Strong Musty Odor in the Basement
LESLIE: John in Connecticut, you’ve got The Money Pit. How can we help you today?
JOHN: OK. Well, we’ve got a problem here. The house was built in ’64. It’s a ranch; the garage is below. Part of the grade is like a raised ranch in the back.
JOHN: And I’ve always had a concrete, dusty, sheetrock smell to the basement. It’s this almost old – well, like old-home smell.
TOM: Right, OK.
JOHN: It reminds me of rubbing your towels on the concrete or – it gets in the bed sheets, it gets in the linens upstairs and the clothes.
JOHN: It’s completely throughout the house. I’ve had inspectors come in looking for mold or moisture or whatever. They checked normal moisture everywhere in the walls.
JOHN: There’s no evidence of any spotting or any kind of mold growing but it’s got this odor.
TOM: Right. And this is an unconditioned space of the house? In other words, there’s not – this is not – your heating system doesn’t extend to this area, John?
JOHN: Yeah, well, the boiler furnace is downstairs in the middle of all this.
TOM: Right. But the duct system is not – there’s no supply registers or return registers down there?
JOHN: Right. The duct system is only for the A/C and the A/C is up in the attic.
TOM: I see.
JOHN: And it’s a hot water-base heat.
TOM: This is a hot-water system.
JOHN: Yeah, a hot-water system.
TOM: OK. So, what’s the finish on the block walls now? Is it just wall?
JOHN: Right now, there may be some – the Waterplug paint or the water – actually, it’s just a green paint but it might have had – I know there was Waterplug, there’s other kinds of things they paint with but I think that’s about it.
TOM: Water-resistant paint? OK.
JOHN: And in the garage, there’s no finish. Part of the basement is closed off and that has a green, paint-like coating on the walls.
TOM: How long has it been like this? Has it always been this way or is this something that’s …?
JOHN: I think it has been. It’s been here since – ’64, the house was built. And I started coming here 20, 30 years ago.
TOM: Right. Alright. Well, I mean I suspect that you probably have – you would normally have higher humidity levels in that space. And because it’s a hot-water system, one of my theories was going to be that we could start to use some of that air in the return duct and move it through the house a bit; condition it. But that’s going to be impossible to do because the way your house is configured.
So, I would do two things. I would do everything possible to reduce the humid ity levels in the basement area and that’s going to happen at the outside edge of the house, by making sure that we have letter-perfect drainage conditions. On MoneyPit.com, there are articles on how to solve a wet basement. I realize you don’t have a wet basement but the same exact advice applies.
And it’ll give you step-by-step on things like cleaning gutters, extending spouts, making sure they’re designed properly, making sure there’s enough downspouts for the square footage of roof that you have. And then, secondly, the regrading of the foundation perimeter: sloping that soil away so we get perfect drainage at the outside.
The second thing that I would do is I would scrape, prime and repaint the interior of the foundation walls. And I would use a good, epoxy-based masonry paint for that. And then thirdly, I would add a dehumidifier down there. And there are humidifiers that are self-draining. So if you have the opportunity to drain it to a lower part – a sump pit, anything like that – or if not, you can get a humidifier on a condensate pump and lift it up and drop it into a drain wherever it’s available.
The other thing I would check is – and you said you had inspections. But I would just make sure that we take a look at the plumbing system. If for any reason there is a dried-out trap – for example, if you had a floor drain or some other type of drain down there where there was no water that was collected in that trap, which is the U-shaped part – that can let sewage gas back up into the house, from the house, from the street.
LESLIE: And that can be really stinky.
TOM: Yeah and that can be pretty nasty. So those are the basics that I would do to try to reduce odors down there.
JOHN: Yeah. Well, OK, that’s a great thing to try. Well, I’m telling you, I have installed a Humiduct. You know what that is?
TOM: Yeah but that’s not going to be very effective.
JOHN: OK. Well, I thought it was worth a try.
JOHN: And I put it in and it didn’t really do much.
TOM: Yeah. A dehumidifier is going to be much, much more effective. But manage the water from the outside first, because that really is the easiest way to stop – to slow down how much gets into the air.
TOM: Problem is that concrete-block walls are very hydroscopic. They’re like sponges; they soak up the water from the outside and then they release it into the basement. And that’s where you get kind of that heavy, damp, kind of musty odor.
JOHN: Yeah. Well, it’s a poured-concrete foundation.
TOM: Well, the same thing applies. It will release it up into the air.
JOHN: Yeah, they will. And I’ve got a – part of the basement is with vinyl tile.
JOHN: And underneath that tile is the white calcignificance (ph). Is that it?
TOM: Well, if you’re seeing white – you’re seeing that white, crusty, mineral deposits? Is that what you’re telling me?
JOHN: I don’t know if it’s mineral but it’s white powder underneath some of it.
TOM: That means you’ve got moisture. What you’re seeing is moisture that’s in the floor that evaporates and leaves the mineral salts behind. So that there is evidence that you have a moisture problem and the moisture problem can be resolved if you follow the exterior-drainage advice I just gave you.
TOM: Thanks so much for calling us at 888-MONEY-PIT.
JOHN: Thank you for your help. Bye bye.