Publisher’s version / Version de l'éditeur:
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la
première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
Building Note (National Research Council of Canada. Division of Building Research), 1957-07-01
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.
https://nrc-publications.canada.ca/eng/copyright
NRC Publications Archive Record / Notice des Archives des publications du CNRC : https://nrc-publications.canada.ca/eng/view/object/?id=295f55af-9cfb-4e37-bf46-b2789edfddc3 https://publications-cnrc.canada.ca/fra/voir/objet/?id=295f55af-9cfb-4e37-bf46-b2789edfddc3
NRC Publications Archive
Archives des publications du CNRC
This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at
Repairing leaky masonry walls
Ser Tm B92 no. 29 c . 2 BLDC;
REPAIRING mAHY MASONRY WALLS
H,
Brian DickenaDZC
23B57
<
2 9 .!-- 7 " #i'
.! REPAIRING LEAKY MASONRY WALLS
6
by
He BpIan Dickens
Moisture may e n t e r a masonry w a l l i n a v a r i e t y of wayso Before proceeding w i t h a n e x t e n s i v e r e p a i r program i t i s a d v i s a b l e t o check c a r e f u l l y around a l l window and door openings and
a t
copfng and f l a s h i n g s t o s e e whether moisture may be e n t e r i n g a t t h e s e p o i n t s o If t h e r e i s any evidence of c r a c k s o r openings
a t s u c h l o c a t i o n s t h e s e should be p r o p e r l y caulked and s e a l e d e Leakage o c c m r i n g a f t e r t h e s e measures have been taken
i s l i k e l y t o be due t o f a u l t y r n o r t a ~ jo i n t s o r i n some c a s e s t o a h i g h l y porous type of b p i c k o r b l o c k ,
Repointing o f Mortar J o f n t s
Where t h e m o r t a r j o i n t s a r e s u s p e c t e d t h e most e f f e c t i v e remedy c o n s i s t s of r e p o i n t i n g the f a c e j o i n t s o This e n t a i l s c u t t i n g o r r a k f n g o u t t h e o l d m o r t a r t o a d e p t h of
3/4
i n o h t o 1 inchu s i n g g r f n d f n g wheels o r pneumatic c h i s e l s , A l l l o o s e o r d i s i n t e -
g a a t e d m a t e r i a l beyond t h i s d e p t h should also be removed, After c u t t i n g , wash a 1 7 d u s t and l o o s e m a t e r i a l o u t of t h e j o i n t s w i t h a
j e t of w a t e r b
The masomy should be damp b u t n o t wet when r e p o i n t i n g is begun, The m o r % a ~ used should have a d e n s i t y no g r e a t e r than
t h e o ~ f g i n a l m o r t a ~ ~ I n t h e absence of I n f o r m a t i a n on t h e density
and p r o p o p t i o n s of t h e o l d m o r t a r a suggested mix would be:
1:1:6
cement :Ifme :sand (by volume1
f o r c l a y masonry,1:2:8 o r
9
eement:l9rne:sand ( b y v o l m ) f o r c o n c r e t e and sand-191ne produe t sT h e new j o f n t s should be packed t i g h t l y and concave t o o l e d w i t h a rounded bar0
Grouting of Moptar J o i n t s
A l e s s expensive method o f w a t e r p r o o f i n g l e a k y w a l l s and one shown t o be e f f e c t i v e d m i n g t e s t s a t t h e U , S o N a t i o n a l Bureau of S t a n d a r d s c o n s i s t s of scrubbing a cement g r o u t i n t o the mortar
j o i n t s , I n applying t h e g r o u t t o t h e mortar j o i n t a template should be used t o p r o t e c t t h e a d j a c e n t masonry from d i s c o l o r a t i o n e The g r o u t should be brushed i n t o t h e dampened r n o r t a ~ joint with a s t i f f
- 2 -
The g r o u t mixture recommended 1s 1 p a r t cement, 0c25 p a r t s h y d r a t e d lime a n d 2 p a r t s f f n e sand p a s s i n g a
Noe 30 s i e v e (by volume),
/
/.' C ~ a c k s i n t h e masonry uniZs themselves can be filled w l % h t h e same m i x t u r e , The r e p o i n t i n g o r g r o u t i n g of t h e f a c e j o i n t s h a s tihe advantage of not a l t e r i n g t h e appearance of %he f i n i s h e d w a l l ,
Cement-water P a i n t s
V ' e m changing t h e appearance of t h e w a l l i s n o t objec- t i o n a b l e , an a p p l i c a t i o n of cement-water p a i n t may be used
t o
improve t h e moisture r e s i s t a n c e of the w a l l , T e s k s c a r r f e d out by the U,S, N a t t o n a l Bureau of S t a n d a r d s on w a l l s subjected t o
heavy wind-driven r a i n show t h a t cement-water p a i n t when p r o p e r l y a p p l i e d can make a w a l l h f g h l y r e s i s t a n t t o w a t e r p e n e k r a t i o n .
It was a l s o shown t h a t t h e cement-water p a i n t t e n d s t o i n c r e a s e
fn
e f f e c t i v e n e s s a s t h e r e s u l t of weathering.The application of cement-water p a i n t should c o n s i s t of ,
two b ~ u s h e d - o n c o a t i n g s , E l t h e r factory-made o r job-prepared p a f n t s may be used a l t h o u g h comrnercfal p a i n t s a r e c o n s i d e r e d more f i n e l y ground and a r e l f k e l y t o g i v e a more u n t f o m c o l o w where t i n t e d p a i n t s a r e d e s i r e d ,
A job-mixed p a i n t h a v i n g e x c e l l e n t w a t e r p r o o f i n g q u a l i t f e s may be made from e i t h e ~ w h i t e o r grey P o r t l a n d cement, Hydrated
lime n o t exeeed-lng 20 p e r c e n t by wefght of p o r t l a n d cement may be added f f d e s P ~ e d o The o p a c i t y o r hiding power of paint made from p o r t l a n d cement, may be i n c r e a s e d by t h e a d d f t i o a of
3
t o5
p e r c e n t by wefght of e i t h e r tftanBemx d f s x f d e o r z i n c s u l p h f d e oThe p ~ e p a r a tlon of t,he surface and t h e teehnfque of
mfxfng and a p p l y i n g t h e p a f n t s a r e t h e most important f a o t o r s a f f e c t i n g t h e d u r a b i l ' l t y and e f f e e t ? t v e n e s s of t h e @oat'lnga The walls should be c l e a n and f ~ e e of l o o s e p a r t i c l e s of moptap, gpease, and waxo Grease o r o f 1 can sometfmes be removed by scrubbfng w S t h l y e s o l u t i o n OP a f e w ounces of t r % s o d f m phosphate t o a g a l l o n of w a t e r * The w a l l must be thoroughly r f n s e d w i t h ' w a t e r t o pernova
a l l traces of these s o l u t f o n s b e f o ~ e p a f n t i n g o The w a l l should be
l i g h t l y dampened u s i n g a horse with a fine f o g n o z z l e , It is
i m p o ~ t a n t t h a t t h e masonry a b s o ~ b l f t t l e o r no water from t h e wet p a l n t ; a l s o t h e paSnt should n o t be thfnned by drops of water
s t a n d f n g on t h e surface, The pafne should have the c o n s i s t e n c y of r i c h cream b u t a s l i g h t l y t h f m e ~ c o n s i s t e n c y may be used f o r the
f i r s t c o a t l n g on w a l l s o f c o n c r e t e w f t s , The amount of water per t e n pounds of d ~ y powder may range from 3,25 t o
4075
q u a r t s f o r eommereial p a i n t s and from 2,75 t o 3,75 q u a r t s f o r jab-mixed p a i n t s ,Frequent s t f r r f n g of t h e p a i n t i s e s s e n t d a l t o keep t h e p a i n t powder i n suspension, The p a i n t should be a p p l i e d by
serubblng i t i n t o t h e masomy with scrub o r f e n d e r brushes having
s t i l f f i b r e b r l s t l e a n o t over two fnehes l o n g a Mortar j o i n t s should be a i n t e d ' f f r s t , The f i r s t c o a t should be k e p t damp f o r a t l e a s e 2 e hours
,
When f t has hardened s u P f i c i e n t l y the wallshould be dampened a g a i n and the second c o a t a p p l i e d and kept
damp f o r
48
houps, R ~ o p i n g b r a s h e s maybe
used f o r p a i n t i n g smooth t e x t w e d s m f a c s s , Whitewash, o r p a i n t brushes with s o f tb r i s t l e s , should never
be
used,On rough t e x t u r e d walls, ioe,, those made of c e r t a i n t y p e s of concrete bloek, t h e base c o a t , w i t h advantage, may c o n s i s t of a mfxture of poptland cement and and well scrubbed I n t o the masonryo
The Poreland CemenL Assoefation has fasued a uaeful
ufde
to
t h e a p p l f e a t i o n of cement-water paints*It
i s entitled, gHow t o P a i n t Concrete Masonry Wallsn, and may be obtained on request from t h e Canada Cement Company,Df
s t r i c t S a l e s Off i c e s ,SO Kfng S k ~ e e t West, ToronBo, Ontaris,
Cement-wa t e r pal n t i s p a ~ t i e u l a r l y useful a s a p r o t e c e f ~ e treatment for concrete bloek masomy which g e n e r a l l y r e q u i r e s a
p r o t e c t f v e coae because %heset l a ~ g e units, due t o t h e f p detafl, of m a n u f a ~ t u ~ e , cannot always be LaSd w i t h a f u l l head j o i n t ( a vSP;al f a c t o r i n moitstme reafstanee),
Stucco CoaLSna_s
I
Stueeo Sacfngs ape also effective $n p ~ e v e n t f n g rnolstwe p e n e t r a t i o n 0% w a l l s S f they a r e e a r e f p l l y appffed and the t o p s
of the masomy w a l l s ape p r o t e c t e d by p ~ o j e e t f n g eaves o r f l a s h i n g t o prevent w a t e ~ f porn p e n e t ~ a t l n g behfnd the s t u e e s o
stucco is a p p l i e d , Partfcu3ar c a f e ehould be exercised when
applying a strong s t u c c o coating to a w a l l b u i l t of weak masonry
units such as s o f t b r i c k or units that show signs oZ deterioration, a s the f o r c e s s e t up in the drying of the stucco are l i k e l y to be s u f f i c i e n t to cause the masonry to s p a l l . Even strong paint
coatings have been known to remove part of the w a l l m a t e r i a l when they have peeled off.
If stucco is t o be used a s a protective coating far new
construction L t I s preferable to defer application until tihe masonry h a s had an opportunity to dry out a s t h e r e w i l l then be l e s s rSsk o f cracking.
Details of B ~ U F C O application are w e l l illustratsd
in
a n o t k s r publiea tlon of the Portland Cement Association e n t i t l e d
" P l a stepera f ~ a n u a l " , a1 so obtainable from the Canada Cemnt Compally,
Canada Cement Buflding, Phillips Square, Montreal, P,Qm
Silicone Water Repellents
Where mositure p e n e t r ~ t f sn of a wall 1 s due s o l e l y to
c a p i l l a r y a c t l o n through hlghly absorptive masonry units or to minute hair cracks in the w a l l , improvement nay be e f f e c t e d by the
use of the new silicone water r e p e l l e n t s r e c e n t l y introduced on the market, These c o l o u r l e s s m a t e r i a l s show promise &en used
for this purpose but they w i l l ! n o t s e a l lmge pores or cracks Tn masonrg and, t h e r e f o r e , cannot be considered e i t h e r a s substitutes
for rspointfng or poutTng or a s alternatives to dense coatlnga
of stucco or cement-water p a i n t s , They appear to have the d e s i ~ a b l e
property of adding relatively l i t t l e vapour resistance to the w a l l
but t h e i r durability cannot y e t be pxedfcted, and w a l l s t r e a t e d
wfth these m a t e r i a l s may have to be ra-done a t frequent i n t e r v a l s .
It shoula also be noted t h a t cement-water p a i n t , grout, p l a s t e r or m o r t a r m i l l ' not bond to a surface t h n t has been treated
with sillcone-type p a i n t , sfi theaa materials d e s t ~ o y the suation
q u a l i t i e s of the wall: necessary for the bonding of cement or lime a p p l i ~ a t l o n s ~ Thus silScones should only be used a f t e r t h e f l n a l
