The local ordinances in some municipalities require thicker walls
with hollow tile construction than where common brick backing is
used, which affects the comparative cost of the buildings; but,
where the total thickness may be kept the same as for solid brick,
the cost is practically the same, with slight differences one way
or the other in different communities. The tile used for backing
may be either soft or hard burned, but never with an absorption
of over 12 per cent, and are scored variously so that there may
always be a good keying surface for plaster. These tile may be set
with the hollow spaces or cells running either horizontally or
vertically, as the case demands or the builder chooses.
[Sidenote: Construction]
Walls of this form of construction are built in much the same
manner as walls with common brick backing, except that it is always
desirable to use cement mortar with the tile to insure the needed
strength of bond. The face brick are first carried up four or five
courses and then the hollow tile units, of whatever thickness
chosen, are laid up behind the brick, leaving an inch space between
the tile and brick (Fig. 31). The tile are laid, with broken joint
as in running bond, in a half-inch mortar bed. When the tile width
is over 4 inches, the mortar should be spread only on the front and
back edges of the tile, leaving a hollow space in the center. In
the vertical joints only the front and back webs require mortar. If
vertical tile are used all the webs should be well mortared, while
the vertical joints are simply buttered.
Care must be taken that the space between the tile and brick does
not get filled up with mortar, for this would defeat its purpose
of serving as an insulation against moisture and cold. With this
one-inch space between brick and tile open, furring and lathing
are saved, as the plaster may be directly laid on the tile and the
necessity of fire stops avoided.
[Illustration: Fig. 31. Face Brick on Hollow Tile]
At window and door openings, in case 4" × 5" × 12" or 8" × 5" × 12"
horizontal tile are laid, either common brick or special half and
full closure tile (Figs. 31 and 59) should be used, in order to
close the openings at the end of the horizontal tile courses, thus
making around the frames good joints which should be tightly filled
with mortar. When the 12" × 12" tile are laid horizontal, those in
the window and door jambs need simply be set vertical to serve as
closures.
It will be found that an even number of tile does not always work
out with the length of the wall or pier, leaving a space of a few
inches. This space may be filled by cutting a tile or using pieces
of tile slabs.
[Sidenote: Tile Sizes]
For houses of the character presented in this Manual, tile either
4, 6, or 8 inches wide may be used, depending on local ordinance
or the choice of the owner. A 5-inch backing may be obtained by
simply laying the 4" × 5" × 12" tile on the 5-inch edge. Both 4-
and 8-inch widths are made 5" × 12" or 12" × 12" in height and
length. The 6-inch width generally comes 12" × 12" in height and
length, but may be obtained in the 5" × 12" size from certain
manufacturers, if so desired.
The 5" × 12" tile in either width are laid horizontal, while the
12" × 12" tile in either width may be laid vertical or horizontal.
Either method is satisfactory although, for heavy bearing walls,
some builders prefer the vertical method on the ground that it
gives a stronger bearing wall because the vertical webs directly
bear on each other. If laid vertical, the top course of tile should
be placed horizontal to give a good bed for the wall plate.
[Sidenote: Face Brick to Tile]
Four courses of standard size brick, provided a 3/8-inch mortar
joint is used, will equal in height two 5" × 12" tile, making every
fifth course a bonding course (Fig. 31). And five courses of
standard size brick, provided a 1/4-inch mortar joint is used, will
equal in height one 12" × 12" tile, or if 1/2-inch joints are used,
will equal in height 3 courses of 4" × 12" tile 5 inches wide,
making every sixth course a bonding course. If wider mortar joints
are desired, you can in the latter case make every fifth course a
bonding course by using 12" × 12" vertical tile which you can order
cut to any length required. But where either the 5" × 12" or the
12" × 12" tile are laid horizontal, the number of courses of face
brick and the size of mortar joints cannot be changed.
[Sidenote: Bonding]
The face brick are bonded to the tile backing (Fig. 31) precisely
in the same manner as previously explained for common brick, double
headers being used in case of Stretcher Bond and the headers,
wherever required, in other bonds (See page 18). But as this wall
is full 9 inches or more thick, the headers in the bonding courses
leave recesses one inch or more deep at intervals on the inside
face of the wall (Fig. 31). These if shallow, should be filled with
plaster, containing a large amount of fibre, before the regular
plastering is started; if deep, as when the 8-inch wide tile is
used for backing, a stretcher course of common brick or brick-size
hollow tile fills the space.
The chimney construction does not differ in any essential from
that used for the solid brick wall, but we strongly urge the use
of brick for the chimney, rather than tile or concrete blocks, as
affording more reliable protection for the flue.
The window sills, door sills, and lintels are the same as in solid
brick construction except that, preferably, instead of the wooden
lintel supporting the backing, the lintel be made of hollow tile
filled with cement and reinforced by one or more steel rods (Fig.
32). These tile lintels should be made on the ground by standing
the tile on end for filling. When the concrete is set, they are
ready to be lifted into place.
[Illustration: Hollow Tile and Steel Lintels]
[Sidenote: Laying Out]
The story heights should be figured so that an exact number of
whole tile may be used from the bottom of the joists on one floor
to the bottom of those on the next floor, always allowing one-half
inch for the bed joints. But where this is not possible, special
tile slabs one inch thick, which may be had from the dealer, should
be used to obtain the exact height required, so that an even and
solid bearing may be formed for the floor joists. The wall plates
for the roof construction are anchored in the same manner as in the
solid brick wall, except that anchors should be 20 inches long;
likewise, brick nogging should be placed between the roof rafters.
As in the case of the solid brick construction, when the plasterers
have gone, the face brick should be cleaned down and pointed where
necessary.