How to Prevent Roof Moss

Find out how to prevent moss from growing on your roof. Get tips on trimming back trees so the roof gets plenty of sunlight and installing a copper ridge vent to act as a mildicide when it rains.

LESLIE: Next up, we have moss on the roof gathering in Maine with Richard.

Richard, tell us about what’s going on?

RICHARD: Well, I’ve got an old building that’s underneath a tree and I’ve had moss growing on it. I’ve gotten the moss off and it comes back. I put a new roof on it. I’d like to find out how to keep the moss from even starting.

LESLIE: When you’re cleaning it, are you using any sort of mildicide or you’re just using water?

RICHARD: I use bleach and water and some soap in it.

TOM: Those are all good things to do. A couple of things that you can do. First of all, the more light, the more sunlight, you can get on that roof, the less likely it’s going to be that moss will grow. So if you can cut back the tree …

LESLIE: Trim back those trees.

TOM: Yeah, give yourself a little bit of light that pokes through.

LESLIE: And then if you have a really sunny day, apply that bleach/water solution because the sun actually helps to activate the bleach and will help it actually clean better.

RICHARD: Right. But now I’ve got a brand new roof on it with no moss on it and I was wondering if there’s a way to keep the moss from even starting.

TOM: Well, did you put a ridge vent on as part of this brand new roof installation?

RICHARD: Yes, I did.

TOM: And what’s the ridge vent made out of?

RICHARD: I mean it’s just a cap.

TOM: Oh, you mean the ridge cap of shingles.

RICHARD: Correct. That’s what I put on top of it.

TOM: OK. What I’m talking about is a ridge vent. That’s where you have the top – where that cap shingles is right now, there’s actually a slot there and it’s covered with a metal vent. If you put up a ridge vent, a metal ridge vent, that’s made of nickel or copper, what’s going to happen is every time it rains, some of that metal gets released and runs down the roof and acts as a mildicide and keeps the roof from building up moss.

Now if you don’t want to put the vent on, then just wrap the top cap shingle with a big, wide piece of copper flashing and it’ll do the same thing.

RICHARD: I appreciate it. That’s what I’ll do then.

TOM: OK. Thanks so much, Richard, for calling us at 1-888-MONEY-PIT, 888-666-3974.