How to Patch Leaky Basement Cracks

Check the Grade and Use Hydraulic cement

By Mark J. Donovan

The first step in patching a leaky basement crack is to solve the water runoff problem on the outside of the home. On the outside of the home make sure there is a sufficient grade away from the home. If there is no grade, or a negative grade (surrounding land flows toward the home), then fix this problem first.

Second make sure your gutters are clean and that water draining from the drain spouts flows away from the home.

Once you have confirmed that water is draining away from the home you can now begin to patch leaky basement cracks.

Hydraulic cement is great for patching a leaky basement crack. Before applying the hydraulic cement open the crack up with a hammer and chisel. When making the crack, undercut the crack so that the inside opening of the crack is wider than the surface opening. This will help the hydraulic cement to lock into the crack as it hardens.

After opening up the crack, clean the crack well using a rag, broom and/or brush.

Next mix up some hydraulic cement per the instructions listed on the packaging.

When applying the hydraulic cement you should do it in a two step process. First dampen the basemen crack a little and then apply a base layer of hydraulic cement such that it sits about ½” below the base of the crack surface.

Once the base layer has dried, apply another layer of hydraulic cement to the crack and smooth it to match the surface layer of the basement floor.

After the hydraulic cement has dried it is a good idea to apply a waterproofing sealer to the entire basement floor.

For more help on Basement Additions, see’s Basement Remodeling Bid sheet. The Basement Remodeling Bid Sheet will help ensure that your hire the right contractor so that your basement remodeling project is done correctly and you get the project finished on time and budget.

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