How to Keep Moss from Growing on a Roof

Find out why the best weapon to prevent roof moss from forming is sunlight. Get tips on how to thin trees to let enough sunlight reach the roof to prevent the growth of moss and algea, as well as what…

LESLIE: Mary in North Carolina is on the line with a mossy roof. Tell us what’s going on at your money pit.

MARY: Well, we have a 10-year-old roof – asphalt shingles, I believe they are – and the sections between shingles are beginning to be filled up with moss.

LESLIE: It’s like a mossy grout line.

MARY: Yeah, that’s right. I’d like to know how to get it safely clean and keep it from growing back again. It isn’t the entire roof. We are in an A-frame house, so it’s very sharp, very steep roof. And it’s just about the 8 or 10 feet closest to the edge.

LESLIE: OK. Do you see it all the way around or do you just see it on, say, the north-facing side or in the area …?

MARY: It’s just on this north-facing part.

LESLIE: OK. So that’s the area that gets the least amount of sunlight.

MARY: Right.

LESLIE: Do you have a large tree that’s adding more shade to this area?

MARY: We have a lot of trees, yeah.

LESLIE: A lot of trees.

TOM: Yeah, therein lies the problem.

LESLIE: Mm-hmm. Now, I mean the best solution here is – can you trim out or thin out those trees in any way to get more sunlight onto that portion of the roof? Because if you can do that, sunlight really is your best weapon in getting rid of this moss and keeping it away. Now, you’ll have to do some work to get it to be gone in the first place but if you can add more sunlight, you’re going to help it stay away.

MARY: Alright. Very good. Thank you very much.

TOM: Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.