Table 1 mathematically demonstrates how every brick masonry clad building will move. Fortunately, there are a few typical options to address the movement. In new construction, builders install vertical movement joints in the masonry every 6 to 7.6 m (20 to 25 ft), with additional movement joints at openings in the brick and corners. These joints are typically 8.9 mm to 12.7 mm (0.375 to 0.5 in.) wide and provide space for the brick to expand without affecting the adjacent component. Horizontal control joints are installed at the floor lines, typically every or every other floor line. Engineered movement joints may be applicable when dealing with dynamic movement due to wind or earthquakes. This article will not be exploring movement due to dynamic loading.
Maintenance, restoration, and replacement
Without the movement provisions mentioned in the previous section, the clay masonry can expand and damage itself or other building components. If an existing building has movement related damage, those movement provisions can often be installed as part of the solution. The extent of repairs is determined by the extent of the damage. Repairs can fall into three general categories: maintenance, restoration, and replacement.
Maintenance typically includes repointing of cracked mortar and replacement of a small, discrete number of bricks. If an older building only has mild damage, simple maintenance can be a viable solution. Most of the moisture-related growth has already happened, and the brick only experiences temperature-related movement; therefore, the maintained building will have to contend with less growth than it originally did.
Beyond simple maintenance, restoration may be required and could include future provisions for growth (i.e. control joints) and/or securement of the existing facade (e.g. post-installed masonry anchors). Control joints are an appealing option because they can be easily installed and will relieve the internal stresses in brick facades.
Masonry anchors, such as helical anchors, mechanically engaged anchors, or adhesive anchors, can mitigate future movement and secure problematic areas before they become unstable. Movement joints cannot typically be installed through an entire mass wall without changing the bearing condition and the lateral load resistance. Masonry anchors are typically better suited toward mass walls because veneer walls typically have a concealed water-resistive barrier (WRB) on the backup wall. Masonry anchors would need to puncture this barrier to anchor to the backup wall. This may be an acceptable risk if the cavity wall did not have a WRB to start with, or if the installer can demonstrate that an anchor passing through the WRB does not pose a significant risk.
