How to Clean Black Streaks on a Roof

Find out why the black streaks on the northern side of your roof are most likely algae and moss growths. Learn about an eco-friendly product called Wet & Forget that will help you clean the roof (as well as siding…

LESLIE: Mike in Pennsylvania is dealing with some stains on the roof. Tell us what’s going on there.

MIKE: Yeah, I have – on the kind of the northern parts of the roof on my house, myself and – as well as my neighbors have these black streaks. And it seems to be a part of the roof that doesn’t get a lot of sun. And my question was – you know, I guess, first of all, what is it? And then, secondly, is there a way that I can clean that myself, as a homeowner, or do I have to hire somebody to do some – clean that type of streak off?

TOM: Well, generally, those streaks are made up of algae or moss. And they happen more frequently on the north side of the roof because it’s a cooler side of the roof and there’s more shade there. And a product that you could use to address that is called Wet & Forget. It’s a concentrate and you mix it up, you spray it on the roof. And then slowly but surely, it kills the algae, it kills the moss, it kills any mold that’s there and cleans the roof. And so, within a very short period of time, you’ll find that the roof looks bright and shiny again.

MIKE: Oh, OK. Does that product come in an applicator where you can hook it up to a hose or you actually do have to get up on the roof?

TOM: Don’t believe it does. I think you have to mix it up and put it in a pump sprayer.

MIKE: OK.

TOM: And so you may have to get up there and just spray it down and let it sit. Follow the instructions. Their website is WetAndForget.com.

LESLIE: Yeah. And it is a product that once you get it on the surface, over time it continues to work, so it’s not something that you’re going to have to reapply very often. So it is worth it if you can get up there to carefully spray it.

MIKE: Oh, OK. Would that also – I have the same problem with the siding on the northern part of my house; it gets a lot of that.

TOM: Yep. Absolutely. You could use it for siding, for sidewalks and for roofs. And the nice thing about Wet & Forget is it doesn’t damage your landscaping.

MIKE: Oh, OK, OK. Great, great. OK. Well, I greatly appreciate the advice. Thank you very much.

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