Q. I am working on a house with a leaky walk-out basement. The house is surrounded by a sidewalk on the three sides above the walkout, and water seems to be seeping through the control joints in the sidewalk into the basement. How can the joints be sealed to stop the leaks?

A.A pour-in, rubberized crack-filler can be used to seal the joints, but the joints may not be the problem. Often the backfill has settled under a sidewalk or patio slab, creating a void near the foundation. Water can then run into and along this void from any entry point. There may be a downspout or other source that is directing surface water into this void, or it could be soaking through the soil from outside the walks. The void can be filled with concrete using mud-jacking equipment. Mud-jacking can also tip the sidewalk away from the foundation slightly, in case it has settled toward the house.

If the basement wall is concrete block, water can enter almost anywhere and flow through the cores to a leaky area of the wall. In this case, first eliminate the surface water. If this does not solve the problem and you can’t locate and stop the water source, you may have to remove the sidewalk, excavate around the foundation, and apply a waterproofing membrane and adequate perimeter drainage.