Copyright Goodheart-Willcox Co., Inc. 308 Section 4 Construction Details is important that the degree of curvature be suffi- cient. The radius of curvature of a 4″ wall should be no more than twice the height of the wall above the grade. The depth of curvature should be no less than 1/2 of the height. Figure 14-68 shows the details of a typical serpentine wall. Caps and Copings Caps and copings channel water away from a building. A cap is a covering within the height of the wall, normally where there is a change in wall thick- ness. A coping is the covering at the top of a wall. The cap and coping may be a single unit or multiple units. The tops can slope in one direction or both directions. Where caps are discontinuous, a minimum slope from the ends of 1/8″ per 12″ should be provided. Caps and copings may be made of brick, precast or cast-in-place concrete, stone, metal, or terra cotta. See Figure 14-69 and Figure 14-70. Because caps and copings are exposed to extreme weather conditions, brick masonry may not be the preferred choice because it requires more joints than other materials. Goodheart-Willcox Publisher Figure 14-68. Details of a serpentine garden wall showing the plan layout and wall sections. 21' 6" length Depth 48" 4" 8' radius0" 8' 0" radius 4" 4' 8" height Varies Section Grade Elevation Grade Plan Brick Industry Association Figure 14-69. Stone or precast concrete coping for parapet wall. Dovetail slot 1" (25 mm) min. Dovetail ties Precast concrete or stone coping Sealant and backing rod Flashing Metal ties Airspace Dovetail ties Reinforcement, both horizontal and vertical Solidly filled with grout Flashing and counter-flashing Rigid insulation