Exposure of new roofing systems

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Exposure of new roofing systems

NATIONAL R E S E A R C H COUNCIL CANADA

DIVISION O F BUILDING R E S E A R C H

E X P O S U R E O F NEW ROOFING SYSTEMS

by

P.

M. Jones I n t e r n a l R e p o r t No. 325 of the D i v i s i o n of Building R e s e a r c h OTTAWA F E B R U A R Y 1 9 6 6

P R E F A C E

The Division for s o m e y e a r s h a s directed p a r t i c u l a r attention t o roofing p r o b l e m s , which appear t o b e i n c r e a s i n g in frequency of o c c u r r e n c e . While many studies have been directed t o the p r o b l e m s of the commonly used roofing m a t e r i a l s , i t h a s been n e c e s s a r y a l s o t o keep in touch with new developments. T h e p r o j e c t now described, involving the exposure and observation of ten new roofing s y s t e m s , s o m e of which a r e s t i l l i n t h e e x p e r i

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m e n t a l stage, was intended t o provide a n opportunity t o become f a m i l i a r with the new m a t e r i a l s involved. The r e s u l t s of the exposure observations will a l s o b e useful but should not be r e - garded a s conclusive evidence of the r e l a t i v e m e r i t s of the s y s t e m s and m a t e r i a l s .

The author, a c h e m i s t and a r e s e a r c h officer in the Organic M a t e r i a l s Section h a s responsibility for l a b o r a t o r y studies of bituminous m a t e r i a l s , which in r e c e n t y e a r s h a v e been d i r e c t e d mainly to roofing m a t e r i a l s .

Ottawa

F e b r u a r y

1 9 6 6

N. B. Hutcheon, A s s i s t a n t D i r e c t o r

EXPOSURE O F

N E W

ROOFING

SYSTEMS

by

P.

M. J o n e s

One of the p r i m a r y considerations in the e n c l o s u r e of a n environment i s the provision of a roof that will prevent the e n t r a n c e of w a t e r . F o r c e n t u r i e s t h e p r i n c i p l e of shedding of water by shingle-type roofing h a s been used successfully, but t h e development of flat o r n e a r flat r o o f s and m o r e recently, the unusual contours such a s curved shells, domes, hyperbolic paraboloids and folded p l a t e s have placed m o r e exacting

r e q u i r e m e n t s upon the waterproofing. The u s e of a waterproofing m e m b r a n e i s now common. T h i s m e m b r a n e depends upon i t s inherent waterproofing qualities t o function effectively r a t h e r than upon the shedding principle which i s used in shingle -type roofing.

T h e m o s t common of t h e s e waterproofing m e m b r a n e s i s the bituminous roofing and although the m a t e r i a l h a s been known for many c e n t u r i e s it h a s only been used a s a roofing m a t e r i a l for the l a s t hundred y e a r s . In r e c e n t y e a r s c h e m i c a l technology h a s produced m a t e r i a l s that a r e considered suitable a s roofing

m a t e r i a l s , p a r t i c u l a r l y for t h e m o r e exotic roof shapes that a r e difficult t o roof with conventional bituminous m a t e r i a l s . Many of the new s y s t e m s s t i l l u s e bitumens in the roofing either a s adhesives o r a s the waterproofing element. Many s y s t e m s , however, a r e v e r y different f r o m bitumens in composition,

application technique and i n final appearance. The old m u l t i p l e - ply built-up s y s t e m i s , i n t h e s e c a s e s , replaced with single f i l m s that a r e thin but high in strength, have high r e f l e c t i v i t y and a r e r e s i s t a n t t o traffic. In the l a s t few y e a r s s e v e r a l such s y s t e m s have been proposed. In o r d e r t o provide some oppor

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tunity t o examine the p e r f o r m a n c e of t h e s e m a t e r i a l s under

Canadian conditions and to become m o r e f a m i l i a r with them, a n exposure p r o g r a m h a s been s t a r t e d .

T h i s r e p o r t i s a description of the n a t u r e of the m a t e r i a l s exposed, t h e i r application and s o m e r e s u l t s of a visual

ROOFING MATERIALS EXPOSED

Ten types of roof s y s t e m s have been exposed and t h e s e a r e listed in Table I. The m a t e r i a l s w e r e obtained d i r e c t l y f r o m the manufacturer of the m a t e r i a l and w e r e either purchased or given by t h e manufacturer a s s a m p l e s f o r the exposure p r o g r a m . The m a j o r i t y w e r e being m a r k e t e d , but s o m e had not p r o g r e s s e d beyond the experimental stage.

ROOF DECKS

The decks w e r e constructed f r o m 5/16 -in. plywood on a 4 - x 12 -ft f r a m e made f r o m 2 - x 2 _{-in. lumber on 16 -in.} c e n t r e s . Each panel h a s a 2 in. high cant s t r i p along one of the 12 -ft sides so that each roof would shed i t s own water. Each panel h a s a slight slope towards the cant s t r i p , and the roof panel i s a l s o sloped f r o m the r e a r of the roof towards the front to e n s u r e that the panel sheds water. The completed decks w e r e laid shingle fashion a s shown in F i g u r e 1.

The completed decks and roof s y s t e m s w e r e installed over the components of a "Bailey-Bridge" s t r u c t u r e and s e c u r e d t o it.

APPLICATION O F THE ROOF SYSTEMS

Nine of the roof s y s t e m s w e r e applied t o the decks in the l a b o r a t o r y and when completed w e r e t r a n s p o r t e d to the exposure

s i t e and installed t h e r e . The tenth r o o f , the hot asphalt built-up roof, was applied to t h e installed deck by a f i r m of local roofing c o n t r a c t o r s .

Roof No. 1 : L a s t -0 -Roof

This s y s t e m i s composed of a p ~ l ~ i s o b u t y l e n e sheet bonded to a supporting reinforcement made of an elastomer impregnated a s b e s t o s f e l t , This m e m b r a n e i s applied with a liquid polyisobutylene adhesive, s p r e a d in ribbons. The laps a r e sealed with polyisobutylene adhesive filled with a s b e s t o s f i b r e s , A polyisobutylene sheet bonded t o a g l a s s - f i b r e fabric i s used for flashing and i s bonded with a t h i r d type of polyiso- butylene adhesive. A s u r f a c e finish i s applied t o the completed m e m b r a n e . T h i s finish i s an a c r y l i c latex coating and i s applied by brushing or spraying.

T h e joint between t h e plywood p a n e l s w a s t a p e d w i t h a p r e s s u r e

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s e n s i t i v e a d h e s i v e t a p e , and t h i s m a t e r i a l w a s a l s o u s e d t o t a p e a l l knotholes and i m p e r f e c t i o n s i n t h e s u r f a c e .

Guide l i n e s f o r the ribbon a p p l i c a t i o n of t h e l a s t - o - b e s t o s c e m e n t w e r e d r a w n on the deck. The a d h e s i v e w a s applied i n $ - i n . t o

1 - i n . r i b b o n s 6 i n . a p a r t and 1 i n . f r o m the edge a t a r a t e of 3/4 gallon p e r 100 s q f t . The l a s t - o - b e s t o s m e m b r a n e w a s r o l l e d out i n t o l h e s e r i b b o n s a s F i g u r e 2 i l l u s t r a t e s . A f t e r r e m a i n i n g o v e r n i g h t the a d h e s i v e r i b b o n s w e r e s t i l l v e r y soft and had softened t h e l a s t - o - b e s t o s m e m b r a n e . The l a p c e m e n t w a s

applied along a 3 - i n . width of t h e f i r s t m e m b r a n e and l a s t - o - b e s t o s c e m e n t a g a i n applied in r i b b o n s on 6 - i n . c e n t r e s ; t h e s e c o n d half of the d e c k w a s t h e n c o v e r e d with t h e l a s t - o - b e s t o s m e m b r a n e . T h e e d g e s w e r e f l a s h e d with t h e l a s t - o - f l a s h f l a s h i n g m e m b r a n e using t h e a p p r o p r i a t e c e m e n t ( F i g u r e 3). When t h e roof w a s c o m p l e t e d , i t w a s noted t h a t the s o l v e n t s f r o m t h e a d h e s i v e s had m a d e t h e polyisobutylene s h e e t i n g v e r y s o f t . After 5 d a y s a coating of L a s t - 0 - L u m e

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white a c r y l i c l a t e x

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w a s applied o v e r the e n t i r e s u r f a c e , a t a r a t e of 2 / 3 gallon p e r 100 s q ft. T h i s coating w a s applied i n two c o a t s by b r u s h i n g , t h e f i r s t having 12 m i l s wet f i l m t h i c k n e s s and t h e s e c o n d 16 m i l s wet f i l m t h i c k n e s s . T h e c o m p l e t e d roof s a m p l e w a s exposed on 12 May 1964.

Roof No. 2: V e r a l

T h i s s y s t e m c o n s i s t s of a n a s p h a l t m e m b r a n e t h a t i s r e i n f o r c e d with a g l a s s f a b r i c and s u r f a c e d with a m e t a l foil m a d e of a l u m i n u m o r c o p p e r . The m e m b r a n e i s bonded t o a b a s e s h e e t m a d e f r o m g l a s s o r a s b e s t o s and s a t u r a t e d with a s p h a l t . T h e m a t e r i a l i s m a n u f a c t u r e d i n F r a n c e by S i p l a s t and is m a r k e t e d by L a n g l e y s of London, England.

The plywood d e c k w a s c o v e r e d with a s p h a l t - s a t u r a t e d a s b e s t o s f e l t and n a i l e d a t 6 - i n . i n t e r v a l s . In o r d e r t o obtain a n a d e q u a t e bond t o t h e f e l t , the a s p h a l t on t h e u n d e r s i d e of t h e V e r a l w a s h e a t e d with an a i r - a c e t y l e n e t o r c h u n t i l i t g l i s t e n e d . I t w a s noted t h a t any o v e r h e a t i n g c a u s e d t h e a s p h a l t t o flow. T h i s o p e r a t i o n i s v e r y s l o w and 2 h r w e r e r e q u i r e d t o apply a s h e e t

1 2 ft long. An a l t e r n a t i v e method of a p p l i c a t i o n is t o m o p on hot a s p h a l t , but t h i s w a s not convenient i n t h e l a b o r a t o r y a p p l i c a t i o n of t h i s m a t e r i a l . The r e l e a s e p a p e r f r o m the s e l v a g e edge of the

V e r a l s h e e t w a s r e m o v e d , and t h e s e l v a g e w a s s e c u r e d w i t h n a i l s 2 in. f r o m t h e edge of the s e l v a g e and 4 in. a p a r t and a second r o w s t a g g e r e d f r o m t h e f i r s t and 3 i n . f r o m t h e e d g e . T h e second s h e e t of V e r a l w a s t h e n applied t o c o v e r t h e

s e l v a g e ( F i g u r e 4 ) . T h e e d g e s w e r e f l a s h e d with t h e s a m e m a t e r i a l t o p r o d u c e t h e c o m p l e t e d roof which w a s exposed on 1 5 May 1964.

Roof No. 3: B l a c k - B u t y l M e m b r a n e

T h i s i s a m e m b r a n e in s h e e t f o r m f o r s i n g l e - p l y roofing; the butyl m a t e r i a l i s a c o p o l y m e r of isobutylene and i s o p r e n e p r o d u c e d by t h e P o l y m e r C o r p o r a t i o n . The i s o p r e n e content i s v e r y low r a n g i n g f r o m 0.7 t o 3. 0 m o l p e r c e n t . The vulcanized m e m b r a n e i s m a n u f a c t u r e d by M i n e r Rubber Company. It i s compounded with c h e m i c a l a d d i t i v e s t o r e s i s t ozone and t h e w e a t h e r and t o have high e l a s t i c i t y . T h e s h e e t m e m b r a n e i s applied t o a s u b s t r a t e w i t h a c o n t a c t - t y p e a d h e s i v e .

T h e b u t y l - r u b b e r m e m b r a n e w a s cut and l a i d along t h e 12-ft l e n g t h of t h e roof and allowed t o r e l a x . T h e butyl s h e e t w a s folded o v e r onto i t s e l f along t h e long d i m e n s i o n and a c o n t a c t - type c e m e n t a p p l i e d o v e r the m e m b r a n e and t h e d e c k u s i n g a r o l l e r ( F i g u r e 5). T h e a d h e s i v e u s e d w a s l a b e l l e d 3-M 1870 and w a s m a n u f a c t u r e d by the Minnesota Mining and M a n u f a c t u r i n g Company. A f t e r t h e a d h e s i v e w a s " d r y - t o - t o u c h " , t h e r u b b e r

s h e e t w a s unfolded and t h e a d h e s i v e bond c o n s o l i d a t e d by s m o o t h i n g t h e s u r f a c e of t h e butyl m e m b r a n e with a r o l l e r . C a r e w a s t a k e n

t h a t no t e n s i o n w a s in t h e m e m b r a n e . T h e s e c o n d half of the m e m b r a n e w a s then folded b a c k onto t h e c e m e n t e d p o r t i o n , and a d h e s i v e w a s

applied t o t h e d e c k and m e m b r a n e u s i n g t h e s a m e p r o c e d u r e a s b e f o r e . T h e s e c o n d s h e e t of butyl r u b b e r w a s a d h e r e d u s i n g t h i s p r o c e d u r e and lapped o v e r t h e f i r s t s h e e t t o give a 4 - i n . o v e r l a p . T h e e d g e s w e r e f l a s h e d with t h e s a m e butyl r u b b e r . The completed roof w a s e x p o s e d on 20 May 1964.

Roof No. 4: White -Butvl M e m b r a n e

T h i s m a t e r i a l w a s a p p l i e d i n t h e s a m e m a n n e r a s roof No. 3 u s i n g t h e s a m e a d h e s i v e . T h e completed roof w a s exposed on 2 0 May 1964.

Roof No. 5: Neoprene-Hypalon Roofing

T h i s i s a liquid-applied roofing. The roof is fir s t p r i m e d with neoprene and then coated with two l a y e r s of n e o p r e n e , which w a s one of the f i r s t synthetic r u b b e r s t o be produced on a

c o m m e r c i a l s c a l e . It w a s introduced in 1932 and i s r e p o r t e d t o have a h i s t o r y of good r e s i s t a n c e t o sunlight, t e m p e r a t u r e e x t r e m e s , w e a t h e r , ozone and t o oil and g r e a s e . The n e o p r e n e f i l m i s coated with two l a y e r s of hypalon, which w a s introduced in 1952 and h a s t h e c h e m i c a l n a m e of chlorosulphonated polyethylene. The hypalon i s produced by t r e a t i n g a solution of polyethylene with g a s e o u s c h l o r i n e and sulphur dioxide. Hypalon i s r e p o r t e d t o have the s a m e d e s i r a b l e p r o p e r t i e s a s n e o p r e n e and, in addition, can be tinted t o p r o d u c e s t a b l e c o l o u r s . Although t h e s y s t e m u s u a l l y u s e s n e o p r e n e and hypalon i n combination, they m a y be u s e d singly. The application p r o c e d u r e i s usually with a liquid solution, but c u r e d s h e e t s have a l s o been u s e d having a n e o p r e n e c e m e n t a s t h e

a d h e s i v e

.

The fluid -applied s y s t e m u s e s the conventional a p p l i

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cation methods of brushing, rolling, o r s p r a y i n g , and i t i s

r e p o r t e d that t h e p r e s s u r e - f e d r o l l e r i s t h e m o s t economical and s a t i s f a c t o r y method. The t o t a l t h i c k n e s s of t h e f i n i s h e d d r y f i l m should be a t l e a s t 20 m i l s (0. 020 in. ).

The n e o p r e n e and hypalon p o l y m e r s a r e produced by DuPont and t h e n f o r m u l a t e d into t h e roof s y s t e m s by v a r i o u s m a n u f a c t u r e r s . T h e s y s t e m u s e d i n t h i s c a s e w a s t h a t of t h e B o r d e n C h e m i c a l Company and i s m a r k e t e d a s C o l o r d u r .

T h e d e c k w a s p r i m e d with the n e o p r e n e p r i m e r , which i s a solution of n e o p r e n e t h a t h a s had t h e v i s c o s i t y r e d u c e d by t h e addition of m o r e xylene solvent. When t h i s w a s d r y , a l l t h e joints and f l a s h i n g s of the roof d e c k w e r e taped with a p r e s s u r e

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s e n s i t i v e cotton tape. T h e t a p e s w e r e coated with a n e o p r e n e solution,

C o l o r d u r No. 2146-6, with c o v e r a g e extending a t l e a s t 4 i n . f r o m the t a p e . After 2 h r t h e f i r s t c o a t of n e o p r e n e w a s applied by b r u s h and r o l l e r with a wet f i l m t h i c k n e s s of 8 m i l s ( 0 . 0 0 8 in. ). After waiting f o r a n o t h e r 3 h r , a second application of n e o p r e n e w a s r c l l e d on with a wet f i l m t h i c k n e s s of 8 t o 10 m i l s (0.008 t o

0.010 i n . ) . The amount of n e o p r e n e u s e d in t h e s e applications w a s applied a t a r a t e of 2$ gallons p e r 100 s q ft. After drying overnight, the f i r s t coat of hypalon ( C o l o r d u r No. 2146-7A) w a s applied by r o l l e r t o produce a wet f i l m t h i c k n e s s of about 8 m i l s (0.008 i n . ). It w a s noticed t h a t i f the hypalon is r o l l e d out too much, the n e o p r e n e "bleeds through" t h e hypalon. Consequently,

i t i s difficult t o p r o d u c e a u n i f o r m a p p l i c a t i o n and a f t e r t h e f i r s t c o a t of hypalon t h e roof a p p e a r e d v e r y p a t c h y . A f t e r 4 h r , a s e c o n d c o a t of hypalon w a s a p p l i e d i n a wet f i l m t h i c k n e s s of 10 m i l s ( 0 . 01 0 i n . ). T h e a m o u n t of hypalon applied in t h e s e two c o a t s w a s a t a r a t e of 1; g a l l o n s p e r 100 sq ft. A f t e r c u r i n g o v e r n i g h t i t w a s noted t h a t s e v e r a l s h r i n k a g e c r a c k s had d e v e l o p e d i n t h e hypalon s u r f a c i n g , p a r t i c u l a r l y at t h e e d g e s and o v e r t h e joint in the plywood ( F i g u r e

6 ) .

T h e t a p e s a t t h e c a n t w e r e a l s o u n d e r t e n s i o n and had p a r t i a l l y pulled a w a y f r o m i t . T h e s e c r a c k s d i d not a p p e a r t o p e n e t r a t e t h r o u g h t h e n e o p r e n e coating and the roof w a s e x p o s e d on 25 May 1964. Roof No.

6:

S i l i c o n e - R u b b e r Roofing

T h i s i s a l i q u i d - a p p l i e d s y s t e m . T h e r u b b e r i s a t w o - c o m p o n e n t s y s t e m , t h e c u r i n g a g e n t being added t o t h e

liquid r u b b e r i m m e d i a t e l y p r i o r t o the a p p l i c a t i o n of t h e r o o f i n g . T h e s i l i c o n e r u b b e r s have a r e c o r d of low w a t e r a b s o r p t i o n , high t h e r m a l conductivity, high ozone r e s i s t a n c e and a low c o e f f i c i e n t of t h e r m a l e x p a n s i o n . T h e y a l s o have a high m o i s t u r e v a p o u r t r a n s m i s s i o n and low t e n s i l e s t r e n g t h which s t i l l m a k e s i l i c o n e r u b b e r s a n e x p e r i m e n t a l roof. A a l a s s - f a b r i c r e i n f o r c e d s i l i c o n e s h e e t i s a l s o being e x a m i n e d f o r p o s s i b l e u s e a s a roof m e m b r a n e . T h e m a t e r i a l s f o r t h i s roof s a m p l e w e r e obtained f r o m t h e G e n e r a l E l e c t r i c Company. T h e s e m a t e r i a l s w e r e a p r i m e r , s i l i c o n e r u b b e r roofing and c u r i n g a g e n t , c a u l k i n g , a s a m p l e of g l a s s - f a b r i c r e i n f o r c e d s i l i c o n e s h e e t i n g and a n a d h e s i v e f o r t h i s s h e e t i n g . A 3- x 3-ft p i e c e of s h e e t i n g w a s a p p l i e d t o t h e d e c k u s i n g t h e c o n t a c t - t y p e a d h e s i v e , which w a s s u p p l i e d and i d e n t i f i e d a s SR-585. T h e r e m a i n d e r of t h e roof and a l l e d g e s a s well a s t h e c a n t s t r i p w e r e c o a t e d with a s i l i c o n e p r i m e r i d e n t i f i e d a s

SS4044. All j o i n t s w e r e t h e n s e a l e d with a s i l i c o n e - r u b b e r caulking m a t e r i a l . A m i x t u r e of s i l i c o n e r u b b e r w a s p r e p a r e d f r o m 40 p a r t s of XE1043 m a t e r i a l with 1 p a r t of c a t a l y s t SS4093C. A f t e r a p p l i - c a t i o n of t h i s m a t e r i a l , which bad a v e r y s m o o t h c o n s i s t e n c y , t h e roof w a s allowed t o c u r e o v e r n i g h t . A s e c o n d m i x t u r e of t h e

m a t e r i a l s w a s then p r e p a r e d and a p p l i e d by r o l l e r and the s u r f a c e s m o o t h e d by b r u s h i n g . After the second coat w a s c u r e d the s u r f a c e w a s d u s t e d with fine m i c a and t h e roof e x p o s e d on 27 May 1964.

Roof No. 7 : Cold - P r o c e s s Asphalt Roofing

T h e c o l d - p r o c e s s roof s y s t e m u s e s roofing f e l t s , cold -applied solvent adhesives and cold -applied emulsions in a s i m i l a r manner to the u s e of hot -applied bitumens in t h e p r e p a - ration of built-up roofing. The emulsions a r e v e r y s m a l l

droplets of bitumen in water and a r e stabilized by the addition of a m a t e r i a l with s m a l l p l a t e - l i k e p a r t i c l e s . When the emulsion c u r e s , the p a r t i c l e s f o r m a honeycorrib network throughout the film and produce a stable film that enables t h e u s e of soft asphalts with excellent weathering c h a r a c t e r i s t i c s . Bentonite clay i s the principal stabilizer used in asphalt roofing emulsions. The

emulsions a r e a l s o capable of being reinforced by incorporating f i b r o u s m a t e r i a l such a s a s b e s t o s in the emulsion or by applying chopped g l a s s f i b r e s using a s p r a y technique. The c u r e d emulsion film does not r e q u i r e any s u r f a c e covering, but i t s weathering c h a r a c t e r i s t i c s can b e improved by a light-reflective coating t o reduce s u r f a c e t e m p e r a t u r e s and t h e r m a l movements. As the emulsions contain w a t e r , they can only be applied a t t e m p e r a t u r e s above freezing and because the m a t e r i a l is f a i r l y slow to c u r e , t h e r e i s a danger of wash-off during the f i r s t day or two a f t e r application.

The s y s t e m used on the s a m p l e deck was that of a t h r e e -ply c o l d - p r o c e s s built -up roofing using 53 -1b s a t u r a t e d and coated f e l t s and a top coat of asphalt emulsion. All m a t e r i a l s used w e r e manufactured and m a r k e t e d by the Flintkote Company of Canada Limited.

F o u r t e e n - f t lengths of 53-lb s a t u r a t e d and coated f e l t s w e r e cut and allowed to lie flat for about 18 h r . The f i r s t s t r i p of felt was applied 12 in. f r o m the cant s t r i p , nailed t o it on 8 -in. c e n t r e s and fastened over and around the cant. One quart of cold- p r o c e s s cement adhesive was applied over this nailed felt and a

second 53 -1b felt was applied to extend t o 2 ft f r o m the cant s t r i p . T h e portion of the felt that was over the plywood was nailed on 12 -in. c e n t r e s . T h e felt was not extended up the cant s t r i p because of difficulties with the rigidity of the felt and the s m a l l

s i z e of the cant s t r i p . It was decided to complete this cant s t r i p with g l a s s f a b r i c and asphalt emulsion. Two q u a r t s of cold- p r o c e s s cement adhesive w e r e applied over this. A third sheet

w a s r e p e a t e d u n t i l a 3 - p l y roof of 53-lb s a t u r a t e d and c o a t e d f e l t s w a s o b t a i n e d . T h e e d g e s w e r e f l a s h e d by e m b e d d i n g g l a s s f a b r i c i n type 5 a s p h a l t e m u l s i o n , u s i n g 3 p l i e s of g l a s s f a b r i c a s shown in F i g u r e 7 . L a s t l y , 2 g a l l o n s of a s p h a l t e m u l s i o n w e r e a p p l i e d o v e r t h e e n t i r e s u r f a c e t o p r o d u c e a f i n a l product. A f t e r 24 h r c u r i n g , t h e roof w a s e x p o s e d on 29 M a y 1964. Roof No. 8: T / N A 200 T h i s i s a s i n g l e - p l y roof s y s t e m . It h a s a 2 m i l t h i c k polyvinyl f l u o r i d e f i l m , f a c t o r y l a m i n a t e d with a n a d h e s i v e t o a n a s b e s t o s felt i m p r e g n a t e d with a n e o p r e n e l a t e x . F o r u s e a s roofing t h i s m e m b r a n e i s a p p l i e d u s i n g conventional hot o r cold a s p h a l t a d h e s i v e s . T h e m a t e r i a l i s 36 i n . wide and h a s a 2 - i n . s e l v a g e edge f o r s i d e lapping. A f t e r bonding, t h e s i d e l a p s a r e s e c u r e d with a 2 i n . wide p r e s s u r e - s e n s i t i v e t a p e of polyvinyl f l u o r i d e f i l m . T h e high c o e f f i c i e n t of s o l a r r e f l e c - t i v i t y c o n s i d e r a b l y r e d u c e s s u r f a c e t e m p e r a t u r e and s o g r e a t l y r e d u c e s t h e p o s s i b i l i t y of s l i p p a g e on s t e e p s u r f a c e s . In m a n y c a s e s , t h e m e m b r a n e is a p p l i e d o v e r a c o a t e d a s p h a l t b a s e s h e e t . T h e m a t e r i a l s f o r t h i s roofing s y s t e m w e r e s u p p l i e d by Building P r o d u c t s L i m i t e d . A 53-lb s a t u r a t e d and c o a t e d b a s e s h e e t w a s a d h e r e d t o t h e d e c k with an a s p h a l t c o l d - p r o c e s s c e m e n t with a 4 - i n . l a p . T h e s h e e t w a s s e c u r e d t o t h e d e c k and c a n t s t r i p with n a i l s on 1 2 - i n . c e n t r e s .

T h e T/NA 200 w a s a d h e r e d t o the b a s e s h e e t with t h e s a m e c o l d - p r o c e s s c e m e n t . T h e s e c o n d s h e e t w a s l a i d with a 4 - i n . l a p u s i n g t h e s a m e a d h e s i v e . T h e a d h e s i v e w a s a p p l i e d up t o 1 i n . f r o m the l a p l i n e and t h e m e m b r a n e r o l l e d i n . T h e edge w a s f i n i s h e d w i t h t h e p r e s s u r e

-

s e n s i t i v e polyvinyl f l u o r i d e t a p e . T h e e d g e s of t h e roof w e r e f i n i s h e d by folding t h e m e m b r a n e u n d e r and t h e n t a p e d w i t h the p r e s s u r e - s e n s i t i v e t a p e .

Roof No. 9: B u t y l L a t e x with Hypalon F i n i s h

T h i s i s a l i q u i d - a p p l i e d roofing s y s t e m t h a t i s a p p l i e d b y t h e conventional t e c h n i q u e s of s p r a y o r r o l l e r c o a t i n g . A lightweight f i b r e g l a s s s c r i m i s u s e d t o add

s t r e n g t h t o t h e c u r e d f i l m , and a t o p c o a t i n g of c h l o r o s u l p h o - n a t e d polyethylene (hypalon) i s u s e d t o p r o v i d e p r o t e c t i o n f r o m

d i r t accumulation. The m a t e r i a l s f o r t h i s s a m p l e roof w e r e supplied by Enjay L a b o r a t o r i e s and consisted of a butyl-latex sample coded 3305-6-1, a s a m p l e of hypalon top coat and a piece of f i b r e g l a s s m a t type 1 5 L manufactured by Johns

-

Manville Corporation.

An anchor coat of butyl l a t e x with 10 t o 15 m i l s wet film thickness was applied t o the roof deck, and while s t i l l wet t h e g l a s s s c r i m was laid in and rolled. A s m a l l amount of butyl l a t e x was then applied to wet t h e g l a s s s c r i m . The edges and cant s t r i p w e r e flashed with g l a s s s c r i m embedded in butyl latex. After drying for 3 h r , a coat of butyl l a t e x was applied using a wet film thickness of 12 m i l s . Two h r l a t e r , a second coat of butyl l a t e x was applied with 1 5 m i l s wet f i l m thickness. A t h i r d coating of butyl l a t e x w a s applied, again with 15 m i l s wet film thickness, after about 72 h r . After curing, a coat of hypalon with a wet film thickness of 12 m i l s w a s applied over half of the sample roof. The completed roof shown i n F i g u r e

8 was exposed on 16 June 1964.

Roof No. 10 : Conventional Hot Asphalt Built -Up Roofing

T h i s type of roofing h a s been in u s e f o r about a hundred y e a r s and m o s t of the non-domestic roofs a r e of t h i s type. The built-up m e m b r a n e c o n s i s t s of p l i e s or l a y e r s of roofing felt bonded together with hot bitumen on site. It i s laid t o conform t o t h e roof deck and t o produce a flexible waterproof m e m b r a n e . The roofing f e l t s consist of a m a t of organic or inorganic f i b r e s , impregnated o r s a t u r a t e d and s o m e t i m e s coated with bitumen. The m o s t common a r e t h e organic r a g felts now made l a r g e l y f r o m wood f i b r e pulp t o which i s added s c r a p paper and a s m a l l p e r c e n t a g e of rag. Inorganic a s b e s t o s -fibre felts have a l s o been i n u s e f o r many y e a r s and, m o r e recently, asphalt -impregnated g l a s s - f i b r e felts have been used.

Two types of bitumens a r e used: a s p h a l t s and coal t a r pitch. Most of t h e asphalt used i n Canada a s an impregnating and waterproofing agent in asphalt roofing products and built-up roofing i s the r e s i d u e of p e t r o l e u m

distillation, with s o m e modifications t o achieve d e s i r a b l e p r o p e r t i e s and a r a n g e of softening points.

The s a m p l e roof w a s c o n s t r u c t e d on the s i t e using a s p h a l t a s t h e waterproofing bitumen with a s p h a l t - s a t u r a t e d r a g felts. The roof w a s i n s t a l l e d by a l o c a l f i r m of roofing c o n t r a c t o r s . T h e f i r s t two p l i e s w e r e nailed to the deck without adhesive. Two p l i e s w e r e a d h e r e d t o t h e s e f e l t s using hot a s p h a l t . The cant s t r i p w a s a l s o c o v e r e d with felt,

and a cold-applied p l a s t i c c e m e n t w a s s p r e a d o v e r the cant s t r i p . The m e t a l flashing was i n s t a l l e d and r a g felt mopped o v e r t h i s flashing. F i n a l l y a top pour coat w a s s p r e a d o v e r the e n t i r e roof s a m p l e and g r a v e l s p r e a d onto t h i s hot a s p h a l t ( F i g u r e 9 ) . T h i s roof w a s i n s t a l l e d on

2 3

June 1964.

The roof s a m p l e s w e r e i n s t a l l e d t o t h e "Bailey Bridge" s t r u c t u r e ( F i g u r e 10). It will be noted that 12 panels a r e exposed. T e n of t h e s e panels a r e t h o s e d e s c r i b e d i n t h i s r e p o r t and two a r e panels t h a t a r e a t the moment c o v e r e d with a s p h a l t r o l l roofing which can be r e p l a c e d o r covered with o t h e r roof s y s t e m s i f r e q u i r e d .

EXAMINATION O F ROOF SAMPLES A F T E R ONE YEAR OF

EXPOSURE

Roof No. 1: L a s t - 0 - R o o f

1. After 2 months, b l i s t e r s developed on t h e flashing m a t e r i a l and a b l i s t e r f o r m e d o v e r the joint i n the plywood deck.

2 . _After 4 m o n t h s , t h e r e w a s s o m e staining o v e r t h e a d h e s i v e r i b b o n s and the m a t e r i a l pulled away f r o m t h e cant s t r i p .

3.

A f t e r

6

months, c r a c k s a p p e a r e d o v e r nailheads i n the panel. 4. After 8 m o n t h s , the c r a c k s w e r e o v e r the e n t i r e s u r f a c e

and a p p e a r e d t o be r a n d o m , with about 2 i n . between e a c h

c r a c k . D i r t retention in the c r a c k s m a k e s t h e m v e r y a p p a r e n t .

5.

No f u r t h e r c r a c k i n g had a p p e a r e d a f t e r 12 months. T h e s e c r a c k s do not a p p e a r t o p e n e t r a t e through the polyisobutylene s h e e t . Figlrre 11 i s a c l o s e - u p of t h e c r a c k s a f t e r 1 y e a r .

Roof No. 2 : Vera1

1. After 12 months, t h e r e is s o m e s u r f a c e dulling of t h e aluminum. T h e exposed asphalt a t t h e l a p s

is

hardened, and s o m e of t h e reinforcing g l a s s f a b r i c h a s become

exposed at t h e s e locations.

Roof No. 3 : Black-Butvl Membrane

1. After 2 months, the exposed e x c e s s adhesive turned brown.

2. After 10 months, t h e l a p joint l i f t e d a l i t t l e .

3 , After 12 months, t h e r e w a s v e r y little change except f o r

s o m e ponding of water on the roof.

Roof No. 4: White -Butvl Membrane

1. After 2 months, the m a t e r i a l s t a r t e d t o develop slight chalking.

2. After 4 months, chalking was v e r y pronounced.

3 . After

6

months, chalking was washing over t h e edge of t h e roofing.

4. After 1 2 months, t h e amount of chalking that h a s taken place i s shown in F i g u r e 1 2 .

Roof No.

5

: Neoprene -Hypalon

1. After 12 months, t h e cracking that had developed in t h e roof m e m b r a n e before exposure did not appear t o have p r o g r e s s e d any f u r t h e r .

Roof No.

6:

Silicone Rubber

1. After 2 months, t h e sheet -applied m a t e r i a l had high d i r t retention and s o m e blistering. The liquid-applied

m a t e r i a l did not appear t o show any change.

2. After

6

months, the e n t i r e roofing (sheet-applied and liquid-applied) had a high dirt retention.

3. _{After 12 months, d i r t retention is v e r y s e v e r e .}

Roof No. 7 : C o l d - P r o c e s s A s ~ h a l t Roofing

1. After 2 months, brown p a t c h e s a p p e a r e d on t h e s u r f a c e with one s m a l l s u r f a c e c r a c k .

2. After 4 months, t h e r e w e r e s e v e r a l s m a l l s u r f a c e pin-holes and s o m e s u r f a c e chalking.

3. After 12 months, s o m e dusting of t h e s u r f a c e was noted.

Roof No.

8 :

T/NA 200

1. A f t e r 2 months, t h e r e was a slight shrinkage of the tape.

2. No F u r t h e r visible changes w e r e evident a f t e r 12 months.

Roof No.

9 :

Butyl Latex with Hypalon F i n i s h

1. After 2 months, t h e portion not c o v e r e d with hypalon showed d i r t retention.

2. After 4 months, the butyl l a t e x portion had a v e r y high d i r t retention and t h e g l a s s s c r i m on t h e cant s t r i p had pulled away f r o m the cant.

3.

After 12 months, t h e r e i s s o m e f r a c t u r e of t h e butyl-latex glass - s c r i m m e m b r a n e a t t h e edge w h e r e t h e r e h a s been a lot of traffic. F i g u r e 1 3 shows t h e two p o r t i o n s of t h i s roof a f t e r 12 months of exposure.

Roof No. 10: Hot -Applied Asphalt-Rag Built -Up Roofing

1. A f t e r 2 months, t h e r e was s o m e g r a v e l blow -off and s o m e asphalt bubbled through t h e gravel.

2. After 4 months, t h e r e was s o m e ponding a t the front portion of t h e s a m p l e roof.

CONCLUSION

Many of t h e new s y s t e m s appear t o have advantages over conventional bituminous roofing f o r c e r t a i n types of

roofing. The omission of g r a v e l f r o m t h e s u r f a c e of t h e s e new roofing s y s t e m s simplifies t h e inspection and maintenance of the roof. The exposure conditions of t h e s e s y s t e m s a r e not t r u l y r e p r e s e n t a t i v e of field exposure because the roofing does not enclose a heated space. T h e deck i s a l s o of a v e r y lightweight m a t e r i a l and s o subjects the roofing t o a g r e a t e r deflection than would be normal. The s a m p l e s a r e exposed in a n e a r l y flat condition and, in s o m e c a s e s , ponding t a k e s place. No attempt h a s been made t o prevent traffic on t h e s e decks, and a l a r g e number of v i s i t o r s have walked over them.

Two considerations in which designers and owners a r e p a r t i c u l a r l y i n t e r e s t e d a r e the cost of t h e m a t e r i a l and t h e t i m e required for application. It was not possible t o make a

cost comparison for t h e s e m a t e r i a l s because many of the

s a m p l e s a r e considered by t h e m a n u f a c t u r e r s t o be experimental. Other manufacturers would not s e l l t h e m a t e r i a l but provided s a m p l e s f r e e of charge.

In considering the t i m e f o r application, i t should be pointed out that only one of t h e roofs was applied by r o o f e r s , and the inexperience of the technical staff in this field caused difficulties and delays in t h e installation of s o m e of the s y s t e m s . Some of the s y s t e m s on t h e other hand w e r e easily applied, but it was decided that an installation-time comparison would n o t b e of much information because of the c i r c u m s t a n c e s involved. The r e p o r t gives a complete documentation of the m a t e r i a l s , t h e i r application t o t h e deck and t h e i r p e r f o r m a n c e a f t e r one year of exposure in Ottawa.

T A B L E

I

TYPES O F R O O F SYSTEMS USED IN EXPOSURE PROGRAM

Roof No. 1, 2, Type of S y s t e m L a s t -0 -Roof Vera1 Black-Butyl M e m b r a n e White -Butyl M e m b r a n e N e o p r e n e -Hypalon Silicone R u b b e r

Cold - P r o c e s s Asphalt Roofing T/NA 2 0 0

Butyl L a t e x with Hypalon F i n i s h Hot Asphalt Built -Up Roofing

M a n u f a c t u r e r Johns -Manville Langleys M i n e r R u b b e r Co. M i n e r R u b b e r Co. Borden C h e m i c a l Co. G e n e r a l E l e c t r i c Flint kot e Building P r o d u c t s E n j a y L a b o r a t o r i e s Local c o n t r a c t o r

Cant strip

2"

-J-A

/

r><lw

I

I

F I G U R E

1

S H I N G L E T Y P E L A P P I N G O F R O O F P A N E L S

F i g u r e 3 Flashing E a s t - 0 - B e s t a s Roof.

Figrare 5 Applying Contact Cement f o r Butyl Roofing.

F i g u r e 7 IanstalSatio~s of _{F l a s h i n g t o C o l d - P r o c e s s Roofing.}

F i g u r e 8 _{Completed Butyl -Eat e x Roofing, One}

_Half

F i g u r e

9

_{Applying Gravel t o Hot Built-up Roofing.}

F i g u r e

B

h Cracks on East-O-Roof after h 2 Months' E x p o s u r e ,

F i g u r e

B

2 _{Chalking sf W h i t e Butyl a f t e r 1 2 Monthsg}

F i g u ~ e 1 3 Butyl-Latex Roofing a f t e r 1 2 Monthst Exposure