Filling Gaps: Concrete Slab & Wall

Have you noticed a gap between a wall in your home and a concrete slab? If so, you may be wondering how you can go about filling it out. Read on for a step-by-step guide on how you can fill gaps between a concrete slab.

Measure the Size of the Gap

The first thing you need to do is measure exactly how big or small the gap is. This can easily be done with a measuring tape or ruler. Anything below 1/4” inch can be filled up directly with caulk. If the gap is larger than that, you will need to insert a backer rod before filling the gap with caulk. Once you have completed this step, you can smooth out the caulk.

It’s a good idea to measure the gap at a few different points, as some sections may be wider than others. In this case, a backer rod will also be required.

Get the Tools and Materials You Need

Now they have an idea of how to go about filling up the gap, it’s time to get the tools and materials you need. This will include the caulk of your choice — we recommend urethane caulk for this purpose. You will not want to use silicone caulk to fill up a concrete slab.

Some other items you will need include:

  • A caulking gun
  • A backed rod (if applicable)
  • A spoon or caulking tool
  • Disposable gloves
  • Mineral spirits

Insert the Backer Rod

If a backer rod is necessary, the first thing you will need to do is insert it into the gap. But before doing that, make sure to measure the length of the gap and cut the rod to correspond with it. Then, press the rod firmly into the gap. It should be at least ¼” below the surface.

Start Caulking

Now that the backer rod is in, it’s time to start the process of caulking. Remember to put on a pair of disposable gloves before starting work. Work the caulk tube into the caulking gun and start filling up the gap, making sure that it is completely covered.

Take the Opportunity to Caulk Small Cracks

After you have filled up the main gap in between concrete slabs, take the opportunity to fill out any surrounding small cracks. Before doing so, always make sure that these cracks are thoroughly clean and dry. This is a preventative measure that willprevent the small cracks from widening into larger gaps in the future.

Smooth the Caulk

Once you are satisfied that the caulk is in place, it’s time to smooth it for a neater and more uniform appearance. You can do this by dipping a spoon into mineral spirits and using the back of the spoon to even out the caulk.

Finish Up

Now, on to the last step. When cleaning up after the job, you can use mineral spirits to get the caulk off any tools you have used. Urethane caulk can be stubborn and hard to remove, which is why you want to use mineral spirits.