 5 p o u n d o r l 5 p o u n d -t y p e f e l -t . A l 5 - 1 b f e l -t i s u s u a l l y a s s u r n e d -t o weigh l5Ib per 100 sq f-t c o n s i s t i n g o t 6 l b p e r 1 0 0 s q f t o f f e l t s a t u r a t e d with 9 lb per 100 sq ft o f s a t u r a n t . C a n a d i a n S t a n d a r d s A s s o c i a t i o n specification sets a rninirnurn w e i g h t o f . I ? . 2 I b p e r s q u a r e , t h a t i s p e r 1 0 0 sq ft for No. l5 or l5 pound_ type saturated felt and the rninirnurn felt and saturant weight are also lower t h a n t h e 6 a n d 9 ( a c t u a i l y 5 . i a n d Z . l ) .
s a t u r a t e d r o o f i n g f e l t s a r e sold in rolrs, usually 36-in. wide, with guide lines rnarked on the surface to aid the applicator in obtaining t h e p r o p e r a r n o u n t of lapping. Sorne roofing felts are perforated with u n i f o r r n l y s p a c e d s r n a l l p i n holes, which are considered to allow trapped air to escape during laying, and biturnen to enter to forrn a weII_
bonded rnernbrane.
S a t u r a t e d f e l t s a r e n o t w a t e r p r o o f and will absorb rncisture; i n a b u i l t - u p r o o f i n g the waterproofing properties of the rnernbrane depend on the existence of continuous fikns of biturnen beLween the layers or plies of felt' It is the function of the felts to stabilize and prevent ruprure or flow of the biturninous filrns and generally to strengthen the roof covering.
A c o a t e d f e l t i s p r o d u c e d by the asphalt roofing rnanufacturers by coating the saturated. felt on one or both sides with a hard asphalt; a r n i n e r a l - s u r f a c e d f e l t i s p r o d u c e d by ernbedding rnineral granules on a c o a t e d s i d e , o r i n the case of selvage roofing by ernbedding granures on p a r t o f the width of the sheet. The selvage or selvage eage is ttrat part o f t h e s h e e t w i t h o u t rnineral surfacing. I i i s s o r n e t i m e s r n e r e l y s a t u r a t e d b u t r n a y b e c o a t e d on one or both sides. Various tyPes of asphalt roofing
s h i n g l e s a r e c u t or starnped frorn rninerar surfaced prepared roofing. C o a t e d f e l t s a r e u s e d a s b a s e s h e e t s o n c e r t a i n types of roof cleck as f l a s h i n g s , a n d i n cold application roofrngs.
b -a s p -a r t o f -a b u i l t - u p r o o { i n g o n r n u l t i - u n i t r o o f d e c k s t o p r e v e n t d r i p p i n g o f b i t t r m e n t h r o u g h t h e j o i n t s t o t h e i n t e r i o r f r o r n t h e t o p l a y e r s o f t h e rnernbr ane. B i t u r n e n a n d f e l t b u i l t - u p r o o f i n g s a r e u s u a l l y g i v e n a p r o t e c t i v e s u r f a c e c o a t i n g . T h e t o p c o a t i n g o f b i t u - r n e n , c a l l . e d t h e t o p c o a t , t o p p o u r o r t o p r n o p p i n g , i s h e a v i e r t h a n t h a L u s e d b e t w e e n t h e p l i e s a n d p r o t e c t i v e d r e s s i n g i s e r n b e d d e d i n i t , T h e r n c s t c o r n r n o n l y u s e d s u r f a c i n g r n a t e r i a l s a r e g r a v e l a n d s l a g o f s i z e s f r o r n t f + t o S / B i n . O t h e r s u r f a c i n g r n a t e r i a l s s o r n e t i r n e s u s e d a r e r n a r b l e c h i p s , c r u s h e d b r i c k c h i p s , c r u s h e d v o l c a n i c r o c k , c r u s h e d l i r n e s t o n e , a n d c r u s h e d a s b e s t o s r o c k . T h e r n a t e r i a l r n u s t b e c l e a n , h a r d , f r e e o f d u s t a n d l i g h t i n c o l o u r t o b e s a t i s f a c t o r y . T h e s u r f a c i n g r n a t e r i a l a c t s a s a p r o t e c t i v e d r e s s i n g t o l i r n i t t h e d e s t r u c t i v e a c t i o n o f t h e s u n r s r a y s ( p a r t i c u l a r l y t h e u l t r a -violet) on the biturnen, to keep the felts and underlying structure cooler i n s u n n y w e a t h e r b y r e f l e c t i o n o f s u n r a y h e a t , a n d t o p r o v i d e w e i g h t t o p r e v e n t t h e f e l t s f r o r n l i f t i n g i n h i g h w i n d s . T h e g r a v e l a l s o t e n d s t o
stop the flow of biturnen by Rroviding a large nrrrnber of obstacles across any slope that rnay exist. Specified sizing is essential for corn,plete c o v e r a g e . I f g r a v e l i s t o o l a r g e , g a p s w i l l r e s u l t b e t w e e n g r a v e l u n i t s , and if too srnall rnay be easily dislodged and blown off.
D o u b l e p o u r o r d o u b l e g r a v e l l e d r o o f s a r e d e s i r a b l e o n l o w e r p i t c h e d r o o f s , w h e r e t h e s e a r e d e s i g n e d f o r p o n d i n g o r w h e r e w a t e r i s Iikely to pond even though it was not designed for it. Approxirnately 200 pounds of gravel is ernbedded in a top pour of about 50 pounds of b i t u r n e n p e r s q u a r e ; l a t e r t h e o p e r a t i o n i s r e p e a t e d w i t h 3 0 0 p o u n d s o f g r a v e l i n 7 5 p o u n d s p e r s q u a r e o f b i t u r n e n o n a s e c o n d p o u r . T h i s g i v e s a d d e d p r o t e c t i o n a g a i n s t s t a n d i n g w a t e r a n d r n e l t i n g s n o w a n d i c e . I t i s a l s o p o s s i b l e t o p l a c e t h e s e c o n d p o u r a f t e r a l l o t h e r t r a d e s h a v e f i n i s h e d t h e i r w o r k o v e r t h e r o o f , a t w h i c h t i m e a c h e c k c a n b e r n a d e f o r p o s s i b l e d a r n a g e d u r i n g c o n s t r u c t i o n .
It is very irnportant that roofing has sufficient slope to avoid standing pools of water. The cornbined attack of water or ice and sunshine on the rnernbrane is a rnuch greater ihazard. than either elernent alone, and i t i s b e l i e v e d t h a t d e t e r i o r a t i o n i s a c c e l e r a t e d a c c o r d i n g l y . T h e w e t a n d d r y c y c l i n g a c t i o n i s p a r t i c u l a r l y h a r d o n t h e r n e r n b r a n e . D e s p i t e t h e l a r g e n u r n b e r o f d e a d f l a t r o o f s b e i n g b u i l t , r n o s t e x p e r t s a g r e e t h a t i t i s e n t i r e l y u n d e s i r a b l e t o h a v e s l o p e s o f l e s s t h a n t / + i n . p e r f t , a n d e v e n w i t h t h i s a r n o u n t o f s l o p e c o n s i d e r a b l e c a r e i s n e c e s s a r y i n t h e c o n s t r u c t i o n o f t h e d e c k a n d r n e r n b r a n e t o a v o i d p o n d i n g o f w a t e r . C o a l - t a r p i t c h o r a s p h a l t i s c o n s i d e r e d s a t i s f a c t o r y f o r s l o p e s
- t
-f r o r n l / 4 t o I i n . p e r -ft, with coar-tar pitch being considered by rnost e x p e r t s t o h a v e s o r n e slight advantage. On roof decks with slopes
o v e r I i n . a n d u p to 3 in. per ft, the steep or higher melt point asphalts a r e u s e d ' I t i s n o t c o n s i d e r e d good practice to use asphalt gravel surfaced r o o f s o n s l o p e s in excess of 3 in" per ft because the surfacing has a
tendency to slide or be blown off the roof.
Smooth surface roofing, which is a tyRe of roll roofing coated o n b o t h s i d e s i n either a srnooth or veined finish with talc, rnica, or o t h e r f i n e m i n e r a l p a r t i c l e s , o r r n i n e r a l s u r f a c e d a s p h a l t roof coverings, i s c o n s i d e r e d t o be a better choice for slopes greater than 3 in. per ft. E_qoF PENETRATTON
Careful consideration in design and application rnust be given t o i n t e r r u p t i o n s i n the roof surface at pirapets, penthouses, vent pipes, chirnneys and drains" On a flat roof the principle in rnaking a built-up roof is to lay down a continuous mernbrane conforrning to tlie roof deck surface and sealing all angles forrned by the roof deck with projecting surfaces' The rnernbrane is turned up io forrn a skirting or base flashing o n t h e v e r t i c a l surfaces so that it forrns a large watertight tray. The only outlets frorn this tray are the roof drains and scuppers to dispose of w a t e r ' W h e r e i t i s n e c e s s a r y to bend the felts up to rnake base flashings there is danger of weakening or actually breaking the felts if sharp right angle bends are rnade. It is difficult to achieve a right angle bend, and w h e n o n e i s a t t e r n p t e d a void usually results at the bend where air is
trapped, so that the felts are left unsupported and subject to later darnage. F o r t h e s e r e a s o n s it is necessary to provide support in the forrn of a c a n t s t r i p o f w o o d , insulation or mortar (Figs. 4 and Z).
a rninirnurn of B in. and a rnaxirnurn t up of biturninous felts cernented to r a l t o r p l a s t i c a s p h a l t cernent. It is a s e f l a s h i n g w i t h a rnetal counter : f l a s h i n g , w h i c h i s fastened to or l e t i n t o a h o r i z o n t a l slot on the vertical surface, projects d.own over the. b a s e f l a s h i n g . s i n c e t h e r e i s d a n g e r of rupture from rrr,cvements between v e r t i c a l a n d h o r i z o n t a r surfaces, it can be argued that base frashings s h o u l d n o t b e f a s t e n e d directly to vertical surfaces such as parapet walls. I f a n B - i n . w i d e board is placed behind the cant strip, contacting the v e r t i c a l " s u r f a c e but not fastened to it, the frashing can be nailed and c e m e n t e d t o t h e board. The top edge of the board and the base flashing c a n t h e n b e c o v e r e d by the counter frashing attached to the wa[ (Fig. 5).
8 -T i , h r : o r r g h w a l l { l a s h i n g s i n r n a s o n r y w a l l s e x t e n d i n g a b o v e t h e r o o f r r r u s t b e p r : o v i d e d a n d c a r e f u l l y d e t a i l e d t o a c t i n c o n j u n c t i o n w i t h c o u n t e r f l a s h i n g s ( F i g . 6 ) . T h i s i s a d e t a i l { r e q u e n t l y n e g l e c t e d b y d e s i g n e r s , b u t w h e n s u c h f l a s h i n g s a r e n o l p r o v i d e d r a i n p e n e t r a t i o n i n t o t h e w a l l r n a y e a s i l y p e n e t r a t e u n d e r n e a t h t h e c o u n t e r - f l a s h i n g a n d u n d e r t h e r o o f i n g r n e r n b r a n e . D r a i n s e x t e n d i n g t h r o u g h t h e r o o f s h o u l d b e p r o v i d e d w i t h e x p a n s i o n j o i n t s a t t h e r o o f l e v e I , s i n c e t h e y a r e e x p o s e d t o b o t h i n s i d e and outside ternperature and wiII expand and contract.
T h e r e i s a g r e a t d e a l o f u n n e c e s s a r y a n d i r n p r o p e r p l a c i n g o f r n e c h a n i c a l e q u i p r n e n t o n r o o f s , a n d t h i s i s c o n s i d e r e d t o b e a v e r y great rnistake by a large nurnber of architects and building owners.
For every triece of such equiprnent pl aced on the roof, a nurnber of potential w e a k s p o t s a r e c r e a t e d w h i c h r n a y l e a d t o r o o f I e a k s . I f b u i l d i n g s p a c e is so valuable that such equiprnent must be placed on the roof, it is extrernely irnportant that proper structural platforrns are detailed for the equiprnent to stand on. These platforrns should be supported on round pipe colurnns, since it is rnuch easier to flash around a round colurnn than around an H-colurnn. The platforrn should also be high enough above t h e r o o f f o r r o o f i n g t o b e p r o p e r l y i n s t a l l e d . W h e r e t h e r e i s n o a l t e r n a t i v e t o c a r r y i n g s t r u c t u r a l r n , : r n b e r s t h r o u g h a r o o f o r w h e r e i t i s n e c e s s a r y t o p r o v i d e s t r u c t u r a l a n c h o r s f o r s o r n e e q u i p r n e n t r n o u n t e d o n t h e r o o f , a p i t c h p a n o r p i t c h p o c k e t h a s b e e n f o u n d t h e r n o s t s a t i s f a c t o r y r r l e a n s o f w a t e r p r o o f i n g a r o u n d s u c h p e n e t r a t i o n s ( F i g . B ) . W h e r e s k y l i g h t s o r s t a t i o n a r y v e n t i l a t o r s h a v e t o b e p l a c e d o n a r o o f , i t i s n e c e s s a r y t o p r o v i d e p r o p e r l y c o n s t r u c t e d c u r b s a b o v e t h e r o o f l e v e l . T h e n e e d f o r r o o f e x p a n s i o n j o i n t s d e p e n d s o n t h e s i z e a n d d e s i g n o { a b u i l d i n g . U n f o r t u n a t e l y , a r c h i t e c t s a n d s t r u c t u r a l e n g i n e e r s d o n o t a p p e a r t o b e a b l e t o a g r e e a n l o n g t h e m s e l v e s a b o u t t h i s i r n p o r t a n t c o n s i d e r a t i o n i n b u i l d i n g d e s i g n . I t i s g e n e r a l l y a c c e p t e d , h o w e v e r , t h a t o n a n y r a t h e r l o n g b u i l d i n g a n e ) < p a n s i o n j o i n t s h o u l d b e p r o v i d e d at each junction of the rnain portion of the building with a wing, and on the r n a i n p o r t i o n i f a n y d i r n e n s i o n e x c e e d s I 5 0 f t . C o n s i d e r i n g t h e r o o f i n g i t i s d e s i r a b l e t o p r o v i d e a n e x p a n s i o n j o i n t a t e a c h c h a n g e o f j o i s t d i r e c t i o n o r e a c h c h a n g e i n r o o f d i r e c t i o n . T h e e x p a n s i o n j o i n t i s a d e v i c e u s e d t o t a k e u p t h e r n o t i o n o f e x p a n s i o n a n d c o n t r a c t i o n t h a t r e s u l t s f r o r n c h a n g e i n t e r n p e r a t u r e o f t h e b u i l d i n g s t r u c t u r e . T o b e e f f e c t i v e t h e b u i l d i n g h a s t o b e d e l i b e r a t e l y s e p a r a t e d i n t o s e c t i o n s , w i t h a d e v i c e p r o v i d e d t o c o v e r t h e s e p a r a t i o n , a l l o w r r r o v e r n e n t a n d k e e p o u t t h e w e a t h e r . T h e u s u a l
9
-p r o c e d u r e i s t o b u i l d c u r b s a b o v e t h e r o o f a l o n g the line of the ex-pansion s e p a r a t i o n , a n d t o c a r r y t h e r n e r n b r a n e u p t h e v e r t i c a l s u r f a c e o f these c u r b s ' T h e d o u b l e c u r b i s t h e n c o v e r e d w i t h a n e x p a n s i o n c a p , u s u a l l y o f r n e t a l ( F i g . 9 ) . INSULATION T o a c h i e v e b e t t e r t h e r r n a l r e s i s t a n c e t o h e a t l o s s t h e r n a j o r i t y o f r o o f d e c k s c o n s t r u c t e d t o d a y h a v e i n s u l a t i o n . A v a r i e t y o f i n s u l a t i o n r n a t e r i a l s a r e a v a i l a b l e i n c l u d i n g w o o d f i b r e , g l a s s f i b r e , cork, polystyrene r n a d e u p i n b o a r d s o r s l a b s , a s w e l l a s c e r t a i n p o u r e d l i g h t w e i g h t rnaterials. C e r t a i n r o o f d e c k s l a b s a r e o f t h e s e l f - i n s u l a t i n g t y p e . D e s i g n d e c i s i o n s r n u s t t a k e i n t o a c c o u n t t h e s t r e n g t h , s t a b i l i t y , r n o i s t u r e characteristics a n d c o r n p a t a b i l i t y w i t h a d h e s i v e s o r n a i l a b i l i t y for fastening. M o i s t u r e , whether in the insulation initially or resulting from water vapour
c o n d e n s a t i o n a t a l a t e r d a t e , c a n h a v e a v e r y s e r i o u s e f f e c t o n the roofing s y s t e r n . T h e i n c l u s i o n o f a v a p o u r b a r r i e r o r v a p o u r s e a l t o p r e v e n t penetration of water vapour into the insulation frorn the inside is required f o r r n o s t b u i l d i n g t y p e s , a n d i s p a r t i c u l a r l y n e c e s s a r y f o r b u i l d i n g s
c a r r y i n g h i g h r e l a t i v e h u r n i d i t i e s . T h e v a p o u r b a r r i e r w i l l u s u a l l y c o n s i s t o f o n e o r t w o l a y e r s o f s a t u r a t e d f e l t r n o p p e d s o l i d each side and between p l i e s . A w e l l a p p l i e d t w o - p l y s a t u r a t e d f e l t a n d b i t u r n e n v a p o u r b a r r i e r w i l l u s u a l l y h a v e a p e r r n e a b i l i t y r a t i n g o f p r a c t i c a t l y z e r o . P l a s t i c s h e e t v a p o u r b a r r i e r s a r e u s e d i n s o r n e t y p e s o f d e c k a p p l i c a t i o n w i t h t h e
I a p s c e r n e n t e d b y a p l a s t i c a d h e s i v e . W h e n a v a p o u r s e a l i s u s e d v e r y careful application is required to avoid trapping rnoisture in the systern. T h e e d g e s o f t h e i n s u l a t i o n a t t h e e a v e s o r p a r a p e t s a r e p r o t e c t e d b y bringing the rnernbrane around the edge and sorne distance over the t o p t o f o r r n a c u t - o f f . W h i l e t h e r e i s s o r n e c o n t r o v e r s y o v e r t h i s i t e r n a s w e l I , c u t - o f f s a r e u s u a l l y p l a c e d a c r o s s the roof to separate the i n s u l a t i o n i n t o r n u l t i p l e a r e a s . I f a r o o f l e a k o c c u r s , d a r n a g e i s i s o l a t e d t o t h e c u t - o f f s e c t i o n s u r r o u n d i n g o r a d j a c e n t t o t h e l e a k . DEFECTS OR FAILURES T h e f i n a l t o p i c t o b e d i s c u s s e d b r i e f l y i s r o o f i n g d e f e c t s a n d f a i l u r e s , o r i n g e n e r a l t e r r n s t h e d u r a b i l i t y o f r o o f c o v e r i n g s . B i t u r n e n a n d f e l t b u i l t - u p r o o f i n g , w h e n p r o p e r l y a p p l i e d , can be expected to l a s t f o r r r r a n y y e a r s , a n d t h i s l i f e c a n b e i n c r e a s e d considerably by adequate r n a i n t e n a n c e . W h e n f a i l u r e o c c u r s i n t h e e a r l y y e a r s o f s e r v i c e , i t i s g e n e r a l l y t h e r e s u l t o f i n c o r r e c t u s e o f r n a t e r i a l o r n e g l e c t o f t h e n e c e s s a r y p r e c a u t i o n s . W h e n i n a d e q u a t e p r o v i s i o n i s r n a d e a g a i n s t t h e
1 0 -r o o f s u b s t -r u c t u -r e -r n o v e -r n e n t s t h a t o c c u -r a s a -r e s u l t o f d -r y i n g s h -r i n k a g e o r t h e r r n a l c h a n g e s , t h e r n e r n b r a n e r n a y b e s t r e s s e d b e y o n d i t s c a p a c i t y a n d c r a c k o r t e a r . W a t e r t r a p p e d u n d e r o r b e t w e e n f e l t s d u r i n g c o n s t r u c t i o n , o r e x c e s s i v e a r n o u n t s o f c o n d e n s a t i o n o n t h e u n d e r s i d e c a n c a u s e d e f e c t s t h a t r a p i d l y d e t e r i o r a t e t h e r o o f i n g l o n g b e f o r e i t s u f f e r s a n y d e t e r i o r a t i o n a s a r e s u l t o f d i r e c t w e a t h e r i n g . I t i s r e a s o n a b l e t o a s s u m e t h a t m a n y o f t h e r r r o r e r e c e n t r o o f i n g f a i l u r e s a r e r e l a t e d t o o t h e r c h a n g e s t h a t h a v e r e c e n t l y t a k e n p l a c e i n t h e b u i l d i n g o f r o o f s . T h e r e h a s b e e n a n i n c r e a s i n g u s e o f d e a d -l e v e -l r o o f d e c k s , a n d c o n s e q u e n t -l y p o o r -l y d r a i n e d r o o f s u r f a c e s . P r e c a s t c o n c r e t e a n d o t h e r t y p e r o o f d e c k s l a b s n o w h a v e a v e r y w i d e a c c e p t a n c e , a n d m a n y o f t h e s e a r e s u b j e c t t o c r e e p d e f l e c t i o n s , o f t e n i n e x c e s s o f l o a d d e f l e c t i o n s . T h i s l e a d s t o p e r r n a n e n t d e f l e c t i o n a n d r e s u l t s i n p o n d i n g o n t h e r o o f . T h e r e i s t h e u s e o f g r e a t e r t h i c k n e s s e s o f l i g h t e r i n s u l a t i o n s t o a c h i e v e b e t t e r t h e r r n a l r e s i s t a n c e , g i v i n g a s o f t u n d e r b e d d i n g f o r t h e r o o f m e m b r a n e a n d s u b j e c t i n g i t t o g r e a t e r v a r i a t i o n s i n t e r n p e r a t u r e . T h e i n c r e a s i n g u s e o f v a p o u r b a r r i e r s , w h i l e r e s t r i c t i n g t h e e n t r y o f r n o i s t u r e i n t o t h e c o n s t r u c t i o n , i n t r o d u c e s p r o b l e r n s f r o r n t r a p p e d c o n s t r u c t i o n r n o i s t u r e . T h e p r a c t i c e o f b o n d i n g r o o f s h a s b e e n r e s p o n s i b l e t o a I a r g e extent for a lack of adequate supervision of roofing workrnanship and
l a c k o f c o n c e r n b y a r c h i t e c t s . A d d e d t o t h e a b o v e f a c t o r s i s t h e i n c r e a s i n g a m o u n t o f w i n t e r c o n s t r u c t i o n l e a d i n g t o t h e a p p l i c a t i o n o f r o o f i n g u n d e r c o n d i t i o n s w h e r e i t r n a y b e d i f f i c u l t t o r n e e t t h e r e q u i r e m e n t s n e c e s s a r y t o o b t a i n g o o d r o o f i n g . I n a n y s e a s o n , t h e r o o f i n g c o n t r a c t o r i s s e l d o r n in a position where he can wait for entirely favourable weather conditions. O n c e t h e b u i l d i n g s h e l l i s e r e c t e d , i t r n u s t b e p r o t e c t e d f r o r n t h e w e a t h e r , a n d t h e r o o f i n g c o n t r a c t o r i s f a c e d w i t h a d e r n a n d f o r i m r n e d i a t e i n s t a l -l a t i o n o f t h e r o o f c o v e r i n g , o f t e n w i t h o u t r e g a r d f o r w e a t h e r o r t h e c o n d i t i o n o f t h e r o o f d e c k - A l t t h e s e f a c t o r s s e e r r l t o i n d i c a t e a n e e d f o r r o o f i n g u n d e r p r o t e c t i v e c o v e r s u c h a s i s u s e d f o r o t h e r p h a s e s o f b u i l d i n g c o n s t r u c t i o n . B o t h a s p h a l t a n d c o a l - t a r p i t c h a r e s u b j e c t t o a s l o w p r o c e s s o f o x i d a t i o n o n t h e r o o f . T h i s i s a c c e l e r a t e d b y h e a t a n d l i g h t f r o r n t h e s u n , a n d r n a n y o f t h e o x i d a t i o n p r o d u c t s a r e s o l u b l e i n w a t e r . O t h e r s a r e g a s e o u s a n d v o l a t i l e . T h e l o n g t e r r n e f f e c t o f e x p o s u r e t o t h e s u n a n d e l e r n e n t s i s a g r a d u a l l o s s o f b i t u r n e n f r o r n t h e s u r f a c e a n d e v e n t u a l l y c r a z i n g a n d p i t t i n g . W h e n r n o i s t u r e p e n e t r a t e s t o t h e f i b r e s o f t h e f e l t s , d e t e r i o r a t i o n r n a y r a p i d l y i n c r e a s e . T h e r e i s a l s o a l o s s o f f l e x i b i l i t y o n e x p o s u r e a n d t h e r n e r n b r a n e r n a y b e c o r n e b r i t t l e . T r a f f i c o v e r o l d f e l t s t h a t a r e w r i n l < l e d o r b l i s t e r e d c a n c a u s e c r a c k s w h e r e w a t e r r n a y p e n e t r a t e . F o r t h i s r e a s o n , i t i s n e c e s s a r y t o h a v e a r e g u l a r i n s p e c t i o n
- l l a r r d m a i n t e n a n c e p r o g r a m w i t h r e p a i r s a n d r e s u r f a c i n g c a r r i e d o u t a s n e c e s s a r y . I n t h i s w a y t h e u s e f u l s e r v i c e o f t h e r o o f i n g c a n b e g r e a t l y i n c r e a s e d . N o r m a l d e t e r i o r a t i o n a s a d i r e c t r e s u l t o f e x p o s u r e t o w e a t h e r i s g r e a t l y a c c e l e r a t e d b y o t h e r f a c t o r s r e s u l t i n g f r o r n i n c o r r e c t d e s i g n c o n s i d e r a t i o n s a n d p o o r w o r k r n a n s h i p i n a p p l i c a t i o n . C r a c k s a n d t e a r s f r o r n s u b s t r u c t u r e r n o v e m e n t s , b l i s t e r i n g a n d r i d g i n g f r o m e n t r a p p e d c o n s t r u c t i o n r n o i s t u r e o r e x c e s s i v e c o n d e n s a t i o n , a n d p i m p l i n g a n d b l i s t e r i n g a n d l o s s o f g r a v e l f r o r n p o n d i n g o f w a t e r a l l c o n t r i b u t e t o m o r e r a p i d d e t e r i o r a t i o n . T h e r n o r e c o m r r r o n d e f e c t s a n d t h e i r c a u s e s r n a v b e l i s t e d a s f o l l o w s :
Tearing and splitting: I. Differential rrroverrrent at cracks or joints i n t h e s u b s t r u c t u r e .
Z . P e r f o r a t i o n o f u n s u p p o r t e d f e l t .
3 . P e r f o r a t i o n o f b l i s t e r s o r r i d g e s b y t r a f f i c . 4 . S h a r p b e n d s i n f e l t .
Pimpling on top layer of
b i t u r n e n : E x p a n s i o n o f t h e m o r e v o l a t i l e p o r t i o n s o f b i t u m e n , o r o f a i r o r w a t e r , i n s u n n y w e a t h e r .
B l i s t e r s b e t w e e n l a y e r s
of felt: Ercpansion, in sunny weather of entrapped air
o r w a t e r . B l i s t e r s b e t w e e n f e l t
and deck: E>cpansion, in sunny weather, of entrapped air o r w a t e r - p a r t i c u l a r l y l i k e l y t o o c c u r o n i m p r o p e r l y c u r e d c o n c r e t e d e c k s o r c o n c r e t e f i 1 1 s . R i d g i n g : M o i s t u r e r n o v e m e n t a l o n g f e l t s o r d e c k s , f o r i n s t a n c e w h e n t h e f e l t i s n o t p r o p e r l y b o n d e d . L i f t i n g a t l a p s : l . B a d b o n d i n g i n i t i a l l y , d u e s o r n e t i r n e s t o
fishrnouthing or failure of the applicator t o s e a l e d g e s w h e n l a y i n g o r u n r o l l i n g t h e felt rnechanically or rnanually, or failure t o b r o o r n d o w n t h e f e l t s p r o p e r l y .
Z . P u l l i n g a s a r e s u l t o f t h e f o r r n a t i o n o f b l i s t e r s . A l l i g a t o r c r a c k i n g : H a r d e n i n g o f s u r f a c e l a l e r s o f a s p h a l t b y
lz
-c r a -c k s t h a t b e -c o n ) e p r n g r e s s i v e l y d e e p -c r a s t h e s m a l l i s l a n d s f o r r n , e d b y t h e c r a c l < p a t t e r n c o n t i n u e t o s h r i n k . Local or gela,eral d e t e r i o r a t i o n a n d embr ittlem,e,nt: P r e m a t u r e d e t e r i o r a t i o n f r e q u e n t l y r e s u l t i n g f r o r n i n a d e q u a t e s l o p e t o d r a i n s a n d s u b s e q u e n t p o n d i n g o f w a t e r o n t h e r o o f , s o m e t i r r r e s cornbined with improper application of the s u r f a c e d r e s s i n g-o n e -o f t h e p r -o b l e r n s f a c i n g t h e industry at present is the w r i n k l i n g o f t h e m e m b r a n e over joints in insulation. I t i s b e l i e v e d t h a t t h i s i s d u e e i t h e r t o dimensional change or warping of the insulation o r t o p r e s s u r e s d e v e l o p e d beneath or within the roofing layer as a r e s u l t o f w a t e r , w a t e r v a p o u r or air trapped in the insulation. w h e n t h e w r i n k l e p a t t e r n o c c u r s , it is often not obvious until the gravel is s c r a p e d o f f , a n d s o m e t i m e s does not seem to cause serious deterioration. I n o t h e r c a s e s t h e w r i n k l e s are so large that there is a loss of gravel a n d b i t u m e n f r o m t h e top so that serious deterioration takes place. T h e r e i s n o c o m p l e t e understanding of or solution to this problern at the p r e s e n t t i r n e , a l t h o u g h venting of the insulation has helped in some cases. CONCLUSION
T h i s g e n e r a l o u t l i n e o f roofing cornbined with the Glossary of T e r m s ( A p p e n d i x A ) is intended to provide a background for rnore
{LLTGATORTNG APPLTCATOR APPLTCATTON TEI{PERATI'RE (Bltumen) APPROVED CONTRACTOR ASPHALT ASPIIALT PRI}MR BARGMOARD BASE SHMT BITI]I"IEIV BITUI,IE}I BUBRLE BLISTER APPI,N}TX A
Gtoss^ilY oF n0OtrIi\IG TEtrr"ls
Sur"face cnackln6 due to oxtdation and shri.nhage s t n e s s e s " w h i c h s h o r , r s a s r o p e t i t L v e m o u n c l i n g o f an asphalt surface, resernbling the hlde of an a l l 1 g a t o n ,
One r+ho sells asphalt noofings, shingles and s i d l n g s o n a n a p p l l e d b a s i s .
The tenporatune of the hot bitunen r,rhen applted on the roof whlch should be not more than !09F l e s s t h a n t h e c o r n e c t k e t t l e t e m p o n a t u r e o An indtvlduale pantnership on conporatLon genenally quallfied by technical tralning and experl.enee to dLrect o:' perform pnoperLy the appllcation on nepair of nooflngo waterpnooflng or sheot meta] wo::k, as requlred ln the roofing lndus tryo
Aspha)-t ls a natural product found :ln lange d e p o s i t s c a l l e d l a k e s n a n d l s a l s o a b y - p r o d u c t o f t h e n e f i n i n g p r o c e s s e s o f p e t r o l e u m . M o s t of the asphalt used ln Canads as an lmpregnatlng and w aterprooflng agent ln asphalt r"oofing produe bs 1s tho r"esLdue of petroleurr dlstlllatlon wlth some nofinomento
A sol"ution of asphalt in potroleurn solvent, used to pnepare concrete roof <lecks for the applicatlon of hot asphaLt, The prlnier lays dust and Lmpnoves the adhesion of the molten asphalt to the rooi d.ee.k"
The decorative board cover"ing ttre pro jectlng p o r t i o n o f a 6able noof" A l s o r e f e r r e d t o a s
the verge board.
A heavy slreot of felt sourotimes used as the first p1y tn bulIt-up roofing"
A genenic ter"n describlng any native mixture of heavy hydrocanbons j"n viscous or" solid for"n, and in the noofing Lndustry may be used to indicate e i t h e r a s p h a l t o r c o a l - - t a r p i t e h ,
See BLISTER." BLIIEBERRY, Pfl'lPLfNG"
A n e n e l o s e d r a i s e d s p o t s h o w i n g o n t h e s u r f a e e o f pnepar.ed roofi-ng and built-up rooflng" Very smell blisters confined to the surface ar"e called weatl:.ez blisters. pirnpling or bluebe::r"ies as a result of natural weathenina. The r.,rone evident and more
s e r " i o u s b l i s t e r s d r e s t r u c t u r a l b l i s t e r s . T h e y oceur in rrrany forms of deforrnation and are not c o n f i n e d t o t h e e : < p o s e d s u r f a c e u T h e y a r e c a u s e d mairily by the expansion of trapped air and water v a p o u r o n m o i , s t u r e o r o t h e r g a s e s . A i r a n d moisbur:e trapped r.rithln the construction tend to expand dur"inq a ri se ln air teinperature or f roi'n t h e h e a b o f t h e s u n " a n d t h - i - s e r p a n s i o n c a l l s e s
BLISTER ( C o n t t d ) BLUEBERT{Y BOND BREATItrR BROOMING BUCI(LING BUILT-i'P ROOF]NG t h e p l i e s o f b l r e r o o f i n g t o s e p a r a t e a n c l b u l g e t h e r o o f s r r r f a c e i n a b a l l o o n e f f e c L " T h e blistens are spongy to tho toueh, and nay occur: between any of tlr.e layers of roofing felto or botwoen motnbrane and deckn or membrane and i n s u l a t l o n .
A b e n m s o m e b i - r n e s u s e d t o d o s c r i b e w e a t h e r b l i s t e r s " T h e s e a r e s m a l l s u n f a c e t r l i s t e r s , w h i c h c a n b e s e e n in large numbers over the entire roof area, more predominant during warm weather where roofs are orposed directly to the sun, and which arc a resuLt of naturaL weathering of the sunface bitumen"
Vo1atiles and w ater vapour ln the bltumen tend to be drlvon off by heat, and when the gases ar"e tnapped they form smal1 blisters" Thls Lype of bllstering usually does not cause any fallure durlng the normal life of the roof" Al-so sometimes oalled pinpllng, pin blistering and bitumen bubbling"
Adherence betrueen plies of felt, or" betiueen felts a n d o t h e r e l o m e n t s o f r o o f s y s t e n s " w h i c h u s e bitumen or othen matenials ab the cement;lnq agentn A t y p e . . o f r o o f v e n t c o n s i s t i r r g o f a h o o d e d f l a n g e d pip_e 2tr to Brr in diameter, penetrating the roofi'ng memb::ane to allor^l escape of molstune from insulation" T h e p , n e s s i n g o f t h e f e l t s i n t o c l - o s e e o n t a c t L r i t h the biturren lrunediatel-y follorving the application of bltunen and fe1b, usually accomplished with a wide sbable or dech firpe broomn The impontance of broomJ.ng to achieve proper and conrplebe ad.heslon is ofterr not nealized even uithin the lncj.ustr:y" Warping on wr"inl<Ling of the roof memtiraneo
A b i t i J - t ^ ' u p r o o f i n g c o n s i s t s o f p l i e s o r l a y e r " s o f noofing felt bonded together on slte r,litlr hot bitumen" A proLeetl-ve sur:,face eoating of gnavel o:r slag is sornetintes enrbedded in a heavy top cr:ating of hot bitumen. It i s laid clown to con-forri to the roof deek, and to protect al} angles f o n n e d b y t h e n o o f d e c k w i t h p r o j e c b i n g s u r f a e e s , an.d fonns a single*unit flexible waterpr"oofed mer,rb::ane fastened to the deck by cementing on by ccinenting and nailing" The simple principle on fl-at roofs is to tunn the mernbnane up to form a sllintin6 or base f1 ashi-ng on the verticerI sunfaces, rnaking a lange watertight tray" The only outlets f::on this tray ane the roof drai-ns to dispose of wn be.L"
i r l a t t i n d i s c w i t h c e n t r e n a i l h o l e s " u s e d t o f a s t e n s a t u r a t e d f e l t t o t h e r o o f d e c l c o
CANT STII]P
CAP S}IIJET CEI.,IENT,
ASPI ALTTC PTASTIC COAL TAR PTTCII
COATTNG ASPIIALT COLD PATCH COLD PROCESS COII,AR COI\B ROOF COI{POSTTION ROOFING CONDET{SATTON CONDUCTOR COPTNG C O R I T I C E CRAZTNG CRICI{ET
A bovol-lcd support used at the lntersection of t I'r.e
roof docli r,ri-l;h vcrti"cal- surf,aces so that bends i-n
the roofing rnernbrane to forn base fl ashinfls can be
lnade r"ritlrollt brealiing the felts. They rrrCy be a
bevollecl strip of nood or insulatlon and in some
c a s e s c c r n t n t g r o u t o r l i g l e t w e i g h t c o n c r e t e " The top p1y of a buj.l-t-alp roof forming the
finislred surfnce of, the roof"
A mixture of espiralt, solvent and mlneral
stabilizer used fo:: exanrple to adhere flashings
o r t o f i l l p a n f l a s h i n g s .
A bituminous material pr.oduced by disttlling crude
tar ::esidue derived fron the coking of coalo Tt
is used as the waterproofing matenial for tar and
gravel built-up roofingg.
A w e a t h e n n e s i s t a n t a s p h a l t u s e d a s t h e p n o t e c t i v e s u r f a c e i n p r e p a r e d r o o f i n g s "
The r.epair of e roof leal< using prepared. roofing s a t u r a t e d f e l t o r f a b n i c a n d p l a s t L c c e m o n t .
A method of applying built-rrp roofing uslng
unheated cernent" Also C0ID APPLICATI0N"
A m e t a l c a p f l a s h i n g f o r a v e n t p l p e p r o j e c t i n g a b o v e a n o o f d e c k "
A d o u b l e s l o p l n g o r g a b l e r o o f ,
A1i- types of asphalt roII rooflng and shingtes"
The change fron gas on vapoun to liqutd form"
A pipe for conveying i:ain waten from the roof
guttor to a drain, or from a roof drain to the
s t o r r n d r a i n ; a l s o c a l l e d a l e a d e n , d o w n s p o u t or down pipe"
The cap or hi-ghest covering course of a wa1I,
usually ove::hanging the walt and having a sloping
t o p t o c a r r y o f f w a t e r "
P r o j e c t i o n a t i h e t o p o f a w a l l o A t e n m a p p l i e d
to construction under the eaves where the roof
a n d s i d e w a l l s m o e t . T h e t o p c o u r s e , o r c o u r s e s , of a wal1 rrhen treated as a crouming member.
A series of hairl-ine cnacks in the surface of
w e a t h e r e d m a t e r l a l s .
A snall false r-oof" or the elevatlon of a part
of a noof surface as a means of throruins off water fron behlnd an obstacle such as a-chimney" A I s o s o m e t i n e s r e f e r r e d t o a s a s a d d l e "
ctmB
CUI BACK CUT OFF DECK DECK, DEAD LEI/M, DECK CLIPS DIPPER DOR},IER DOUBLE COVERAGE DOUBLE POUR " 4 4A r'1a11 of wood oI' nlasont:y bul-It above thc level of the roof, surrounding a roof opening such as
r e q u i r e d f o n i n s b a l l - a t l o n o f r o o f f a n s o r o t h e r " oquipment" ancl nt expansion joints in the r-oof deck, A solutlon of biturnen in er volati-l-e solvent. Cut b a c k s a r e u s e d a s p r l m e r s , c o l c l a p p l i c a t i o n
comentJ-ng a4ents, and damp pr.oofing eoatings. A piece of roofing mombnane consisting of one or m o r e l a y e r . s o f f e l t u s e d t o s e a l . t h e e d g e s o f l n s u l a t i o n a t t h e e n d o f a d a y t s w o r k o o r t o separato the insulatlon into multiple areas so that, ln caso of a roof leaho any darnage would be lsolated to the cut-off sectl-oyr surrounding or a d J a c e n t b o t h e l e a l < o
The structural roof to the top surfaee of whlch a roof eovering system ls applied. Sone forty o:r more ::oof dock types are curr-ently 1n use in the construction lndustny"
A r o o f d e c k v r l r e r e n o d e l l b e r a b e a t t e m p t h a s b e e n made in design or" construction to provlde slopes t o t h e r o o f d n a i n s " S u c h a r o o f i s s o l d o m achieved ln praetice because of norrnaL stnuctural d e f l e c t l o n s , a n d t l r . e l n a c c u r a c l - e s o f c o n s t r u c t l o n n w h i c h g i v e r i s o t o d e p r e s s L o n s l n t h e s u r f a c e " Thls term ls a loose one tlr.at may mean a metal fasten5-ng device to hol-d lrultlple unit noof dock materials to the stnnetural supportlng membens, a f a s b e n l n g d e v i c e i n s e r t e d . l n p l y w o o d d e c i r s t o
pnevent uneven defleetions bobween opposlng plywood J o i n t s , o r a n y o n e o f a v a r i e t y o f d e v l c e s t o
f a s t e n i n s u l a t i o n t o a r o o f d e c k . A 1adle for pourlng bittmren"
Thi.s usually refers to a dorrnen windoru, the framlng of l,rhlch pr"oJects from a sloping roof. T h o d o n i r e r l t s e 1 f i s t h e h o u s e - l i k e s t r u c t u n e , usually with a gabl-e roof, in which the win<low is c o n t a i n e d "
Spllt sheet nrineral surfaced asphalt nol1 roofing which.o l.ilrerr 1ald, results in a two-ply applicatlon, The application of the top coating of biturnen and the gravel su::facing of a built*,up roofing in two s e p a r a t e a p p l - i c a L i o n s , u s e d o n d e a d l e v e L r o o f s " partl-eu1ar];r lyitut't i,he noof is d esigned for floo<ling w i t h w a t e r " T h i s i s a c c o m p l i s h e d b y e r r b e d d i n g a qr{e,ntity of gravol in a firit top pour of blturnen and later r"cpeat:i-ng the operation r,rith additional gravel enbeddecl in a second por;.r of bitumen.
DOhrNsPouI DRAT}T PIPE DRIP EDGE DRIPPAGE DRY S]IEET EAVES E/|VES BOARD EAVES TROUGH ETITLSTF]ED ASP}IALT MID LAP EXPA}ISTON JOII{T
'.['he ncta] pilto usecl to clrain water from a roof, S p o c i f : L c a } I y t h e c o n n e c t i o n b e t w e c n e a v e s t n o u g h and storni drnin. AIso downpipon concluctor, l e a d e r ' , d r a l - n p i p e "
The ruetal or othen piJre used to draln water: fronr a roof" Also clownspout, dol.rnpi_pe, concluctor, l e a d e r ,
Itletal lrsed at th.e eaves of a roof forrned to carrv l'rater from the buildlng"
Bltumen natenLal that drlps thnough::oof docl< j o i n t s , o r o v e r t h e e d g e o f a r o o f d e c k .
An u:rsaturated felt or paper used for exanrple on w o o d d e c k s t o p r o v e n t a s p h a l t o r p i t c h f r o m p e n e -tratlng the jol.nts in the deck and leaklns tnto t h e b u i l d i n q b e l o w "
T h e p a r t o f a r o o f w h i c h p r o j e c t s or the lower odgo of the part of a hangs a wall"
o v e r t h e s i d e w a I I " roof that over-A s t r i p o f w e d g e - s h a p e d b o a r d . u s e d a t the eaves of
a r o o f t o b a c k u p t h e f l r s t c o u r s e o f s h i i r g l e s , t i l e s o r s l a t e s .
A gutter at the eaves of a roof fon earrylng off r a i n w a t e r " T t r n a y b e o f w o o d o r m e t a l a t [ a c h e d t o t h e e a v e s e o r a b u i l t - 5 - n p a r t o f t h e e a v e s design u s u a l l y l - l n e d w i t h m e t a l " S t r a i g h t r u n a s p h a l t l i q u e f i e d b y c l a y e m u l s i f l o r s a n d w a t e r " F i n e L y d i v i d e d c l u . s t - I i k e p a r t i c l e s o f a s p h a l t a n e ) l e p t i n s u s p e n s i o n j _ n a c o l d b u t u n s o l i d i f i c d s t a t e " C e m e n t l n g a c t i o n b y s o l i d i -f l e a t i o n b a k e s p l a c e w h e n t h e w a l , e r i n t h e e m u l s i o n e v a p o r a L e s , A s p h a l t d l _ s p e r s o d i n w a t e r "
The amount of overlap at the end of a ply on the a p p l i c a t l o n o f r o l l r o o f i n g f e l t s f o r b u j _ l t - u p ro ofi- ng "
A devi.ce used to talre u"r th.e mo'bion of expansion and contnaction due to cl-range in temperature fon building servj-ees and buildlnfl structure" On large roofs ttris provision for tlre novement of the naterj.als forrninq the walls, roof , roof cleck and
curbs above the r-oof o alon,q the line of the expansion sepanation ancl carr"y the rooflng membrane up the v e r t i c a l s u r f a c e o f b h e s e c u r b s . T h e d o u b l e c u r b 1 S t h e n c o V e p g f l r " r i th n r r A Y n q h . i - o n C a p u S U a l l - y O f m e t a l "
FASCIA I{ILT FmT, ASBESTOS FELT, ASPIIAiT SATURltTED FmT, COATED EE,T, GLASS FE[,T IIAIVDTER FEI,T LAMR FH,T, NO. 15 Ftr,T, PERITORATED Ftr,T, RAG Fff,T, TAR SATURATED FTLL - 1tr(r
The flat oubside nlember of a eorn-ice placed ln a vortlcal position. Ivlono commorl usago ls to descrj.bc any cover boand at the odge or oaves of a flat on sloplng overllanglng roofe
A v e r y g e n e r a l - t o r m u s e d t o d e s c r i b e r o l l r o o f i n g m a t e r ' l a 1 s , c o n s l s t l n g o f a m a t o f o r g a n i c o r i n -organlc flbres unsaturatedo saturated, or saturated and coated urlth asphalt on coal-tar pltch.
Felt rnade fnom asbestos fibres, lmpregnatod on lmpregnated and coated with asphalt.
Any type of felt that has been lnpregnated or satunated with asphalt. Sometlmes nefenred to as m e r e l y a s p h a l t f e l t o w h l c h c a n a l s o m e a n f o l t
lmpregnated and coated wtth asphalto
Bltumen saturatod felt that has beon coated on one on both sldes wlth bltumen by further processing" C o a t e d f e l t m a y b e u s e d a s b a s e s h e e t s , l n s o m e types of built-up rooflng, and with mlneral surfacing added as cap shoets and shlngles.
A non-woven mat o.f fLexlble glass fib:re, forrnod by spreadlng flbrous matonlal over a screen and pressing lt togethor to for.rn a sheet" For use ln bullt-up nooflng appllcatlons the glass fibre mat is lmpreg-nated wlth asphalt.
A man on the roofLng cnew who puts the folt noll or sheet lnto posltion, and whg wlth tho felt runnons is responslble fon unnolllng felts and covering the roof dech or lnsulatlon wlth the correct number of p 1 l o s
"
A plece of nechanlzed equlpment for spreadlng bltumen and 1ayin61 felt in a single openation. A s p h a l t o r c o a l - t a r s a t u n a t e d f e l t w o l g h l n g approxlmately 1! pounds per 100 square feet.
A s p h a l t s a t u r a t e d f e l t p e n f o r a t e d w i t h s m a l l h o l e s o whlch al1ow tr.apped alr to escape dur:ing la;rinU,
and bitumen to entor" to fonm a l.lell-bonded merrbrane" A type of heavy paper nado prl-nctpally frorr wood. flbne, w ood flour, waste paper and a snal1 percentage of rago It r^las forme::l;' made pninclpally of rag
when flrst used in the rranufactune of roofin,3 rrraterials" R a g f e l t i s s a t u r a t o d o r s a t u r a b e d a n d c o a t e d w i t h
blturnon to produce a variet)' of rooflng felts, and p r e p a r e d r o o f l n g "
F e I t i m p r e g n a t e d o r s a t u r " a t e d w i t h c o a l - t a r p l t e h , Llghtwelght c oncreto placecl on a level roof deeir in v a r y i n g t l r i c l r r r c s s e s t o b u i L d s l o p e s t o t h e r o o f d r a i n s . A I s o r e f e m e d t o a s s c r e e d j _ n f "
F]LLER FIITE I,{ALL FISH I:'IOUT}F I{tXTURES FLASITING FLASHIiTG, BASE FI,ASHING, CAP ELASHTNG, COUNTER FT,ASIII'IGe EAVES tr{,ASIIJI{G, STEP
Finely dlvided mineral aggregate used as an oxtenden or to lmpnove tlie properties of coatl_ng asphalt and plastlc asphalt cement"
Any wall built for the purpose of restrictine or pr_eventing _the spread of flrc ln a bullding. - Such walls of sol-id masonry or concrete sonretlmds sub-divide a bullding from the foundations to two or more fee'b above the noof"
The naLls and cement requl_red for, and usually packed wlth ro11 noofing.
Any pnotective and waterproof naterial r-rsed to protect against weather the juncture of a r.oof and
d i s p o s e o f t h e w a t e r o B i t u m i n o u s f e L t s a r e u s u a l l y used for a bitrmrl_nous rogfing.
A s t r i p o f f l a s h i n g m a t e n l a l u s u a l l y metal used to p r o t e c t t h e t o p e d g e o f b a s e flashings" B a s e flashings are canried up along vertl'cal surfaees projecting above the roof deckn and the cap flashing fastened to on let into the vertieal sunfale pro;ecEs down over ttre top edge of base flashing" AIso
c a 1 l e d c o u n t e n f l a s h i n g " See CAP FLASIIING
Treatment of the edge of a roof r^rith felt and,/or m e t a l "
Individual small pieces of metal flasLrtng mat.enial-used to flash around chimneys, dormens and such p r o j e c t L o n s a l o n g t h e s l o p e o f a roofo T h e individual pieces ane overlapped and stepped. up t h e v e r t l c a l s u r f a c e ,
I,T,ASIIf I'lG, TIIIIU I.fALL FLASII]}IG BT,OCK FT,AT NOOF }I]LL P]TCH GABI,E GABLE N,ID GABLE ROOF GAIN,REL ROOF GLAZE COAT Gn/\iTUtES CRAVEL - A t l
Flashinfl extcnding conpletoly through lt nlasonry vraII" Dosi,qned and apptied in cornbination vlith counter fLashings, to prevent waten vrhich nay enter the r.rall. fronr proceedin,3 clorvnruand in thc wall on into the roof dock or roofin,r: system" Arnong anclritects I errors and ontissions, ilr.e omission of thru-wall j'lastrings is one of thc nost corrron. A s o e c i a l l ; , ' d e s i g n c d m a m n r y b l o c l i h a v i n , l a slot or opening into nhich tho top edge of ilre rocf f1_ashinq c a n b e i n s e r t e d a n d a n c h o n e d . A l s o n a . q g l e b I o c k . A l e v e 1 o r n e a r l y l e v e l r o o f n A I s o g e n e r a l l _ ) r a p p l l c d t o r o o f s l r a v i n g l o v r s l o p e s o r - i n c l : i n e ! t o t h e r o o f d r a i n s "
A double sloping roof w:lth the rj-se equal to hire width of the span of roofo Appr"oxinatelf, 631,.0 a n g l e o f p i t c h r d t h h o r i z o n t a l .
The end of n buildinsl as disti_nguished. fron ilrt,. front or rear side. The trlangular end of an exterior waLl fnom the level. of the eavcs to ilre nidge of a cloubl-e
s L o p e d r o o f o
An end waI1 of a building with a gable formed by t h e r o o f "
A r i d g e d o r d o u b l e s l o p e d r o o f w h i c h terminates at one end or both ends in a gable"
A type of roof r,rhich has its slope broken by an o b t u s e a n 4 1 c , s o t h a t t h e l o v r e r . s l o p e i s s t e e p c r than tlte upllcr sIope, A cloub.Le sloped roof h.avilg t l v o p l t c h e s o
A mopplnl of bitullen on exposcd felts to protect
then fnora the weather pending conpletion of the ..iob. TIr.e niner"al particles cf a gradcd size wlr-ich are er;rbodded in thc coating asphalt cf shingles ancl nooflng.
sunfacing mater"ial" GRAVE, STOP
GRAVET,LTNG-IN GROIII or GROI]TING GI'TTER HANGTNG GIITTM HEADER TtrGH I..Ttr,T POIM HIP }trP ROOF
II0rsT
}IONIZENTAL APFLTCAT]ON HOT STUFF TCE DAH - 4 9The operatlon of ernbeddin4 a gravol sunfacing to a top mopping or a top pour of bl-turnen on bui-lt-up :roofing.
A fluid cemont montar mixture used to fill joints and c a v i t i e s o f m a s o n r y . 0 n r o o f d e c k s , t h e ;oints
botween many tlpee of precast roof declr slibs are grouted wlth cenent grout.
Metal or wood tnough at the eaves of a roof to carry r:ain water fr:orn the roof to the downspout.
An eaves guttor held ln place by wlre or strapp5_ng" The beam lnto which the coruxon Joists are fttted when framlng ar"ound a noof opening, The headers arro p3-aced so as to fit between two 1_ong beams or trimmers to suppont the jotst ends.
Ugga]Ly ln refenenco to asphalt usod. on sloping roofso whlch lras a nelatively trigher nelting tempenature than othen bltumcn used, on lorven slope noofs. See also softenlng point"
The apex of the outer angLe formod by the meetl_n6 of two sloplng sldes of a roof, whose eaves or wall -plates meet at a nlght angle, A hlp raften extends f:rom thb cornen or intersoction of the platesto the n i d g e "
A roof which rises by lnclined planes fnom alI foun sldes of a bulldlng. The line wher:e two adjacent sloplng sides of a r.oof rneet is ca1led the Lrip" A l s o c a l l e d a c o t t a g e r o o f .
A device used fon holsting rooflng materials from gnound to roofn
The apptr-ication of roll noof:ilng parallel to the eaves,
Heated bitumen used for .the ;@pllcation of a built-up noofing membrane.
sunface of the icc dam can cause r.rater to basir up and penetrate .the .Iaps of rnultipl_e unit roof
coverin.;:s.
Is the angle made by a noof with a horizontal .plane. T h e i n c l i n e i s u s u a l l ; r e x p r e s s e d a s r r L n c h e s o f r i s e p e r f o o t o f r . u n r r . S e e a l s o S l o p e , p i t c h "
