Roof Cleaning in Seattle, WA
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At Clearly Amazing, we handle the roof so you can stay on the ground.
RESIDENTIAL SERVICES
Clearly Amazing provides roof and gutter cleaning throughout Seattle. Our crews treat moss and lichen with a low-pressure cleaning solution instead of pressure-washing equipment. More than half of Seattle’s housing predates 1980. We can clear the gutters after a roof cleaning.
Seattle’s wet months and tree canopy
Extension plant pathologists at Washington State University write that western Washington and Oregon’s cool, cloudy, wet weather is ideal for moss, lichen and algae on trees and shrubs. Seattle’s 2016 canopy assessment found that 72% of the city’s tree canopy is deciduous and 28% is coniferous. Residential areas, which cover 67% of the city’s land, held 72% of that canopy in 2016. Citywide, canopy cover measured 28.1% in 2021.
Seattle–Tacoma International Airport’s NOAA normals for 1991–2020 put November through January at about 17.81 inches combined, about 45% of the year’s total, while July sits at the low end with just 0.60 inches.
What moss and lichen actually do to a roof
Clearing heavy moss off a roof helps guard against the trapped moisture and lost granules that come with it. ARMA, the trade association for asphalt roofing manufacturers, says only trained professionals should clean an asphalt roof. GAF, CertainTeed and Owens Corning also advise against power-washing an asphalt roof. ARMA also notes that cleaning results are temporary and discoloration may recur.
Call (425) 353-6368 for a free on-site estimate in Seattle, or request one online.
Rinse water from a roof falls under the City’s rules too. Seattle’s Stormwater Manual gives cleaning and washing work its own best management practice, and it says pollutants loosened by cleaning should not be discharged to the public drainage system or to receiving waters. Among the pollutants the manual lists are soaps, detergents, surfactants and suspended solids. On every roof job, we manage the runoff path.
When to schedule roof cleaning in Seattle
Summer is the best window: June through August are the driest months at Sea-Tac, and the roof is dry to work on. Other times work too — a house about to list, storm debris scattered across the shingles, or moss that’s gotten too visible from the sidewalk to ignore. A cleaning in late summer means the roof starts November, the wettest month at Sea-Tac, already clear.
Moss and lichen come back as long as the shade and rain do, so we treat roof cleaning as ongoing roof maintenance rather than a one-off job. We’d plan on every few years, depending on shade.
Areas we cover
Our roof crews reach Seattle proper plus Kirkland, Bellevue, Redmond, Bothell, Renton, Issaquah, Everett, Lynnwood and Snohomish.
Common questions from Seattle homeowners
Is pressure washing bad for asphalt shingles?
ARMA’s published guidance calls for a low-pressure rinse, never a pressure washer, and the major shingle makers back that up with their own advice against power-washing.
How often does a Seattle roof need this?
Every few years, depending on shade. A roof that sits in shade most of the day belongs at the shorter end of that range.
Can I clean my own roof?
It can be done, but wet moss is very slippery underfoot, and ARMA recommends that only trained professionals clean an asphalt roof. On a steep Seattle roof, that tips the balance toward calling a crew.