Mold on Radiant Barrier Insulation – Treat or Replace?
LESLIE: Alright. Next up, we’ve got Edward in western Pennsylvania who’s got a question about insulation. What can we do for you?
EDWARD: Yes. The rolled-type insulation that’s like a thin film, they call it a “space-age product” that was made that you can’t actually even rip. And it’s supposed to hold the heat in the house, like in an attic. It’s installed in my parents’ house and now there seems to be a problem on the – actually, between the rafters. I noticed it on the sheathing. It’s got a white mold. Not a lot but just a tinge of a white mold that’s appearing. Does this cause a moisture problem in the attic of that house?
TOM: OK. So, first of all, what you’re talking about is called a “radiant barrier.” And I’ve personally not experienced them to be very effective. In fact, the Department of Energy says on their website that some studies – some studies – show that they can reduce cooling costs by 5 to 10 percent when used in a very warm climate.
So, for my money, it’s generally not worth it. So if this now is trapping moisture so that the insulation is getting damp – if that’s what’s happening, that’s a bad thing because insulation has to be dry to be effective. So, I wouldn’t be terribly upset if you took it down.
EDWARD: I see. They actually installed this on the floor. It’s a floored attic and they installed it on the floor.
TOM: What’s underneath it?
EDWARD: There is insulation under the – most of it. But where it was floored, I doubt whether there is. And nobody has ever taken that up to look.
TOM: So, you say this is on the floor. So, you can walk on it?
EDWARD: Yeah. You’re walking, actually, on it in the attic.
TOM: It’s like a foil, right?
EDWARD: Yes, it’s like a very heavy foil and you can’t rip it.
TOM: So, I – so your question is: should you leave it in place? Does it make a difference? Is that what you’re asking me? And you say it’s starting to tinge?
EDWARD: Right. And is this going to cause, do you think, a mold issue that could get worse in time?
TOM: The thing is, if it’s serving as a vapor barrier, it’s basically on the wrong side of the insulation.
EDWARD: I gotcha.
TOM: Because vapor barrier goes between the heated and the unheated space. So if it’s on top of the insulation, then it definitely could trap moisture. Because warm, moist air is going to come up from your house and get stuck in that insulation and not ventilate out. You follow me?
EDWARD: Right, right.
TOM: It doesn’t make a lot of sense, Ed.
EDWARD: OK. Thank you.
TOM: Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.