Cracks in concrete blocks in your basement foundation don't have to be a mystery. The types of concrete block cracks can help you decode your foundation issues.
Concrete or cinder blocks are known as "concrete masonry units" (CMU) in the building industry. In a foundation wall, the blocks are joined together by mortar.
Concrete block cracks offer clues to a variety of foundation problems.
Finding a stair step or diagonal crack zig-zagging up your concrete block wall is an indication of soil pressure or settlement.
The crack also could be caused by soil movement resulting from the ground's freezing and thawing cycle.
Poor drainage or excess water can concentrate water in one location, damaging the foundation walls.
The cracking takes place along mortar joints between individual concrete blocks.
Large horizontal cracks are a serious threat. They could indicate a wall is in danger of bowing or collapse.
External pressure, including hydrostatic (water) pressure, could be forcing the walls inward.
A horizontal crack can also appear as a result of a one-time event, such as backfill damage.
Vertical cracks aren't as common as diagonal or horizontal cracks. Vertical cracks are an indicator of foundation issues, including drying shrinkage in the blocks.
The blocks may also shrink due to temperature-fluctuation shrinkage or carbonation shrinkage.
However, an external force, such as an impact on the wall, could also result in vertical cracks.
Identifying the type of crack your block wall foundation has is the first step. The next step is to contact the experts at My Foundation Repairs for solutions and close the case on the mystery of your concrete block cracks.