Install Unfaced Insulation Over Blown-In Insulation
LESLIE: Well, now we’re going to take a question from Steven in Minnesota whose question is about insulation. So my only guess is that you’re freezing your buns off, Steve.
STEVE: Well, I’ve been living in this house for about 15 years and it’s never been a very warm house, so I’ve been insulating the walls and such. And then I got to the attic and I noticed that it’s got blown-in insulation that’s settled way down and so I decided to beef that up. They recommend an r 38 up in this part of the woods. And so I – I was putting some insulation up in there and I noticed, when I started reading up on it, that I would need unfaced insulation in there.
STEVE: Yeah, that makes sense but I’d already installed some faced insulation down because I could get it over into the corners.
TOM: Oh, boy. Which way did you face the vapor barrier?
STEVE: I faced it down; the paper down.
TOM: The paper is down; the insulation is up. And is that a second layer of insulation?
STEVE: Yes. It’s over the …
LESLIE: It’s over the blown-in.
TOM: Oh, man.
STEVE: The blown-in stuff.
TOM: Yeah. I got bad news for you, Steve. You’re going to have to pull that out. If it – because it’s basically sandwiched in between. And what you’ve done now is you’re going to trap moisture beneath that paper and the blown-in will become saturated and it could develop condensation and mold problems because what happens is you get dust on the insulation and that feeds mold and the mold will grow on the insulation strands.
LESLIE: And also, as the insulation gets moist, you’re cutting down its r value; you’re making it sort of not do its job, correct?
TOM: Yeah, that’s right. You know, it may not be a terrible job. What you’re probably going to want to do is pull that insulation out there. You can even peel off the paper face – it’s not a pretty job but it’ll work – and then lay those batts back down as unfaced; then you’ll be good to go. And you’re right; you need about 22 inches of blown-in or about 19 inches of unfaced insulation in that attic space to give you the maximum amount of warmth.
STEVE: OK. Well, I guess I’d better get myself back up in there then.
TOM: Yeah. Basically, Steve, you created a moisture sandwich there and we’ve got to fix that.
STEVE: OK. Well, that sounds like something I can probably work on this next weekend.
TOM: That sounds good. Steve, thanks so much for calling us at 888-MONEY-PIT.