Face Brick on Hollow Tile Construction
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.
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.
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.
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.
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.
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.
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.