Get Rid of Mold and Moisture in a Crawl Space
LESLIE: Now we’re going to go to Tennessee with Randall who’s got a mold situation.
Randall, what’s going on?
RANDALL: I had a water leak underneath my house I didn’t know about – went on for about two months before I actually found out about it – and we started smelling mold. Well, I got the water leak fixed and it has dried up under my house and I sprayed the underneath of the house with a bleach solution; the mold and mildew under there.
TOM: (overlapping voices) So far so good. OK.
RANDALL: But I’m still having a mildewy-type odor.
TOM: OK. Well, you’re probably not smelling the mold; you’re probably just smelling moisture.
TOM: Now, tell me about where this leak occurred, again.
RANDALL: It was underneath my house. I have a crawlspace.
TOM: Crawlspace? OK. And the crawlspace is now dry?
TOM: Alright. Have you looked at your drainage conditions at the foundation perimeter? Because even though you don’t have flooding, if you have flat grade around the house or if you have gutters that are dumping right at the corners, you’re going to elevate the amount of moisture that’s getting around the foundation and concrete is very hydroscopic – that means it soaks up the water – and the inside surfaces act like evaporator pads where the water basically evaporates into the air space and creates that mildew, moldy smell. So I want you to look at that …
RANDALL: Solved that problem. I put up gutters and I even graded – I put extra soil up around the perimeter of the house.
TOM: What kind of soil did you add?
RANDALL: Well, it was just a topsoil.
TOM: Wrong soil.
LESLIE: Is that just letting it permeate more down into the foundation?
TOM: Exactly. Topsoil is organic. It’s designed to make stuff grow. It’s a lousy drainage soil. What you want is something called fill dirt.
RANDALL: Ah, OK.
TOM: OK? Now, it’s a sand floor, of the crawlspace?
RANDALL: No, it’s a clay-type soil.
TOM: Clay-type soil? And do you have anything on top of the clay-type soil? Do you have any – do you have a plastic vapor barrier down?
RANDALL: I do not. I was wanting to get rid of this problem before I put the …
TOM: Put the vapor barrier down now. That’s going to stop some of that water from evaporating from the soil in.
Now, the last thing I’m going to suggest is this. Do you have vents in this crawlspace?
TOM: What you might want to do is get a power ventilator. A power ventilator actually replaces one of those vents and it’s like a fan and it’s wired to your humidistat so that whenever the moisture level comes up in the crawlspace, the power ventilator kicks on and draws dry air from the outside through the crawlspace by kind of depressurizing it and all that moisture goes out with it. If it’s tied to a humidistat, it’s only going to come on when it gets wet and that’s exactly the time that you do want it to come on.
RANDALL: Great. OK.
TOM: OK? So I think those are the issues. I don’t think you’re smelling mold. I think you’re just smelling moisture and you need to do a better job at managing it.
RANDALL: Thank you very much.
TOM: You’re welcome. Thanks so much for calling us at 1-888-MONEY-PIT, 888-666-3974.