# Caulk for concrete floor **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 15, 2025, 2:37pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012 "2025-01-15T14:37:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 2:37pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/1 "2025-01-15T14:37:33Z")
Eh, we are getting pad and carpet installed over a bare concrete floor. It has some cracks in it. They are not getting bigger. The installation is in three days. I’m not worried about the cracks per-se, but the radon gas that could leak through them (we have not had a radon test) As a “Well it can’t hurt ‘fix’ (I use fix loosely)” I thought I would fill the cracks with caulk. Probably doesn’t matter, but what do you folks think, silicone or latex? I don’t really see a benefit either way. I’m in NO way thinking that this will keep the cracks from spreading. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 2:51pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/2 "2025-01-15T14:51:55Z")
May have answered my own question - [Concrete crack filler.](https://www.thespruce.com/the-best-concrete-crack-fillers-of-2023-or-by-the-spruce-7153229?utm_term=how+to+seal+cracks+in+concrete&gad_source=1&gclid=Cj0KCQiA1p28BhCBARIsADP9HrPsoZdjE1ZSO4YiYv_QFPwkrMnaZfJe2GrM4bRVWHfnpQcU-3patAcaAqxREALw_wcB&utm_campaign=commerce-dd-ConcreteCrackFillers_TheSpruce_Combined_CommSEM_OrganicLP-7153229&displayPrice=no&utm_medium=con&utm_test=&utm_source=googlepaid&utm_content=Cj0KCQiA1p28BhCBARIsADP9HrPsoZdjE1ZSO4YiYv_QFPwkrMnaZfJe2GrM4bRVWHfnpQcU-3patAcaAqxREALw_wcB) ---
**Author:** ![Sauron](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sauron](https://boards.straightdope.com/u/Sauron)\ **Post date:** [January 15, 2025, 2:59pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/3 "2025-01-15T14:59:09Z")
Yep, I was just about to post something similar – masonry crack filler sounds like the product you want. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [January 15, 2025, 3:05pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/4 "2025-01-15T15:05:14Z")
What they said. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [January 15, 2025, 3:24pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/5 "2025-01-15T15:24:03Z")
Have you considered a vapor barrier on top of the concrete (and under the carpet+pad)? Will help with moisture transfer _and_ radon: > **[Concrete Vapor Retarders: Everything You Need to Know](https://www.wagnermeters.com/concrete-moisture-test/concrete-info/getting-the-vapors/)** > > A concrete vapor retarder is any material that prevents moisture from entering a concrete slab. Vapor retarder are used to avoid flooring problems. ETA: that link was for _under_ the slab. Here’s one for _over:_ > **[Vapor barrier on top of slab - GreenBuildingAdvisor](https://www.greenbuildingadvisor.com/question/vapor-barrier-on-top-of-slab)** > > Hi _Over_ is really for cases where you’re sure there’s no vapor barrier _under_ the slab 😉 ETA2: another cite: > **[What is a Moisture Barrier and When is it Needed for Flooring?](https://www.flooringinc.com/blog/what-is-a-moisture-barrier)** > > When installing new flooring, do you need a moisture barrier? By learning how and when vapor barriers work, you can find out! ---
**Author:** ![filmore](https://avatars.discourse-cdn.com/v4/letter/f/7993a0/32.png) [@filmore](https://boards.straightdope.com/u/filmore)\ **Post date:** [January 15, 2025, 3:31pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/6 "2025-01-15T15:31:23Z")
Crack filler isn’t necessarily permanent. When I’ve used it on driveways and patios, it eventually shrinks and separates from the sides of the cracks. That’s not such a big deal on a driveway, but it may matter if you’re trying to block gases from rising up. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 3:42pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/7 "2025-01-15T15:42:26Z")
> [@filmore](#): > > Crack filler isn’t necessarily permanent. When I’ve used it on driveways and patios, it eventually shrinks and separates from the sides of the cracks. That’s not such a big deal on a driveway, but it may matter if you’re trying to block gases from rising up. I saw that in my mom’s driveway. > [@DavidNRockies](#): > > Have you considered a vapor barrier on top of the concrete (and under the carpet+pad)? I’ll have to think about that. Thanks. ---
**Author:** ![We\_re\_wolves\_not\_werewolves](https://avatars.discourse-cdn.com/v4/letter/w/838e76/32.png) [@We\_re\_wolves\_not\_werewolves](https://boards.straightdope.com/u/We_re_wolves_not_werewolves)\ **Post date:** [January 15, 2025, 3:43pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/8 "2025-01-15T15:43:26Z")
> [@filmore](#): > > Crack filler isn’t necessarily permanent. When I’ve used it on driveways and patios, it eventually shrinks and separates from the sides of the cracks. That’s not such a big deal on a driveway, but it may matter if you’re trying to block gases from rising up. this is true, but in a temperature controlled basement, you don’t have to worry about freeze and thaw cycles, and thus, while not technically “permanent”, you should not have these types of issues in this application. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 4:00pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/9 "2025-01-15T16:00:27Z")
Thanks everyone. Going to sell the place in a year or two. I suspect they will do a radon test 😬 We should have done one years ago, life got in the way. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [January 15, 2025, 4:15pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/10 "2025-01-15T16:15:39Z")
> [@enipla](#): > > I’m not worried about the cracks per-se, but the radon gas that could leak through them (we have not had a radon test) This is so backwards it hurts. Get the baseline radon tested before you schedule the carpet and padding and before your mitigation attempts. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 4:40pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/11 "2025-01-15T16:40:50Z")
Yes, I understand. If we have to pull up the carpet, so be it (It’s one room). The carpet is coming Monday. So no time for a test at this point. Should have thought of it sooner. My Wife just brought it up this morning. She’s an appraiser, so she deals with this stuff. That’s not my field at all. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [January 15, 2025, 4:42pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/12 "2025-01-15T16:42:15Z")
Are you in an area where radon is a common problem? ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [January 15, 2025, 4:48pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/13 "2025-01-15T16:48:53Z")
> [@enipla](#): > > She’s an appraiser, so she deals with this stuff. Heh, I suppose that’s one of the ONLY reasons to skip the radon testing: you can’t disclose what you didn’t know. Do you think the crack filler you haven’t bought yet will be dry/cured enough to be sealed under carpet in a few days? ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 4:58pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/14 "2025-01-15T16:58:28Z")
> [@TriPolar](#): > > Are you in an area where radon is a common problem? Not from anyone I know. But maps say it is a problem in Colorado. We don’t have a basement, this is a slab on grade. I suspect that that might mitigate it some. If there is even a problem. > [@jnglmassiv](#): > > Do you think the crack filler you haven’t bought yet will be dry/cured enough to be sealed under carpet in a few days? Yes I do. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [January 15, 2025, 5:28pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/15 "2025-01-15T17:28:26Z")
He’s in Colorado, where – broadly – half of all homes have high levels of radon. > **[EPA encourages Rocky Mountain and Great Plains region residents to “Test Your...](https://www.epa.gov/newsreleases/epa-encourages-rocky-mountain-and-great-plains-region-residents-test-your-nest-and)** > > EPA News Release: EPA encourages Rocky Mountain and Great Plains region residents to “Test Your Nest” and reduce home radon levels Instead of a test, or an active radon mitigation system, when you buy a home in Colorado, you get [**a brochure about radon**](https://oitco.hylandcloud.com/cdphermpop/docpop/docpop.aspx) – a document that few living human beings have ever read or will ever read. At scale, requiring every new home to have an active mitigation system would cost very little. Lung cancer, on the other hand, is both costly and shitty. I think the whole thing is just a wee bit insane, but … that’s just me. ---
**Author:** ![Tride](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tride/32/13907_2.png) [@Tride](https://boards.straightdope.com/u/Tride)\ **Post date:** [January 15, 2025, 8:32pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/16 "2025-01-15T20:32:25Z")
Plus you work for the county and most CO county health departments will loan you a radon tester for free (you dingbat! 🙃) ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 8:38pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/17 "2025-01-15T20:38:15Z")
Yup, my bad. They would. Never got around to it. Honestly, it may also be a situation where, I don’t really want to know. 32 years in this house with no ill effects. ---
**Author:** ![Tride](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tride/32/13907_2.png) [@Tride](https://boards.straightdope.com/u/Tride)\ **Post date:** [January 15, 2025, 8:41pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/18 "2025-01-15T20:41:39Z")
I hear you–out of sight out of mind is a truism for a reason. Plus it’s not super easy to mitigate radon in existing construction that doesn’t have a crawl space. But it might become an issue when you sell as you are aware. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 15, 2025, 9:02pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/19 "2025-01-15T21:02:08Z")
In Durango, if your house wouldn’t have a Radon problem naturally, the builders after WWII might have created one: [https://www.durangoco.gov/DocumentCenter/View/16139/Uranium-Mill-Tailings-Fact-Sheet](https://www.durangoco.gov/DocumentCenter/View/16139/Uranium-Mill-Tailings-Fact-Sheet) ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [January 15, 2025, 9:16pm UTC](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012/20 "2025-01-15T21:16:58Z")
> [@Tride](#): > > But it might become an issue when you sell as you are aware. Yeah, we are going to sell, one way or another. Cross that bridge when we get there. I’ll just go with ignorance, since, I. Don’t. Know. The concrete filler is sort of a ‘Might as well’ as long as it’s exposed. [Next page](https://boards.straightdope.com/t/caulk-for-concrete-floor/1013012.md?page=2)