272. Brick piers are built in the same manner as brick walls. When they are less than 3 feet square, and support a beam, girder, arch, column, or lintel carrying a wall, the piers should, at intervals of not over 30 inches in height, have built into them bond stones not less than 4 inches thick, or cast-iron plates of sufficient strength and the full size of the piers. In height, isolated brick piers should not exceed 12 times their least square dimension.

The object of bonding a pier carrying a heavy weight is to distribute the load over the whole area, thereby causing the load to bear equally on each brick used in the construction.

The bond stones should be either granite, bluestone, or one of the durable limestones. The blue Vermont marble is also used, but the softer sandstones and freestones should be avoided.

Figs. 124 and 125 show the two types of bonded brick piers. Fig. 124 shows a pier bonded with 4-inch bond stones b, the stepped-off brick foundations at c, and the concrete base at d.

Brick Piers 126

Fig. 124.

Brick Piers 127

Fig. 125.

Fig. 125 shows a brick pier with 1-inch iron bonding plates at a, and the stepped-up brick foundation and concrete base at c and d.