/ / / Waterproof foundation cracks by filling them in

Waterproof foundation cracks by filling them in

Let’s face it every house settles over time. And with that settling, the foundation can get cracks. Our house is no exception and the basement has cracks along the cinder block foundation. And we wanted to waterproof the foundation cracks. Here is one example of the cracks in our basement.

crack in cinder block foundation

A big problem with cracks in foundations is that water can now penetrate into the house. Which can be a really bad thing… So before we finish our basement we need to address any possible water problems. And the first step is filling in any cracks and holes in the foundation.

With this being a problem in a lot of houses, I want to share how easy it is to fill in a crack in foundations. PLEASE NOTE: Some cracks in a foundation can mean that you have a foundation problem that needs to be fixed by a pro.

OK, how about a list of supplies I used?

Waterproof Foundation Cracks

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  • hydraulic cement
  • H2O (water)
  • bucket
  • measuring cup (1/4″-1/2″ cup)
  • water spray bottle


Find the list of tools we use.

SIDE NOTE: Cool thing about this cement is that it can be used while water is leaking into a basement.

First thing I did was use the wire brush and brushed the area that needed fixing. This will remove dirt and particles from the foundation.

After I took the putty knife and ran it along the crack. I did this to widen and remove more loose foundation. The picture above is the foundation crack before and here it is after.

waterproof cracked cinder block foundation

fixing cracked cinder block foundation

TIP: A deeper/wider crack will help the cement!

Next, I took my shop-vac and vacuumed the whole area. Once I finished, I mixed my cement. I followed the instructions on the container. SIDE NOTE: This stuff will start drying within about 2 minutes of mixing. So make sure you only mix a small amount at a time.

hydraulic cement to fix foundation cracks

After mixing the cement, I took the spray bottle and sprayed some water into the cracks, only dampened the cracks (NO pools of water). The water will help the cement adhere to the foundation.

fixing cracks in foundation

I then took my trowel and applied the cement to the foundation. I made sure to apply pressure to the crack area to push the cement into the crack.

I continued doing this until all the cement was used or it was too hard to apply. TIP: Do not add more water to the cement!

Next, I remixed another batch of cement and followed the same process until all the cracks/holes were filled in the foundation.

waterproof cracks in basement walls

Something that you must do with cement is that it needs to remain damp (with water) for 24 hours. So every couple of hours I took the spray bottle and sprayed the area. By doing this, it will help the cement dry better and help prevent the cement from cracking as it dries.

After 24 hours my foundation cracks were all repaired, well the ones in this area at least. I did apply a coat of Drylock to the wall to help waterproof it even more. SIDE NOTE: I have now used Drylock and the Behr Masonary Waterproofer and I liked how the Drylock applied to the surface better.

If you are wondering how much this would cost, it would be about $20 and that is the cost of a trowel.

And that is how to waterproof a foundation by fixing the cracks in a foundation.

waterproof foundation cracks


  1. We just had to do this, but we went to the outside. We cleaned off with a wire brush and sealed with tar and a netting, applied Glace ice and water shield, tarred edges, and tarred again the next day and filled our hole back in. We no longer have water coming in!

    1. Hi Rachelle!!! I miss you girl! We did the tar on the outside in one place also. But we did not use the netting or water shield, I really like how you used that. If I ever have to do that again I am going to try that. Thanks for the tip!! Hope your doing well!

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