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My basement floor patch keeps cracking after a few months | DIY Home Projects - Chatter Central

My basement floor patch keeps cracking after a few months

I used a concrete patch mix from the hardware store on a 2-foot wide hole in my basement floor about 4 months ago, and now there's a hairline crack running down the middle again. My neighbor said I probably didn't wet the edges enough before pouring it in. Anyone have a trick for making patches actually stay put in a damp basement?

3 comments

3 Comments

sam_thomas3mo ago

Oh man, I hear you on that. I've patched basement floors more times than I care to count. Sounds like your neighbor was probably right about the edges not being wet enough, but the bigger issue might be the concrete mix itself. Standard bagged patch has too much sand and not enough binder for a damp basement floor. Try grabbing a bag of hydraulic cement instead, it actually expands a little as it sets and holds tight in wet spots. Scuff up the edges of your hole with a wire brush real good, soak the whole area with water until it stops soaking in, then mix your hydraulic cement pretty stiff. Tamp it down hard with a scrap of 2x4 to get rid of any air pockets. That stuff cures in like 10 minutes so work fast. The other thing nobody talks about is expansion joints. If that patch is close to the wall you might need a little gap there to let it move without cracking.

gavin6923mo ago

Right, because nothing says "fun weekend project" like mixing concrete that sets harder than a toddler's resolve not to nap. I've been there with the standard bagged patch peeling up like a bad sunburn, so the hydraulic cement advice is solid. Just be ready to channel your inner surgeon, because once that stuff starts going off, you have exactly enough time to curse before it's rock solid. And yeah, expansion gaps are one of those things you only appreciate after your patch turns into a jigsaw puzzle from hell. At least with three kids running around, I've got plenty of practice tamping things down until they stay put.

oscar7433mo ago

Heard a contractor on a podcast saying the same thing about hydraulic cement and expansion gaps, that's probably your best bet. Sounds like @sam_thomas nailed it with the preparation steps too, so maybe try his method but leave a small gap near the wall next time.