Fill the Gap Between a Concrete Patio and House

We’ve noticed water damage in our sunroom, which is bordered on one side by our concrete patio. After a quick investigation we believe that water has entered the gap between the patio and the foundation. If we’re right then that hopefully accounts for the water damage.

The gap in question was previously filled with either fiberboard or concrete crack sealant, but enough of it has deteriorated to conceivably allow moisture in.

To remedy this issue I installed backer rod in the gap that I then covered with concrete crack sealant. This will hopefully be the fix that keeps that wall of the sunroom nice and dry.

No Shortage of Gaps Permalink

You can see from the above photos all the small holes that had developed in the old concrete crack sealant. These hole occurred all along the length of the gap, which runs between two sides of patio and our house.

A Guilty Party Permalink

One reason for the porous nature of the gap can be attributed to old asphalt saturated fiberboard that had fallen apart. This affected most of the fiberboard between the patio and house.

Goodbye Deteriorating Fiberboard Permalink

I took a flathead screwdriver to the old fiberboard and ground away what remained of it.  I then vacuumed the debris to get the gap as clean as possible.

The Tools for Job Part I Permalink

Some of the tools that I used were closed cell backer rod, a spline roller, and a pair of scissors to cut the backer rod.

Install the Backer Rod Permalink

There’s not much to installing the backer rod. The goal is to push the backer rod to just below the surface and then apply the concrete crack sealant on top. In some cases areas the 3/4” backer rod was too thick, so I cut it up the middle with my scissors.

The Tools for Job Part II Permalink

I found the concrete crack sealant at my local big box store and applied it with my trusty caulk gun.

Apply the Sealant Permalink

Once the backer rod is in place the next step is to apply the concrete crack sealant. Note that there’s another variety that is self-leveling, which I decided wasn’t appropriate for my needs. My goal was to create a waterproof concave lip between the wall of the house and the patio and the self-leveling sealant obviously not designed for that.

Smooth Out the Coverage Permalink

I used a plastic spoon to guide the sealant into the nooks and crannies of the gap. I did my best to make it smooth, but it was difficult to do so given the surface.

The Next Day, Fully Cured Permalink

Time will tell whether this fix succeeds in keeping the moisture away from both the patio and house foundations.

I also hope that the color blends in better once the elements get to it.

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