Turner Smith, Jr.
Q: We completed a 10-story building about 1 year ago. The building frame is concrete and the exterior is brick veneer. The exterior face brick recently cracked and disintegrated at the first floor window heads. The same thing is beginning to happen at the second and third floors. The problem is occurring only at corners and piers that are continuous the full height of the building. It looks like the brick is being crushed under its own weight. What is causing this and how do we fix it?
- A: The photograph does not show any horizontal soft joints. That is probably the problem: no horizontal soft joints were installed in the building. In the photo, the steel angle supporting the face brick is lying directly on the brickwork below. The joint at the toe of the shelf angle is pointed with mortar and tooled. No space is left for vertical movement of the brick.Without horizontal soft joints, the brick is forced to resist the shrinkage, creep, and elastic deformation the concrete frame undergoes as it ages. As the concrete shrinks, the load on the frame is transferred to the masonry. Eventually, the load exceeds the strength of the brick and the brick cracks. If adequate soft joints had been installed under the steel angles during construction, the angles would have continued to transfer the weight of the masonry to the concrete frame instead of to the masonry below.To solve the problem, replace the crushed brick and saw out 3/8-inch joints under the steel angles. Fill the cut joints with backer rods and caulking, not with mortar. Install these soft joints at every floor.In future buildings higher than three stories, be sure to install horizontal soft joints in brick veneer at each floor level. The shelf angle at each soft joint should not be continuous. Use 8- to 12-foot-long sections with a 1/4- to 1/2-inch gap between sections to allow for thermal movements of the angle. Also make sure the angles are properly anchored and shimmed so that they don't rotate and stress the masonry.