Removing Roof Moss

LESLIE: Mike out on the east end of New York is calling us with a question about a roof. What can we do for you?

MIKE: Hi. I have an asphalt roof and I have an overhanging tree on one corner of it and that produces this green mold which, you know, is pretty typical when you have that and the sun can’t bake it off. But on an open, clear area of the roof, I get these black streaks that are coming down the asphalt.

TOM: OK.

MIKE: And I’m not sure what the – that is. I would imagine it must be some sort of mold or something but I’m not …

TOM: Well, it’s probably moss or mildew and sometimes when you get the black streaks, it’s because there is slight temperature difference – changes across the roof surface where you have a rafter that’s going to be cooler than when you don’t have a rafter. And so where you have …

LESLIE: And then what happens is the moss or the dirt is sticking to that area.

TOM: Right. You get a little more condensation; a little more stickiness right there and then it builds up. What you have to do is clean the roof with a mildicide. You can use a product like Jomax – J-O-M-A-X; that will clean that off. The other thing that you can do is to add some – either a copper or a nickel ridge vent to the peak of the roof. What’ll happen if you do that is as it rains, some of that metal will release and actually clean the roof every time it rains; it works very, very well.

MIKE: You know, that’s funny you say that because what I did do when we put the roof on – and this is going back about 10 years – I put lead – a lead …

TOM: Strip?

MIKE: … strip and …

TOM: Yeah, same thing. And how did that work?

MIKE: It didn’t. (chuckles)

TOM: It didn’t. (Leslie chuckles)

MIKE: I think it may have worked for a couple years.

TOM: Yeah.

MIKE: And then it just overtook it, you know. What …

TOM: Maybe. Yeah, you know, normally we recommend copper or nickel – not lead – but I know that some people do it with lead.

MIKE: (overlapping voices) OK. Uh-huh. Alright. I’ll give that a shot.

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