Clay bricks are as small as they are ever going to be the day they come out of the kiln. Concrete is placed wet and air cured. Over time, the concrete shrinks, while the bricks swell from exposure to water. Cast-in-place concrete and wood framed construction clad in brick masonry cavity walls must allow for the different movement of these components.
In the masonry cavity wall example shown, floor line relieving angles were not installed in sufficient frequency and the angles that were installed did not adequately allow for the differential movement. The windows are attached to the CMU infill on the concrete superstructure and have a nosing that bridges onto the clad side of the wall. The brick swelling/concrete shrinking dynamic has opened the sealant joints at the head and portions of the sill, while shearing the sealant at the jambs.
Considering the age of the building, the average amount of annual movement per brick is about 0.0002". The actual movement is on a curve, the additional differential will be less extreme than the initial swell/shrinkage scenario.
A more robust sealant profile and material can be used that will accommodate more movement than the original sealant. Other concerns may be more pertinent, such as evaluating the degree of damage that has resulted to the window frames as a result of the movement.
The video shows a schematic of the movement and examples from the case study. The case study illustrates the need for the building envelope inspector to give consideration to long term building movement in the analysis of the water management performance of installed systems.
