The board recently engaged Brown & Beattie to review cracks which were evident on some of the end units at the complex. During their inspection of the townhouses, they noted evidence of cracking along the mortar joints between the bricks and some cracks in the foundation (see pictures below).
According to Brown & Beattie, the noted pattern of the cracking appeared to be related to seasonal expansion and contraction of masonry veneer (due to thermal and moisture changes in the brick), potentially in combination with shrinkage cracks in the concrete foundation walls that occur as the concrete cures after initial placement.
Shrinkage cracks may have created initial internal stresses in the mortar joints above, initiating some of the noted step cracking. The cracking appears to be most prominently located at the long “narrow” brick panels between the window penetrations or at the “steps” in the foundation walls.
At these narrow panels of masonry, cracks can form along the “shortest” part of the panel as it is the “path of least resistance” to accommodate the differential movement (i.e. between window penetration). Similarly, cracks related to season expansion and contraction can occur in areas where the geometry of the brick panels change given differential movement between the different panel lengths, such as at the “stepped” portions of the foundation walls which have longer masonry panels above. The longer masonry panels will typically want to expand and contract more than the shorter panels below the “step”.
Brown & Beattie do not believe the noted cracks are of immediate structural concern. They believe the previous tuck pointing repairs likely failed as the rigid mortar was unable to accommodate the expansion and contraction movements in the masonry.
After reviewing these findings with Brown & Beattie, the board engaged them to create a spec and go out to tender. This spec outlined that the cracks be routed and repaired with a flexible repair material (such as sealant) and be monitored accordingly. The scope of work also includes provisions to install vertical control/expansion joints within the concrete brick masonry in order to accommodate noted expansion and contraction joint movement.
Additional crack gauges would be installed to monitor the extent of movement/crack widths over regular seasonal changes
August Restoration were selected from a bid list of five contractors. The work is scheduled to start May 13th, with a conclusion date of June 10, 2024.