How to Prevent Leaks in Cinder Blocks

Dig a trench around the foundation of your home, at the base of the cinder blocks. Use a shovel to dig the trench 36 inches deep and wide enough to insert a pipe 4 to 6 inches wide. Dig the trench on a downward slope so rainwater can drain down and away from the cinder block wall.

Clean the exterior wall of the cinder blocks by washing with a pressure washer. Allow the wall to dry completely and clear out any water that pools in the drainage trench.

Apply a waterproofing sealant to the outside of the cinder block wall. Spray or brush on the sealant according to product directions. Allow the sealant to dry, then apply a second coat for maximum protection.

Place a 4- to 6-inch-diameter plastic drainage pipe in the trench. Fill the area around the pipe with soil, then cover the pipe with 24 to 36 inches of gravel or until it is even with ground level.

Place a 4-inch layer of straw on top of the gravel to keep the gravel in place during heavy rains.

Clean the interior wall of the cinder block, using a damp sponge to wipe away dirt and grime. Allow to dry before proceeding.

Put on safety glasses and a dust mask or respirator. Apply a coat of interior waterproofing sealant to the cinder blocks. Allow the first coat to dry, then apply a second coat just as you did to the exterior.