How to Clean Efflorescence from Cement Slab Floor
LESLIE: Now we’ve got Bonnie in California. Welcome to The Money Pit. How can we help you today?
BONNIE: We have a condo that we’ve – it’s been rented for 12 years. And when our renters moved out, we were going to sell it. And we saw stains on the carpet and we thought, “Well, we’ll pull up the carpet, replace it and just paint and clean up and put it up for sale.”
BONNIE: Well, when we pulled the carpet back, the cement slab – it’s a cement slab, single-level condo, 1,600 – almost 1,700 square feet with a cement-slab floor. And when we pulled back the carpet, we found that it was very damp and there was that white, fuzzy kind of effervescence or whatever they call it that comes up from the cement.
TOM: Efflorescence. Mm-hmm.
BONNIE: Lots of that. We tore up all the flooring and thought, “Well, we’ll go ahead and hire a contractor and have it all fixed and put new stuff down.” And it didn’t dry out; it just was damp.
But in any case, this problem is not getting solved. We have – we don’t know where to go from here. We want to figure out if there’s some way to seal that floor that is going to keep it from, you know, ruining the carpet and wood again and get it for sale. But fix it so that it’s – so that we can say it’s fixed.
TOM: Alright. Well, here’s what I think is going on, based on your description. If you’ve got that much of a water source that close to the concrete slab – concrete is very hydroscopic. I mean it will really absorb water like crazy. And so if the ground outside is saturated, that is clearly drawing through the concrete into the interior and that’s why the floor has been so wet. My concern is that this could develop, if it hasn’t already, into a mold problem.
The bad news for the condominium association is that if they’re responsible for the structure of this building, which would include the floor, this is their problem to fix, not your problem to fix. And if I was advising them, I would tell them to stop calling contractors to check leaking ponds and start calling professional engineers that can analyze the building and figure out exactly what’s going on and prescribe the proper fix. They’ve got to think big here, not think small. Because I think they have a lot of liability, because it’s probably not you; you just happen to be the one that found it. But if your neighbors start pulling up carpet, they’re going to probably find the same thing.
All that you can do on the inside is really stop-gap. You can clean up the efflorescence, you can put a masonry sealer on the floor. But the problem is that that concrete is going to continue to get wet, continue to get damp and eventually it’s going to pull back into the unit. So, I think that you need to have a very serious sit-down with that condominium association.
BONNIE: Mm-hmm. OK.
TOM: Alright? Good luck, Bonnie.
BONNIE: Thank you very much.
TOM: Thank you for calling us at 1-888-MONEY-PIT.