Sealing the Contemporary Wall Top
Protecting the top of masonry walls is an important design consideration when detailing masonry buildings. If water is allowed to penetrate the top of exterior walls, the entire wall system can be compromised, leading to efflorescence, deterioration, and eventually, its destruction.
Many types of masonry walls require proper capping, which can extend the life of the wall, minimize maintenance, and contribute to sustainability.
The components of a well-detailed and well-built top of wall are:
Wall caps are needed on exterior walls that end in a parapet above a roof (Figure 1). This detail might be used for an insulated masonry drainage wall ending just above a roof in which the vented air/drainage space is maintained. There are three important points to make. First, the stone coping cap has an overhang of about 1 ½ inches. Second, the coping cap is anchored in a mortar fill that is supported by a mesh restraint. And third, a continuous metal flashing extends the entire assemblage. Figure 2 shows the detail in three dimensions.
Wall caps also protect a simple site wall with an exposed veneer on two sides from potential moisture damage. Air and drainage space is essential in preventing efflorescence, keeping the wall dry and preventing deterioration. As with the vented air wall, it is important to keep a solid filled masonry unit or solid filled grout space beneath the stone cap for support and to provide a surface for a “full” mortar bed.
Richard Filloramo is Area Director of Market Development and Technical Services for the International Masonry Institute, New England Region's Connecticut office. With more than 35 years of experience, he has been involved with the design, construction, and inspection of more than 5000 building projects. He has created and presented several seminars on masonry.
You can find more information on these top of wall details on the International Masonry Institute's Web site, www.imiweb.org. IMI is updating and expanding its Masonry Detailing Series to include 2-D CAD details, 3-D animated details, actual jobsite and build photos, and a brief description and live video of the details being constructed. IMI also provides technical representatives to answer questions on these details at 800-464-0988.