Remove Moss from Your Roof
LESLIE: Got some mold on the roof. Tell us about it.
ELIZABETH: Yeah, I don’t really know what’s causing it. I mean in between our shingles there’s just mold growing.
TOM: Is it that big, thick, green moss?
ELIZABETH: It is green moss, yeah.
TOM: Yeah. Well, you know, there’s two ways you could fix this. You could get rid of it or you could simply mow your roof. (laughing)
TOM: That is caused just by a combination of conditions. I’d be willing to bet that this part of the roof is in a shady or damper spot. Is that correct?
ELIZABETH: It is. Yep.
TOM: Yeah. When you have a shady and damp spot, you get a lot of moss that grows because all of that stuff is floating around in the air and …
LESLIE: It’s perfect conditions for the growth.
TOM: Yeah. Well, you have all of the little moss seeds, so to speak, that are floating around in the air and they land on the roof and then they find a place and sort of grab onto that shingle and take root.
The good news is, Elizabeth, that it’s not hurting your roof shingles. It causes no damage to the roof. It’s just ugly.
Now, you want to get rid of it?
ELIZABETH: Yes, that’d be great.
TOM: Alright. Couple of things.
First of all, we’re going to have you wash the roof down with an oxygenated bleach.
TOM: Something you can pick up at a home center and mix up. This is a job that you need to do with goggles on and gloves, off a ladder, maybe with a pump sprayer and spray that area down with the bleach solution and let it sit for a bit. And then, you can gently scrub those areas and have the moss loosen up. You can also use a pressure washer on a light setting.
Once you get that roof cleaned up, to try to keep it from growing moss moving forward, there’s two things that you could do. Number one, if there’s any tree trimming that you could do that will shed some more light on that roof, the sunlight is a great moss killer. And that will stop …
ELIZABETH: Yes, it seems to only be on the west side of the roof.
TOM: OK, well – but if you have a lot of shade in that area, if there’s any way you can get more sun on it, that’s one thing.
The second thing is a bit of a trick of the trade and that is, you can get a piece of copper flashing or nickel flashing or you could use a copper or nickel ridge vent. Put it across the peak of the roof. And what’s going to happen is as rain strikes that piece of copper and then runs down the roof, the copper is going to release and that acts as a wash and it will actually clean the roof on the way down.
And if you want to see examples of this happening in real life, you drive an old neighborhood that has copper flashing around chimneys. You almost always see the roof streaked right underneath that. The reason for that is because the copper acts as a mildicide or as an algaecide and it cleans the shingles. So that’s a way to always keep the roof looking pretty clean; by having a copper or a nickel ridge vent. Works with nickel as well.