This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
As walls usually carry greater loads than would be safely borne by the same area of the soil upon which they rest, they are spread out at their base by projecting the courses in off sets of a quarter of a brick until the desired width is obtained, as shown in Fig. 143. These projecting courses are called Footings, and it is usual to make the width of the lower course equal to twice the width of the wall above - that is to say, the number of courses on the footings is equal to the number of half-bricks in the thickness of the wall. All the external bricks of the footings should be laid as headers, so that they may tail well into the wall. The lowest course of footings rests upon a block of concrete, the width and depth of which is determined as explained in Chapter I.
Isometric view of Footings of on 18"wall.
22 1/2" wall.
Fig. 143. 27 Wall.
In walls of two or more bricks in thickness the lowest course of footings is generally laid double, while in very thick walls, particularly when they carry heavy loads, each course of footings should be double.
Instances of these double lower courses are given in Fig- 143.
Copings, or the topmost coverings of walls, are used for the purpose of preventing rain water from soaking down into the walls. They are very often formed of bricks laid on their edges across the wall, those of a highly vitrified nature being most suitable for the purpose. They afford greater protection if they project beyond the faces of the wall, thus throwing off the water, and for this purpose a " Creasing" - that is, a double course of slates or tiles laid to breakjoint - is sometimes used. A very good form of coping is one made of a highly vitrified clay, weathered on the upper surface and throated on the underneath to prevent water from running under them. All copings should be set in cement mortar, to minimise the chance of their being displaced. A few examples are shown in Fig. 144 - stone copings being left to be dealt with subsequently.