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Community and Q&A

Concrete floor caulking is failing… why and how to fix?

Steve Hengeveld | Posted in Green Products and Materials on

My polished concrete floors are about a year old. Now I see that the caulking the contractor laid in the seams is starting to crack and split (see photo). The splitting appears to be occurring more often in the part of the floor that gets sunshine.

Anyone know why this is failing so soon? Was the wrong material and/or technique used? What is the fix? Thanks.

Port Townsend WA

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  1. Steve Hengeveld | | #1

    I forgot to add; the seam in the photo is about 3/16ths inch across.

  2. John Clark | | #2

    I've read that it can take about a year for fresh concrete to shrink into its permenant size.

  3. GBA Editor
    Martin Holladay | | #3

    It's hard to judge at a distance. There are lots of possibilities: for example, the contractor may have used the wrong product, or may have used cheap caulk; the contractor may not have used a backer rod.

    You didn't tell us whether the slab is indoors or outdoors.

    The quick and easy fix is to install a thin layer of compatible caulk on top of the failed caulk. That may work for a while.

    The best approach would be to dig out (or cut out) all of the old caulk and start from scratch. That's a more labor-intensive approach, of course.

  4. Stephen Sheehy | | #4

    I have polished concrete floors. I didn't put anything in the control joints. They look fine. I'd dig the caulk out and be done with it. Caulk always ends up attracting dirt.

  5. Expert Member
    Kohta Ueno | | #5
  6. Steve Hengeveld | | #6

    Martin, the slab is indoors.

    The cracks I'm seeing are almost 100% in the portion of the slab in the sun. Based on the comments, I have materials and/or workmanship that's just "good enough" for the portion that's shaded (and thus moves less), but fails in the portion that gets direct sunlight.

    My inclination is to wait the full year, then pull and replace the caulk that's exposed to the sun... and hope that fix is "permanent"!

  7. Expert Member
    Malcolm Taylor | | #7

    Your plan sound like a good idea. After that length of time you could also consider using coloured grout, rather than caulking.

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