LESLIE: Now we’ve got Nick in Iowa on the line who’s building a new home and needs a hand. How can we help you?
NICK: Yeah, I was wondering if you could tell me the proper way to insulate the exterior walls and the vapor barrier of the inside.
TOM: Well, what are you – what kind of siding are you using?
NICK: Right now, probably vinyl.
TOM: Vinyl? OK. So, what you would do is you would insulate the interior walls. Do you want to use fiberglass?
TOM: Alright. So, you would use a fiberglass with a vapor barrier attached. So the vapor barrier always goes towards the heated space or the living space, so the fiberglass will create the vapor barrier on the inside surface on which drywall goes. Outside, you would use a product like Tyvek, which is a different type of vapor barrier that goes under the siding. That helps stop some of the air infiltration, as well.
So, basically, on the inside, you’re going to use the vapor barrier that’s attached to the fiberglass insulation. On the exterior, you’re going to use a building wrap like Tyvek.
NICK: So like a paper-backed interior insulation?
NICK: OK. Because they won’t let – in our area, they won’t let you put a vapor barrier like Visqueen or anything on the wall.
TOM: Well, you wouldn’t put Visqueen, because you want something that’s vapor-permeable.
LESLIE: And Visqueen is going to trap that moisture in and then cause mold.
TOM: Yeah. But you use the vapor barrier that’s attached to the fiberglass insulation. That’s the easiest way to go.
NICK: Oh, OK.
NICK: Great. Thank you.
TOM: You’re welcome, Nick. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.