Foundation Crack Repair

How to repair foundation cracks
just like I do

Foundation crack repair isn't just for the pro's anymore. If you're a homeowner with cracks in your basement walls or a commercial building owner with cracked concrete walls, there's a way to repair these cracks yourself. 

If you've never repaired a cracked foundation wall before, it may seem a little intimidating, but after reading through this page and watching the video, I think you'll be able to do it just fine. 

My company, Day's Concrete Floors, Inc was asked to repair 75 cracks in the concrete walls of a large warehouse. These cracks were all less than 1/4 inch wide and went from the top of the foundation wall to the concrete floor.

Most of the cracks leaked water when it rained out which lead to the floor getting very wet. The owners needed the cracks fixed and the foundation water tight.

This is the warehouse above.  The cracks in the foundation were all the way around the perimeter of this 500' x 150' building

Here's a look at one of the cracks in this foundation. Most of them were like this, some were not so wide. As you can see, like most of them, this crack is leaking water from the outside.

Here's a couple more cracks above. Some cracks were leaking from the middle of the foundation, some from just the bottom, and some from the top.

The plastic "tabs" you see in the picture are the injection ports we have already installed in preparation for fixing and waterproofing the crack.

The foundation crack repair kit I use is from RadonSeal. They've got an easy to use DIY crack repair kit that includes everything you need to fix cracks like the one's above. 

Installing the injection ports

The first thing we did was clean the cracks with a wire brush. The wire brush will remove any loose concrete, dirt, and dust. Then we mixed up some of the epoxy surface sealer to install the injection ports like you saw in the pictures above.

The epoxy comes out of the tube in 2 parts, one is black and one is white. When you have both parts mixed correctly, the epoxy will turn grey.

Just put a little on the back of the port and stick it over the crack. Do this about every 8 inches from the bottom of the crack to the top.

Once all the tabs are in place, the crack needs to be sealed on the surface using the epoxy surface sealer. Using the included putty knife, smear enough epoxy over the crack and the tabs to completely seal the crack.

The foundation crack repair material that gets injected into the ports is very fluid and will leak out of any holes that aren't sealed up.

Sealing the surface of the crack

Sealing the crack with the epoxy sealant is quite easy. An 8 foot crack took us about 2 minutes to seal after the ports were in place.

This is what a foundation crack will look like after you have installed all the injection ports and sealed the surface of the crack with the epoxy.

It takes between 2 and 4 hours for the epoxy to dry before you can inject the crack with the repair material.

Injecting the crack with polyurethane

This kit has a 2 component polyurethane foam we injected into the cracks to repair and seal them.

We use this material because it expands up to 20 times its volume, filling up the entire depth of the crack with hydrophobic foam that repels water and will not break down over time.

Once the polyurethane has cured, the foundation crack will never leak again because water can't penetrate it from the back side.

Don't buy the cheaper single component foam kits. This foam breaks down over time and the crack will leak again.

Start injecting the crack from the bottom. Once you see fluid coming out of the next port, remove the hose, plug the port with the plug cap and insert the hose in the next port.

It could take anywhere from a few seconds to a couple minutes for the liquid foam to get to the next port. It all depends on the size of the crack.

Most of the time it took me under a minute. Most of the cracks took me about 5 to 15 minutes to fully inject. The really narrow hairline cracks took the longest because I had to really take my time squeezing the polyurethane into the crack.

The foundation crack repair after it's sealed

This is what the foundation crack will look like when the polyurethane foam is dry.

You can see the foam after it has expanded. Some of it came out of the top of the crack and some of it found some pin holes we either didn't get sealed up or couldn't see because they were so small.

This foundation crack was completely repaired and water tight after using the repair kit from RadonSeal.

All 75 cracks we injected were water tight after being repaired.

Below are a couple other cracks showing the foam after it has expanded. Most of the time the excess foam comes from the top of the wall where the crack isn't sealed

The picture below really tells the story of how well this foundation crack repair material works. This picture is of the back side of one of the cracks.

The 2 component urethane foam has completely expanded to seal the entire crack from top to bottom. Water and no longer penetrate this crack.

We had great success using RadonSeal's 2 component polyurethane foundation crack repair kits on this job. I highly recommend using their repair kit for your foundation cracks.

RadonSeal has a PRO kit for contractors like me who do these repairs a lot and they have a DIY kit for the homeowner who only has 1 or 2 foundation cracks to repair.

The kits come with easy to follow instructions as well as a CD to watch and show you how to do this.

Below is an instructional video from RadonSeal showing the process from start to finish.


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