The tops of masonry walls are often the most vulnerable to moisture infiltration, and special care must be taken to design and install a proper wall cap. Wall caps and flashing directly beneath the cap must be impervious to moisture penetration.
Wall Cap Types
Types of parapet caps include stone, cast stone, clay brick masonry, concrete masonry, and formed sheet metal. Parapet caps should slope in towards the roof. All parapet caps (except for sheet metal coping) should incorporate through-wall flashing directly beneath the cap to prevent moisture from saturating the wall beneath. Joints between wall cap elements are often finished with a flexible sealant.
Most situations require stone or masonry wall caps to be anchored to the wall below. Without anchors, wall caps will loosen as the wall below responds to temperature and moisture variations. Anchors are also required to satisfy prescriptive requirements for seismic design, which state that: “component seismic attachments shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity” (ASCE (American Society of Civil Engineers) 7-05, Section 18.104.22.168). Anchors may be installed into blind holes in the bottom of coping segments or in mortar joints between units.