A cavity wall of concealed bonding bricks

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A cavity wall of concealed bonding bricks

CANADA Ser TH1 392 no.

41

c . 2

A CAVITY WALL

OF

CONCEALED

BONDING BRICKS

by

T.

Ritchie

' _{- .} ' C - ,

- .

- 7 " / L s -

A CAVITY W A L L O F CONCEALED BONDING BRICKS

by

T. Ritchie

W h e n an o l d brick building in Eastview, Ontario, was being

d e m o l i s h e d it was observed that a cavity wall had been employed a n d t h a t the wall had been constructed in such a way that the bonding bricks w e r e h i d d e n from view. It is the purpose of

this

Note to r e c o r d a description of the unusual t y p e of construction that was employed.

The b u i l d i n g , a double h o u s e two s t o r e y s in height, was s i t u a t e d

at the south-east c o r n e r of Montgomery Street a n d M o n t r e a l Road

in

Eastview.

According to local residents it was about

90

y e a r s o l d and had

been

occupied

until about a year or two ago. It is u n d e r s t o o d that the automobile a g e n c y

n e x t _{door purchased the building with the intention of remodeling it to}

s e r v e as offices,

but

this plan was n o t c a r r i e d out and after s t a n d i n g e m p t y

for a y e a r o r t w o

the

building w a s taken down in September

1962.

A general view of the b u i l d i n g i n the early s t a g e s of d e m o l i t i o n is

shown

in

Eigur

e 1. T h e photograph shows

the

north a n d w e s t walls.

W A L L CONSTRUCT ION

The walls w e r e of r e d b r i c k s , trimmed with white bricks o v e r

windows and d o o r s . The south wall was the first t o be taken down a n d it was observed that the construction h e r e was a cavity wall with the t w o

wythes of brick tied together with bonding bricks l a i d at sight a n g l e s to the wall surface. The east wall was c o n s t r u c t e d in

the

s a m e way as

the south wall. Bond corzr s e s i n these walls consisted of alternate headers {bonding bricks) a n d s t r e t c h e r s along the course. The number of stretcher courses between b o n d i n g c o u r s e s varied, but w a s usually five. T h e e n d s of the b o n d i n g bricks w e r e f l u s h with the outer surface of the w a l l and s i n c e

t h e s e bricks w e r e shorter in length than the thickness of

the

wall t h e r e w a s a space b e t w e e n the inner surface of the wall and the end of the bonding brick which was f i l l e d with m o r t a r . T h e space between the wythes was

about 2 inches w i d e . T h i s type of construction

had

been observed previously in s o m e old buildings along the St. L a w r e n c e River near M o r r i s b u r g , Ontario

(DBR Technical Paper

No.

9

3 , F i g u r e 5). The walls of the Eastview

building w e r e f i n i s h e d on the i n t e r i o r surface by plastering d i r e c t l y on

the

b r i c k w o r k , and wallpaper and paint h a d been applied over the plaster. The

HIDDEN BONDING BRICKS

In the north a n d west

walls

there w e r e no bonding

bricks

to be

s e e n a n d it was not apparent u n t i l these walls were taken down that there w e r e any. They had been used,

but

in such a way as t o prevent them

from breaking the stretcher _{pattern of the brickwork. The north} and west

w a l l s of the building f a c e d the s t r e e t s and it is believed that the bonding

bricks

w e r e h i d d e n simply to give these walls a better appearance.

The bonding

bricks

were l a i d d i a g o n a l l y across the wall s o that

opposite c o r n e r s of the

brick

projected into the two wythes.

T o

permit the placing of the bonding

bricks,

corners

had

been cut from the adjacent

bricks.

O n e of the bonding bricks is s h o w n in F i g u r e

3.

The ' I f i t t i n g f b f the

bonding bricks ta the inner wythe was

not

as c a r e f u l l y done as to the outer

wythe, roba ably because t h e inner wythe was later plastered, which

concealed the rough work.

T h e bond courses of the north and west walls w e r e spaced apart vertically in the same way as the o t h e r

walls,

with five o r d i n a x y courses

separating the bond courses. The diagonal bonding

bricks

were spaced

horizontally about

30

inches along t h e course.

BRICKS

The

bricks

had been made by the soft-mud method and w e r e

f r o g g e d .

As

h a d been observed in other o l d structures,

the bricks

in the Eastview building w e r e in g e n e r a l laid 17frog down.

"

T h e white

bricks

u s e d as t r i m over wall openings

had

been

carefully chipped t o wedge-shape

in o r d e r to f o ~ m the arches ( s e e F i g u r e 2).

BEARING

SUPPORT

The b r i c k w o r k w a s supported on s t o n e masonry foundation

w a l l s , of

which

the n o r t h and w e s t were faced with

large

p i e c e s a£ carefully-

d i m e n s i o n e d s t o n e dressed to plane surface.

T h e floor beams separating the f i r s t a n d second storeys w e r e

supported on wooden strips (approximately 2

_by

_{4 inches in c r o s s - s e c t i o n )}

which were laid along a c o u r s e of bricks of the inner wythe. It appeared

the brickwork; these we,r e continued upward to f i l l the spaces between

the joists. A b o a r d was l a i d along the top of the wall, presumably nailed

t o the j o i s t s , and the rafters w e r e n o t c h e d t o f i t t h i s plate and w e r e apparently also nailed to the joists.

PERFORMANCE

The brickwork of the building appeared t o be in good condition,

and there was no indication of decay of the

bricks

or m o r t a r , or of cracking

or b u l g i n g of walls that might indicate s t r u c t u r a l weakness. T h e only

decay noticed

in

the building w a s rotting of s o m e of the floor beams w h e r e

they r e s t e d on the stone foundation. T h e s e w e r e heavy t i m b e r s , roughly

f i n i s h e d on the upper surface.

SUMMARY

An

old

building in Eastview, O n t a r i o , was found to have been built

of

brick

cavity w a l l s . T h e c o n s t r u c t i o n of two w a l l s was similar t o that

o b s e r v e d previously in

old

buildings, but the two other walls of the building

had

concealed bonding bricks, a type of construction

which

h a d not

previously been observed

in

t h e Division's studies, It i s believed that the bonding bricks were concealed in e r d e x to improve the appearance of the walls f a c i n g the s t r e e t ,

I t

_{is considered that}

_this

_{type of construction} p e r f o r m e d satisfactorily and d i d s o over a long p e r i o d of time.

F i g u r e 1 G e n e r a l view of the building shortly after the s t a x t of demolition (wall with 8 openings faces north).

Fi gur e 2 _{Pattern of bonding}

_bricks

_{of the} e a s t wall

(alternate header and stretcher bricks of

the bond course)

Figure 3 A concealed bonding brick of the west wall (outside wall surface on the left).