Improve Attic Ventilation to Prevent Black Spots
LESLIE: Judy in Iowa, you’ve got The Money Pit. What can we do for you today?
JUDY: I’m in a house that my father built back in 1990.
JUDY: And while they lived there, they experienced black spots coming through on the drywall.
JUDY: And they called in a painter; a painter came in. He went over everything with KILZ first and painted it. Well, since then, they’ve both passed away and so I purchased the house.
JUDY: I had a friend take a look up in the attic and he told me, “Oh, I can’t believe that your father wrapped all this in plastic. Your house can’t breathe. We need to get up here and slice this plastic, let the house breathe and you won’t get any more of these black spots.”
TOM: So does he think the black spots are mold?
JUDY: I don’t know.
LESLIE: And what room were you seeing it in?
JUDY: Every different room. Yeah.
JUDY: It’s almost like it’s the nail heads are getting wet or something.
TOM: OK. So, up in the attic – let’s talk about that area. And you say he wrapped it in plastic. What exactly are you seeing?
JUDY: Well, I didn’t; I haven’t been up there.
TOM: Oh, your friend saw it.
JUDY: My neighbor went up.
TOM: Alright. Well, look, when it comes to vapor barrier, here’s the rule: the vapor barrier goes towards the heated side of the house. So a common mistake, for example, up in attics, is to put the insulation in backwards where they have the vapor barrier sort of facing up as you’re in the attic looking down.
And the solution to that is to cut the vapor barrier. I’ve seen that in crawlspaces, too, where they put the vapor barrier because it has the nailing flange on it. And they only tap on it at the edge of the beams and it’s on the wrong side. So, as long as the vapor barrier is between the ceiling and the insulation, it’s done correctly. If not, then yes, you can go up and slice the vapor barrier and let it breathe more.
The other thing to do is to make sure that your attic has adequate ventilation. And the best ventilation is a continuous ridge vent, which goes down the peak of the roof, matched with soffit vents at the overhang.
JUDY: OK. That’s what I needed to know.
TOM: Thanks so much for calling us at 888-MONEY-PIT.