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Question DetailsAsked on 9/9/2013

How much should I expect to pay to have moss removed from roof?

Roof is pitched and has hooks to harness worker.

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3 Answers


This is a tough one to estimate without seeing it - I am going to assume not steeper than 6:12 pitch - if general light moss, maybe $200 range plus or minus about $50 assuming you are talking a asphalt shingle roof of typical size (roughly 30x50 or less). If heavy moss (clumps rather than tufts and fuzz), then probably 50% more. This assumes hose with nozzle washing and stiff brooming CAREFULLY so as to not remove the granules from the shingles or cut the shingles (NOT pressure washing - do NOT trust anuyone on your roof with a pressure washer other than yourself), with localized wire brushing to get the growth from between the cutouts (notches) in the shingles. If you are talking hand wire brushing every cutout for an entire roof, then more like $400-500. If you ae talking very steep pitch so unwalkable - say 8:12 or more - then about 50% higher cost.

If you have a significant moss problem, you should be looking at three things:

1) cutting back trees that heavily shade or deposit organic material on the roof - can cut roof life by about 25% if removed annually, up to 75% if allowed to build to significant thickness.

2) sprinkling MossOff or similar zinc powder over entire roof after moss is manually removed and rinsed off and roof is still wet - about $20 a can which covers about half to 2/3 a normal roof area. If roof is over about 6:12 pitch I would go with the spray kind rather than powder, as powder will just wash right off in first rain.

3) install zinc coil strip under the top row of shingles (not including ridge vent shingles) - get the 4-6" wide coil so there is a lot of exposed zinc - about $40-60 for 50' roll, plus some galvanized shingle nails, bitumastic caulk (to put under nail heads) and about 1 hour labor for typical house. Be sure to stick toip edge well up under shingle above it, and nails should be tucked under the overlying shingle as much as possible. Combined with an annual hosing off, this will kill moss and most lichen for decades.

If you have ornamental shrubs within the direct (say 20 feet or so) runoff zone of the roof - either directly or via the downspouts, the zinc can injure or kill them, and can damage (rarely kill) lawn, especially for the first 2 rains after the zinc powder application.

Answered 4 years ago by LCD


Thanks LCD. What if the roof also has black algae on it - wouldn't that require pressure washing? Not sure that brush would do the job. Thank you, again.

Answered 4 years ago by Guest_98722626


The algae is too thin and tenacious for washing to get it off - you need to kill it, preferably first so it gets removed with the moss.

In the long run, the zinc strip at the ridge will kill it, and copper strip actually does a better job for algae and lichen than the zinc, which works best on moss. I guess you either have to decide which is more important, or maybe use the zinc powder (MossOut - I mistakenly said MossOff, which is an organic product that works but not as well) and copper strip, though purchase cost for that is about $100 for 50 feet versus $35-50 for zinc. Or go the other way if the moss is the major problem (the algae does not significantly damage roofs as moss does), and use the cheaper zinc strip and a copper-based granule or spray to kill the algae right off.

NOTE - zinc is corrosive to copper, so if you use both zinc and copper strips the copper should be the top one on the roof, and don't sprinkle zinc granules uphill of it. Also, bleach will neutralize the zinc or copper granules and react violently with the strip, so they should not be applied till after the bleach has been used and then washed off with the cleaning. If you don't like the bleach use, there are alternative products like Roof Cleaner QSE and Roof Shingle CLeaner OX available.

If you want immediate kill, then you can use chlorine bleach (50% mix with water) sprayed on the roof to kill both the algae and the moss, let them sit a week or so to die, then the moss cleaning will go easier and also take most of the algae with it. Then coat the roof with the zinc MossOut powder as residual kill measure for the bits left behind, backup up long-term by the metal strip.

Before using the chlorine bleach wet plants and grass nearby, then wash them off right after. If really valuable plants, cover them and use oxygenated rather than chlorine based - still wet first and rinse after, but has minimal effect on plants in small quantities.

One note on the moss removal - be sure the contract includes picking the mess up off the ground and disposing of it, and washing out your gutters AND downspouts to get the moss clumps out or they will plug it up.

Answered 4 years ago by LCD

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