[Sidenote: Thickness of the Wall]
Where ordinances do not govern, the thickness of brick walls
above the foundation may be 8 inches (two brick thick) for one or
two-story small houses, except in the case of an unusually high
gable where the first story wall should be 12 inches (three brick
thick).
[Sidenote: Water Table]
At the grade line the face brick is started, sometimes with a
rowlock course or a soldier course, set either flush with the outer
surface of the foundation wall or, as usual, slightly projected,
in which case it is known as the water table. On the other hand,
the entire base or lower portion of the building from the grade to
the first floor sometimes extends as a water table beyond the wall
above. Figs. 2-7 show various ways of treating this portion of the
wall which add to the interest of the brickwork.
The method of laying the face brick is substantially the same as
that for the foundation wall except that much greater care must be
taken with the bond and mortar joints on the surface of the wall.
A description of various bonds and patterns will be found on pages
33-35.
[Sidenote: Building]
The method of bonding the face brick to the common brick backing
follows the usual method Bonding means of headers every five or
six courses, the headers in other than Common Bond, not used for
bond, being cut in half. In the widely used Stretcher Bond where
no headers occur except at corners, three methods of bonding may
be employed. First, but only in case of walls 12 inches or more
thick, the back corners of the face brick may be clipped so that
the backing brick fit diagonally into the notches thus provided
(Fig. 8). This sort of concealed bond is weak and should be avoided.
[Illustration: Fig. 8. Concealed Bond]
[Illustration: Fig. 9. Metal Wall Ties]
Secondly, the face brick may be tied to the backing by laying
metal strips or wires, supplied by any material dealer, in the bed
joints of face and backing brick (Fig. 9). Although this method is
frequently used and in a way answers the purpose, we do not regard
it as the simplest and best.
We recommend the third method which is a natural bond, thoroughly
workmanlike and sound. Every sixth or seventh course, pairs of
headers are laid with a tight buttered, and hence invisible, joint
alternating with the stretchers. As the joint between the headers
is hardly seen, the two headers give the appearance of a stretcher,
so that the effect of the Running or Stretcher Bond is maintained
(See Fig. 31).
[Sidenote: Backing]
The face brick are laid up five or six courses in advance of the
backing and the joints on the face of the wall are finished (See
Fig. 57) as the work progresses. On outside exposed surfaces, the
struck joint should be avoided, and particular care should be
taken in seeing that all head or vertical joints are thoroughly
filled with mortar from bottom to top. Each face course should be
started so as to care for the bond or pattern chosen, as well as
for the transverse structural bond. The backing is then laid in
the usual way, always, so far as possible, breaking joint with
the face brick. No attempt, except where strength is specially
demanded, should be made to slush the thin space between the front
and back tiers of brick, as this space helps to make the wall drier
and warmer. Wherever the common brick backing is to be exposed,
the joints must be neatly struck as in the basement wall. At the
close of the day's work, face and backing should be brought to
approximately the same level and covered to protect the work from
the weather.
[Sidenote: Treatment of Joints]
The brickwork should be stopped at the point where the first floor
joists are to rest upon it, and care should be taken to have the
top course perfectly level, so that the joists may be set without
wedging or blocking. The joists set by the carpenter should have,
at intervals of approximately six feet, wrought iron joist anchors
solidly spiked to them, and extending into the wall. Great care
should be exercised in placing these anchors as near the bottom of
the joists as possible in order to lessen the strain on the brick
wall, in case a fire causes the joists to drop.
[Illustration: Fig. 10. Correct Joist Anchor]
[Illustration: Fig. 11. Bad Joist Anchor]
For the same reason, the ends of all the joists, with or without
anchors, should be beveled so that, in like conditions, the
joists will readily fall out without injury to the wall. Fig. 10
illustrates the correct method of attaching the anchor to the
joist. The dotted lines show how the joist would drop without
damaging the wall. Fig. 11 shows the destructive effect caused by
the anchor being placed at the top of the joist. The importance of
these points cannot be emphasized too much as walls have had to
be rebuilt which by proper framing construction would have stood
intact. After the joists are placed, the brickwork is continued up
between, and leaving a small "breathing" space around, them. The
same method of joisting is followed at the upper floors.
[Illustration: Fig. 12. and Fig. 13. True Corbeling Between Joists]
If the lower part of a wall is thicker by a brick than the upper
part, it should be carried up its full thickness nearly to the
top of the joists Fire Stops where ft is stepped back to the
inside face of the upper part, thus forming with the plastering
a fire stop at the top of the joists, while a projection of a
quarter brick length should always be provided as a fire stop at
the bottom of the joists, as shown in Fig. 12. If the wall is the
same thickness throughout, the brickwork should be corbeled out
between the joists two inches, the full height of the joists,
to form a fire stop as in Fig. 13. The object of the fire stop
is to block all possible passage of fire from the space between
the joists to that between the furring strips on the wall, or
the reverse. Without these fire stops, a fire originating in the
floor could communicate with the furring space on the wall above,
or originating in the furring space could communicate with the
floor. With the stops, the fire is confined to certain spaces and
is retarded instead of spreading. These corbels also serve the
wholesome purpose of checking vermin of all kinds from passage
through the floor and wall spaces.
[Sidenote: Ceiling Lath]
Figs. 12 and 13 also show the proper way of placing the lath at
the corner of the ceiling so as to take full advantage of the fire
stops. The ceiling lath, usually placed first, should be started
far enough away from the side walls so that when the side wall
lath is placed tight, as it ought to be, against the underside
of the floor joist, there will be space enough for the plaster
to push through and form a key touching the bottom brick of the
corbel. As the corbel by construction is necessarily the distance
of a mortar joint above the bottom of the joists, the openings are
thus completely sealed by the plaster key. In cheap speculative
buildings, these fire stops are too often omitted or a pretext for
them is resorted to by projecting only one brick at the top or
bottom of the joists. This, however, is as good as no fire stop at
all. Figs. 14 and 15 show the lath as they ought not to be placed
and also how false corbeling leaves the passages really unstopped,
thus defeating altogether the purpose of fire stops.
[Illustration: Fig. 14 Fig. 15