In addition to the above criteria, renovators cut new control joints to separate the masonry piers from the masonry above the window openings. They provided a new mortar joint to re-support the masonry assembly above the window openings, where the masonry had lifted. Additional restoration anchors, rust inhibiting paint, and new through wall flashings were also installed.
In retrospect, two design features in the original construction could have prevented this situation.
- The relieving angles should not have extended into the adjacent piers.
- Vertical control joints should have been installed between the masonry piers and the masonry above window openings.
Case study 3: Growing, growing, gone
Part 1
A university building was constructed in the late 1960s with brick cavity walls and tall, multistory, industrial windows. The windows end beneath the top floor, creating a brick band that spans the entire 48.8 m (160 ft) elevation. No control joints were installed in this brick band at the time when the building was being constructed
Expandable foam and sealant joints were installed at the corners, possibly as an afterthought attempt to provide movement capability. In any case, the foam and sealant at the corner allowed the brick to expand freely past the adjacent corner brick. The 45.7 m (150 ft) length of brick expanded without restraint, and the brick moved almost a full inch past its corners.
While this brick expansion did not damage the adjacent corner brick, it did impact the brick anchors. During the investigation, the brick anchors on the extents of the 48.8 m (160 ft) brick band were found to be bent at almost a 45-degree angle. While the brick anchors were still engaged, they were being stressed to their limits along with typical wear and corrosion for a component of such an age.
Since the brick ties were bent and overstressed, the lateral stability of the brick assembly was deemed insufficient. Installing new helical masonry anchors through the face of the existing brick assembly into the wall’s substrate was considered, but this would compromise the existing WRB behind the face brick. This left a full-on replacement as the only remaining option. Removing the brick allows an opportunity to install new brick anchors, repair/replace the existing membrane, and install new brick with control joints properly spaced out.
Part 2
At an adjacent building on the university’s campus, a bump out addition was constructed in the late 1970s. Adjacent to the existing building, the addition’s facade was a 9-m (30-ft)-wide white brick cavity wall with no openings or control joints. At the edge of this wall, the brick wall turned 90 degrees for a short, 0.6 m (2 ft) return near the existing building.
A large vertical crack developed on the facade wall near the corner, and the small return section rotated away from the rest of the wall. The expansion of the 9 m (30 ft) wall had pushed towards the corner, which was resisted by the perpendicular brick creating stress. This stress was only relieved when the brick cracked vertically, effectively separating the corner from the rest of the wall.
