I just bought a house which was built in 2007 (Seattle area). The garage floor has no drain or expansion joints. As a result, there are some cracks in the concrete. They are small.

I was wondering if it is too late to add expansion joints. Ultimately, I'd like to finish the garage with epoxy coating. I wouldn't want to see new cracks showing up on the floor after I add the epoxy coating.

Thank you!

  • It's never too late to add expansion joints, but you might want to contact a local concrete guy first to make sure they are necessary.
    – Tester101
    Mar 31, 2015 at 19:46
  • I agree with tester about never being too late. The ones you have are not going to get smaller, so they will need repaired at some time. Nature wins every time, slabs crack. Expansion joints are really just an attempt to control where the cracks will be located. It makes some sense to wait until you are ready to epoxy the floor, before you cut expansion joints. Unless you are going to epoxy the floor on your own. If that is the case, when you have the pro come out to repaint it, you can have him cut the cracks at that point.
    – Some Guy
    Mar 31, 2015 at 23:09

1 Answer 1


You can cut expansion joints with something like this:

concrete saw

This is a walk-behind concrete saw that can be rented at most rental centers (I know that home depot has them).

After the joints are cut, fill them with a good polyurethane caulking.

I would wait until after you cut the joints before filling the existing cracks, as it's likely the work you're doing with the saw will result in vibration or "abuse" of the floor and might widen existing cracks.

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