Roof Cleaning That Doesn't Wreck Your Shingles
Manufacturer-approved soft wash plus PNW-specific moss and lichen treatment. Pressure washing strips granules and voids warranties. We do not do that.
- Soft Wash
- Moss Removal
- Algae Streaks
- Maintenance Plans
How a Cleaning Works
Three steps from inspection to clean roof.
Free Inspection
We walk the roof, identify the type of growth (moss, lichen, algae), check shingle integrity, and confirm soft wash is the right approach. Most inspections take 30 to 45 minutes.
Treatment Application
Biocide applied with low-pressure spray. We protect landscaping, mask gutters and downspouts, and avoid runoff to plants. Dieback begins within 48 hours.
Removal and Prevention
After dieback (typically 4 to 6 weeks for heavy moss), we return for gentle removal and zinc strip install. Result: clean roof plus suppression for 3 to 5 years.
What We Clean and Treat
Soft Wash Cleaning
Low-pressure application (under 500 PSI) plus sodium hypochlorite or hydrogen peroxide-based biocide. Removes biological growth without granule loss.
Moss Treatment and Removal
Zinc sulfate or potassium-based moss killer applied to the affected areas. Wait 4 to 6 weeks for full dieback, then gentle removal. No pressure washing required.
Algae Streak Removal
Black streaks on north-facing slopes are Gloeocapsa magma algae feeding on shingle limestone. Soft wash with biocide eliminates it and prevents return.
Lichen Removal
Flat scaly patches that penetrate deeper than moss. Often requires 2 to 3 treatment cycles. We treat patiently rather than scraping aggressively.
Debris Removal
Pine needles, leaves, branches, and seed cones removed from valleys, behind gutters, and around penetrations. Debris holds moisture and accelerates damage.
Zinc Strip Installation
Zinc strips at the ridge release ions that suppress moss and algae regrowth between cleanings. Adds 3 to 5 years between full cleanings.
Annual Maintenance Plans
Schedule recurring cleaning and inspection on an annual or biennial cadence. Catch issues at month 12 instead of year 5.
Call us today or send us a message for a free roof inspection.
We offer financing
We’ve partnered with Wisetack to offer our customers flexible financing options, so you can pay over time rather than all at once. The application takes about a minute to complete, and checking your options does not impact your credit score.
- Finance projects up to $25,000*
- Terms from 3 to 120 months*
- APRs range from 0 to 35.9%*
- No hidden fees or compounding interest
Prequalify today with no impact to your credit and contact us to learn about financing your next project!
*All financing is subject to credit approval. Your terms may vary. Payment options through Wisetack are provided by our lending partners. For example, a $1,200 purchase could cost $104.89 a month for 12 months, based on an 8.9% APR, or $400 a month for 3 months, based on a 0% APR. Offers range from 0-35.9% APR based on creditworthiness. State interest rate caps may apply. No other financing charges or participation fees. See additional terms at https://wisetack.com/faqs. https://www.wisetack.com/faqs..
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Why King County Homeowners Choose Prosperity
5.0 Stars on Google and Facebook
Real reviews from real homeowners. No bots, no buyouts.
Licensed, Bonded, and Insured
Washington State licensure current. Workers comp and liability up to date.
Manufacturer-Approved Methods
Soft wash and biocide compliant with GAF, CertainTeed, and Owens Corning specifications.
Honest Recommendations
Cleaning when cleaning works. Replacement only when the roof is past saving. No upsells.
Local Crews, Not Subcontractors
The technicians on your roof are Prosperity employees trained on PNW-specific moss biology.
Maintenance Plans Available
Annual or biennial recurring service with priority scheduling and discounted pricing for repeat customers.
Industry Excellence
Our Certifications & Affiliations
Master Elite® Contractor
Frequently Asked Questions
Why not pressure wash?
High-pressure water strips the protective granules off asphalt shingles. Granules are what shield the asphalt from UV damage. Once they are gone, the shingle ages 3 to 5 times faster. Pressure washing voids most manufacturer warranties. We do not do it on asphalt.
How often should I have my roof cleaned in King County?
Heavy moss exposure (shaded north slopes, dense tree canopy) often needs every 2 to 3 years. Moderate exposure every 4 to 5 years. Full sun south slopes with zinc strips sometimes go 7 plus years between cleanings. We inspect annually and recommend timing based on actual growth, not a fixed schedule.
Does roof cleaning extend roof life?
Yes when done correctly. Moss physically lifts shingle edges and lets water penetrate. Removing it stops that damage. A roof at year 12 with active moss might fail at year 17. The same roof treated annually often reaches year 24 to 26.
What does soft wash cost?
Typical King County homes run 450 to 950 dollars for a full soft wash with moss treatment, depending on roof size and pitch. Heavier infestations needing return visits cost more. We quote in writing before starting work.
Will the cleaning damage my landscaping?
No. We protect plants and shrubs with tarps, mask gutters and downspouts to control runoff, and use biocides at concentrations safe for landscaping when applied correctly. Damage from properly applied soft wash is rare to nonexistent.
Does roof cleaning void my warranty?
Soft wash done correctly preserves manufacturer warranty. Pressure washing typically voids it. We document the process so you have a record if warranty questions ever come up. Most warranties require regular maintenance to remain in force, so cleaning helps rather than hurts.
Add Five Plus Years to Your PNW Roof
Moss and algae shorten roof life by years. Aggressive cleaning shortens it more. The right answer is soft wash, the right biocide, and a maintenance cadence calibrated for your tree exposure. Free inspection and honest recommendation, whether you book us or not.
Serving Western Washington — Bellevue, Renton, Kirkland, Kent, Sammamish, Redmond, Issaquah, Bothell, and surrounding communities.