All walls not covered by the roof should be capped by a wide stone called the coping. Horizontal copings should be weathered on top and have a drip at the bottom edge, as shown at C, Fig. 112. The width of the coping should be about 3 inches greater than that of the wall.
Gable copings do not require a weathering on top, but they should project about 1½ inches from the face of the wall, and should have a sharp outer edge, so that the water will not run in against the wall. As the weight of the coping has a tendency to cause it to slide on the wall, it should be well anchored to the wall, either by bonding some of the stones into the wall, or by long iron anchors. The bottom stone, sometimes called the "kneeler," should always be bonded well into the wall with a horizontal bed joint, as shown at K, Fig. 112. About once in every 6 feet in height a short piece of coping should be cut so as to bond into the wall as at Z. Gable copings sometimes have the part which rests on the wall cut in steps, so that each stone has a horizontal bearing. This method, however, is very expensive, unless the coping is cut in very short pieces, and this is objectionable on account of the number of joints required.
As a rule copings should be in as long stones as possible to avoid joints which admit the wet. Horizontal coping stones are often clamped together at their ends to prevent their getting out of place sideways.