Adding Blown-In Insulation in an Attic
LESLIE: We are about to take a call from Jim in West Virginia who has a question about blown-in insulation.
Jim, what do you want to know?
JIM: Well right now I have six inches of fiberglass insulation in my attic. I’d like to blow another 12 inches. I want to know if my wallboard, my flasher board, will carry that weight.
TOM: Oh, absolutely. It’ll carry the weight. But there are some other concerns that you should be aware of. Do you have any high-hat light fixtures, the flush light fixtures that are mounted into the ceiling that you’re going to be blowing this against?
TOM: OK. So that’s not an issue. The second thing is at the edge, at the roof edge, you want to make sure that you provide for proper ventilation, Jim.
LESLIE: To avoid ice damming.
TOM: Exactly, ice damming and to make sure that the attic stays nice and dry in the winter and cool in the summer.
JIM: Yeah, I have a ridge vent and I also have vents along the outside edge.
TOM: Right. Now the soffit vents is what we’re talking about. What you must – probably will have to do is to install something called an insulation baffle. It basically keeps that soffit area open so it doesn’t get clogged when you put all this extra insulation against it.
JIM: Talking about that piece of fiberglass or plastic.
TOM: Yeah, it’s either cardboard or it’s Styrofoam or it’s plastic and it’s like a chute and it leaves the airflow kind of open from the soffit. Once that’s in place, there’s absolutely no reason you cannot install blown-in fiberglass and, in fact, it’s a wonderful idea. And the numbers you’re talking about are about right. In other words, you have 6 inches now – we all know that’s not nearly enough – and you’re going to add about 12 inches of insulation to that, so now you’ll have about 18. That’s terrific and that’s going to do a good job.
Jim, thanks so much for stopping by The Money Pit.