Serving the Seattle Eastside
Roof Washing
Safe soft-wash roof cleaning that removes moss, algae, and lichen from PNW rooftops. Serving Sammamish, Issaquah, and the Eastside.
Moss on an asphalt roof is not a cosmetic issue. The root systems — called rhizoids — penetrate the surface of the shingle and physically lift the granules away from the mat. Once those granules are gone, UV damage accelerates rapidly. A roof with active moss growth is a roof that is aging faster than it should. Most roofing manufacturers in the Pacific Northwest void the warranty on roofs with untreated biological growth, because they know what we know: moss is a slow demolition crew working on your behalf.
Why Eastside Homeowners Choose PNW Softwash for Roof Washing
We use a low-pressure soft wash system — never a pressure washer on a roof. High pressure washing blows granules off the shingles and voids manufacturer warranties. Our biodegradable sodium hypochlorite solution kills moss, algae, lichen, and the black algae streaks (Gloeocapsa magma) at the biological level, not just at the surface. Dead moss dries and sheds naturally over the following 4–8 weeks, leaving a clean roof without the scraping and raking that damages shingles.
We treat every roof with a post-wash zinc or copper sulfate rinse to inhibit regrowth. Combined with the soft wash treatment, this extends the clean period significantly compared to a rinse-only approach.
The Difference Is Visible
Real results from homes across the Eastside.
Roof Wash — Issaquah Highlands
Roof Wash — Klahanie
Cedar Shake — Sahalee
Drag the handle to reveal the transformation. Real homes, real results.
What Our Roof Washing Service Includes
Our roof washing process: pre-wet all landscaping and downspouts to protect from runoff, apply soft wash solution at low pressure from ground or ladder (no walking the roof), dwell for 15–20 minutes, rinse with clean water, apply post-wash anti-regrowth treatment, remove all protective covers.
We carry full liability insurance specifically for roof work. Every technician is trained in manufacturer-safe soft wash protocols. We don't walk roofs on pitches over 6:12 without safety equipment — and we have it.
Pricing for a typical single-story home (1,800–2,400 sq ft footprint) starts at $350–$450. Two-story or steep-pitch roofs run $450–$600+. We quote based on roof square footage and pitch — you'll have a firm number before we start.
Roof Washing — Every City We Serve
Select your city for local pricing, neighborhood-specific details, and same-week scheduling.
Frequently Asked Questions About Roof Washing
- Why soft wash instead of pressure washing for roofs?
- High pressure removes the protective granule layer from asphalt shingles, shortening their life and voiding most manufacturer warranties. Soft wash kills the biological growth chemically at low pressure — same result, no damage.
- How long does the moss take to clear after treatment?
- Dead moss typically dries and sheds within 4–8 weeks of treatment. You'll see it lighten and detach progressively. We can come back and blow off stubborn patches if needed.
- Is the solution safe for my landscaping?
- Yes. We pre-wet all plant beds and nearby landscaping before application, use a diluted biodegradable solution, and rinse everything thoroughly afterward. We've treated hundreds of Eastside roofs without landscape damage.
- How often does a roof need to be washed in the Pacific Northwest?
- Most Pacific Northwest homes benefit from a cleaning every 3–5 years, depending on the tree canopy over the roof. Heavy conifer coverage (Douglas fir, cedar) accelerates moss growth and may require more frequent treatment.
- Will roof washing extend my roof's life?
- Yes. Removing biological growth that's actively degrading the shingle surface is one of the highest-ROI maintenance items for a Pacific Northwest home. A well-maintained roof can last 5–10 years longer than a neglected one.
Ready to Book Roof Washing?
Free estimates. Same-week scheduling. Serving the entire Seattle Eastside.