Footings.1 - The general question of footings for walls will be considered in the chapter on Foundations, Part II. It will be sufficient now to place before the student the figures 108 to 112 giving sections of footings for brick walls from 1 to 3 bricks in thickness.
Fig. 108. Footings, 9-inch wall.
Fig. 109. Footings, 14-inch wall.
Fig. 110. Footings, 18-inch wall.
1 Sc. Scarcements.
Fig. 111. Footings, 1' 10 1/2"-wall.
Fig. 112. Footings, 2' 3"-wall.
For example, the plan of the lowest course in the footings of Fig. 110 is the same as that of the lowest course in the wall three bricks thick, shown in Fig. 112.
The footings of buildings generally rest upon concrete, which is not shown in the figures (see Part IV.)
A good bed of concrete will effectually distribute the weight of a wall over the ground upon which it is built, and the gradually projecting courses of footings may, when bye-laws do not prevent it, often to a great extent, or in some cases entirely, be omitted.1
Quoins in brickwork can hardly be made stronger than the rest of the walling: they should, however, be built with great care, and are often constructed in gauged work, divided for appearance into blocks, which may be made to project slightly from the face of the wall. Stone quoins are often used with brick walls.
Glazed pottery, vitrified brick, fire-clay, concrete blocks, and 1 The rule for footings in the Building Act is as follows: - "The projection of the bottom of the footing of every wall on each side of the wall, shall be at least equal to one-half of the thickness of the wall at its base; and the diminution of the footing of every wall shall be formed in regular offsetts, and the height from the bottom of such footing and the base of the wall, shall be at the least equal to one-half of the thickness of the wall at its base." terra-cotta copings may also be used with advantage, for the same reasons.
The hardest and least porous bricks should be selected for copings, and should be set or pointed in cement.
Fig. 113 is a section of the common "brick-on-edge" coping. A double course of tiles or slates, in either case called "creasing" is sometimes substituted for the projecting course of bricks, marked A.
Fig. 113. Brick-on-edge Coping.
Fig. 114. Brick Coping.
Fig. 114 shows a brick coping of a more ornamental character.
Brick or clay-ware copings made in complete sections, such as those in Figs. 115 and 116, are far preferable to those built up of ordinary bricks, as they are generally of more impervious material, have fewer joints, and can be throated like the stone coping in Figs. 129, 131.
Cornices (see p. 8) may be introduced in brickwork with great effect by "corbelling" out the bricks without cutting them, and also by placing projecting bricks with their angles to the front of the wall, technically known as "dogs'-teeth." A simple brick cornice is produced by allowing every alternate header to project from the face 1/4 or 1/2 a brick.1 Above and below these headers are courses of stretchers, projecting and receding 1/4 brick respectively. Such a cornice is shown in Fig. 117, the moulded member on the top being a cast-iron eaves gutter.
Fig. 117. Brick Cornice with Gutter.
Fig. 118. Brick Cornice with Gutter.
Fig. 118 gives an elevation and section of a more elaborate brick cornice.
1 Quarter-brick projections are generally bald and unsatisfactory in appearance.
Eaves Courses are formed by projecting bricks in a similar manner.
Fig. 119 is the section of a wall corbelled out to carry a wall plate. In brickwork the projections of the courses should never be more than 1/4 brick (2 1/4 inches), in order that each back joint may be kept well within the last course. When great strength is required, the courses may project only 1 1/8 inch or 1/8 brick.
Stone corbels are often used in brickwork (see Fig. 287).
String Courses in brick walls are frequently of clay-ware or stone, but are sometimes formed with the bricks themselves, by projecting two or three courses from the face of the wall. The upper surface of the projecting portion of a string course should be weathered or splayed to throw off the wet.
Sometimes a fillet of cement is used to effect this.
Fig. 119. Corbel in Brickwork.