Breeze blocks, also commonly called cement blocks, are traditionally used to construct building foundations and walls. The rectangular, rough finish blocks with open centres are generally preferred for their strength, versatility, light weight and affordability. However, like most wall building materials, breeze block walls can develop problems related to freezing weather cycles, extreme amounts of rainfall, pressure from nearby concrete structures and heavy vehicle traffic.
Although more common in the mortar than in the breeze blocks themselves, cracks are normally caused by shifts in the concrete footing on which the wall is built, pressure from underground water or saturated soil, or heavy vehicles or equipment that cause extreme vibrations in the structure when operated nearby. A vertical crack that is fairly consistent in width and has a wall on one side that is taller than the other is usually due to an unstable footing. If the crack is erratically shaped, the footing was likely installed over bedrock, a boulder or poorly compacted fill that make the wall sag on one or both sides.
If a breeze block wall is leaning or tipping to one side, the aforementioned circumstances that cause cracks are probably the root of the problem. In areas that experience extremely cold temperatures, repeated heavy frosts can break down the concrete footings and make the wall lean.
Buckling and Bulging
Breeze block walls that develop bulges and buckles in various spots are commonly part of a basement or cellar that has another structure atop it that is too heavy for the wall to bear. The bending of the wall may also be caused by the weight of earth or accumulated water above it.
If breeze block walls appear to be horizontally sliding over top of lower wall portions, the problem is often attributed to the lack of vertical steel reinforcements in the structure. This is called shear failure. The protruding blocks may be at the top of the wall or further down and are most common in walls that are solely secured by an underlying concrete slab.
Once a breeze block wall has exhibited physical abnormalities, it is usually beyond repair. Although exterior steel reinforcements may delay further deterioration, the wall will eventually fail and have to be replaced, a difficult and costly task that requires jacking up or securing the surrounding ceilings and walls. To prevent future breeze block wall failure, building contractors usually recommend using vertical steel reinforcements in the construction and contracting the job with a licensed masonry professional.