LESLIE: Heading out to Minnesota where we’ve got Trevor on the line. How can we help you today?
TREVOR: I have tongue-and-groove boards on my ceiling in my living room. I was wondering about replacing them and putting new ones up. And they’re starting to twist and gap and whatnot. And I was wondering if a person needs a vapor barrier behind there.
TOM: Yeah, there are a lot of advantages to spray-foam insulation and one of them is that you don’t need a vapor barrier. The concept of managing moisture with a spray-foam application is not the same as if you had fiberglass.
You need a vapor barrier in a fiberglass situation because you need to keep the moisture from building up in the fiberglass and making the insulation ineffective. But with spray foam, that’s not an issue. Basically, there is no sort of unconditioned space left, so it all becomes part of the conditioned space and therefore needs no ventilation, it needs no vapor barrier whatsoever.
TOM: So it’s pretty easy.
TREVOR: Some carpenters have told me that sometimes they put sheetrock behind there before you put tongue-and-groove boards up or something.
TOM: Well, yeah. Because the reason for that is because sometimes the tongue-and-groove boards will shrink. You’ll see gaps behind it. So that’s not a bad idea. It’s kind of your option, though, whether you do that or not. If you like the look of the tongue-and-groove planking on the ceiling, then that’s your call. But certainly, you do not need any kind of vapor barrier.
TREVOR: Oh. Outstanding. Perfect. Thank you very much.