Prevent Mold in Your Attic

Find out how to prevent mold from growing in your attic space. Learn how proper roof venting works and what to install to prevent attic mold from starting.

LESLIE: Baxter in Rhode Island’s up next and you’ve got mold in the attic. Tell us what’s going on? Where do you see it?

BAXTER: Oh, I don’t have mold. I’m just asking what to do to prevent it. I haven’t been up there and I was listening to one of your shows regarding preventing mold in the attic. My bathroom exhaust vent just goes into the attic but it doesn’t go all the way through the roof and I was just wondering if that’s a dangerous situation there for mold to occur.

TOM: Here’s what you need to do, Baxter. First of all, you need to take that bath exhaust fan and make sure it is ducted completely out of the house; that means into the attic and then out from the attic to the exterior. Now, if you can’t get a hole in your exterior, the least you should do is have it pointing right at the edge of one of those exhaust vents in the gable walls of the building.

The second thing that you might want to do is think about improving the roof ventilation by adding a ridge vent at the peak of the roof that goes up and down the roof and then, also, a soffit vent at the overhang. And the reason you’re doing that is because as the air pushes over that roof, it gets depressurized at the ridge so air will sort of suck out of the attic at the ridge and it’s pressurized at the soffit. So what’ll happen is the air will go in the soffit, under the roof sheathing and out the ridge.

And what’s great about that system, when you have it installed, it’s working in the summer, it’s working in the spring, the fall and the winter. So no matter if it’s, you know, really hot up there, making your air conditioning bills crazy, it’ll pull the hot air out. In the winter time, when you get moisture and condensation, that’s what causes the mold to grow on the inside of the roof sheathing; it can actually rot out the roof sheathing. It will save that from happening as well. So, get the bath exhaust fan out and improve the ventilation in the attic generally and you will not have any mold problems to worry about.

Baxter, thanks so much for calling us at 888-MONEY-PIT.