Solve Attic Mold With Proper Ventilation
LESLIE: Next up, we welcome Al from Pennsylvania who has mold in the attic.
Al, I’m going to ask you a question. Do you have a bathroom vent fan? Because sometimes we see the exhaust fans venting into the attic, which would cause mold.
AL: Well, it’s kind of a white film on it and it started with one end and it started to spread to the middle where I found that I didn’t have any air ventilation from the peak. I had two vents but no – in each gable end but no cut hole in the peak of the – in the house. And I didn’t know what in the world to do about this situation, so that’s why I called in and see if I can get some help and some guidance on how to get rid of this stuff.
TOM: How old is your house, Al?
AL: It’s dated back around 1880, 1890.
TOM: Well, when your home was built, ventilation in the attic was not an issue because the entire house was so drafty that we didn’t have to worry too much about that sort of thing. But today it’s more of a concern. I’m going to give you sort of the standard way to ventilate an attic today, to make it work as efficiently as possible, and that’s with a combination of not one but two vents. It’s called a ridge vent and a soffit vent.
Now the ridge vent goes down the peak of the roof – that’s the ridge of the roof – and it opens that area up and that’s important because that area is where a lot of the heat wants to escape and it’s also an area that becomes depressurized as wind blows over your roof. So think of that as the exhaust vent.
LESLIE: Is it a continuous vent that goes across the entire ridge or is it in sections across the ridge?
TOM: No, it’s actually a continuous vent that goes across the entire ridge. What you do is you remove the cap shingle that goes across the ridge and then you cut like a 1-inch hole in the roof right down that peak and you stop short about two feet from each end of the roof. And then you put a ridge vent which goes down the whole length and overlaps that cut by about another foot, so it ends up being sort of stepped in from the end of the roof but it overlaps that cut by about a foot and then that’s the complete ridge vent.
AL: OK, I’m going to throw a twist in there. I have a metal roof.
TOM: Ah. OK.
AL: (chuckles) Didn’t mean to go through all of that but I understand that. With this metal roof, I looked up at the peak and I saw tar paper underneath the metal, so I cut a piece of the tar paper out, which allowed air to flow in. But I don’t think that worked at all.
TOM: Well, this metal roof, is it sealed at the top?
AL: Yes. It’s an odd metal roof. I’ve never seen this before.
TOM: Well, the principle still applies that you’ve got to have ventilation because you have wood framing under that metal roof and if you don’t vent it, that’s where you’re going to get the decay.
AL: Yes, this is very true.
TOM: So what you need to do is to try – OK, so maybe you can’t do a standard ridge vent with an asphalt shingle roof but you’re going to have to find a way of putting upper venting in there. But the other side of this is to couple this with overhang venting; soffit venting. Is there an overhang on the house as well, Al?
AL: Yes, there is.
TOM: So that’s an area that you want to put intake vents because here’s what happens. When you have the vents mounted near the peak of the roof and vents mounted near the soffit, the air blows in the soffit, underneath the roof and out towards that ridge area. So you need to create that circulatory pattern. That’s the best way to stop mold from growing.
AL: Oh, OK. Is it – I had understood from a friend of mine that you could actually – I could spray it with Clorox. Would that help to begin to get rid of this?
LESLIE: Well, the bleach is a mildicide, so it’s going to kill the mold that’s already there but it’s not going to prevent it from growing new growth.
TOM: Exactly. You need to add ventilation to that. That’s the only way you’re going to get rid of that on a long-term basis. You can use the Clorox to temporarily clean it up but if you want to stop it from coming back you’ve got to wash that area of the underside of the roof with lots of fresh air and strategically-mounted ridge vents and soffit vents are the best way to do that.
AL: OK, I’m going to have to get with somebody to figure that out. But I really appreciate y’all calling me back and the information you put out. That’s great.
TOM: You’re welcome, Al. Thanks so much for calling us at 1-888-MONEY-PIT, 888-666-3974; proving that you can call that number 24 hours a day, 7 days a week and if we are not in the studio we will call you back and answer your home improvement question just like we just did for Al from Pennsylvania.