When we handle roof cleaning for asphalt shingle roofs in Washington, it comes down to three things: protecting your plants and property, cleaning with the right method, and walking the job with you at the end. On asphalt shingle roofs, the method we use is soft wash (no pressure).
How we clean it
Cleaning solution: A diluted sodium hypochlorite solution with surfactant; plants below are pre-wet and rinsed.
What to know about cleaning asphalt shingle roofs
The black streaks on many asphalt roofs are a type of algae, often Gloeocapsa magma, that feeds on the limestone filler in shingles. It is killed with a soft wash solution, not blasted off. The Asphalt Roofing Manufacturers Association advises against pressure washing shingles because it strips the granules that protect them.
Avoid: Pressure washing, which strips granules and shortens the roof's life, and walking on wet, slick shingles.
How often: Every 3-5 years, or when streaks return.
Is it time for roof cleaning for asphalt shingle roofs?
- Black or dark streaks running down the roof
- Green moss or lichen spots, often on the north side
- Roof looks older than it is
- Moss lifting the edges of shingles
- A home inspector or insurer has noted roof growth
What causes the dirt and stains
- Roof algae (often Gloeocapsa magma) spread by wind
- Shade from trees and the north-facing side staying damp
- Debris piles in valleys that hold moisture
- Moss and lichen that root into the roof surface
What you can do yourself
- Keep valleys and gutters clear of leaves and pine needles
- Trim branches to let in sun and air
- Consider zinc or copper strips near the ridge to slow regrowth
- Look from the ground with binoculars instead of climbing on the roof
Not sure what you're looking at? The free stain identifier and safe pressure guide explain each stain and surface.
Common mistakes to avoid
- Pressure washing strips granules and can void a shingle warranty
- Falls from a slippery, wet roof
- Chemical runoff that burns plants below
- Water forced under shingles and flashing
What happens on the day
- Check the roof type, pitch and condition from the ground and ladder
- Pre-wet and protect plants and cover sensitive areas
- Apply a soft wash solution suited to the roofing material
- Let it work, then rinse gently or let rain finish the job as recommended
- Rinse gutters, downspouts and plants and check the results
How much does roof cleaning for asphalt shingle roofs cost?
What moves the price:
- Size: square footage of siding, roof or flatwork
- Condition: heavy growth, old stains and peeling finishes take longer
- Access: number of stories, roof pitch, slopes and how close we can park
- Add-ons: sealing, gutter brightening and other services done in the same trip
These are typical U.S. ranges, not a quote. You get an exact price before any work starts. For a quick estimate, try the pressure washing cost calculator.
Other services for asphalt shingle roofs
Local roof cleaning for asphalt shingle roofs for Washington
Moss is the number one roof cleaning job in Washington. It holds water against shingles and can lift their edges, so it should be treated with a soft wash and removed gently, never pressure washed off.
Near the coast, salt air leaves a film on siding, windows, screens and railings that dulls finishes and speeds up corrosion on metal. Regular rinsing and washing help protect them.
We cover 310 cities and towns across Washington. Find roof cleaning for asphalt shingle roofs in your city:
Roof Cleaning for Asphalt Shingle Roofs: frequently asked questions
How much does roof cleaning for asphalt shingle roofs cost in Washington?
Roof Cleaning for Asphalt Shingle Roofs typically costs $400-$1,000 for a typical single-story or two-story home, and usually takes 2-4 hours. The exact price depends on the size and condition, and you get it before any work starts. Call (555) 010-0000 for a free quote.
Do you use high pressure for roof cleaning for asphalt shingle roofs?
For asphalt shingle roofs: no pressure washing; the solution is applied at very low pressure and rinsed gently. What we avoid: pressure washing, which strips granules and shortens the roof's life, and walking on wet, slick shingles. The cleaning solution does most of the work, followed by a gentle rinse.
Is roof cleaning for asphalt shingle roofs safe for my plants and pets?
We pre-wet plants and lawns, keep cleaning solutions diluted to what the surface needs, and rinse landscaping again when we finish. Keep pets and children inside until surfaces are rinsed and dry.
How often should I schedule roof cleaning for asphalt shingle roofs?
Every 3-5 years, or when streaks return. Shade, nearby trees, humidity and heavy traffic mean more frequent cleaning; sunny, dry spots can go longer. Our free cleaning frequency tool gives a recommendation for your climate.
What if it rains on the day?
Light rain doesn't stop most washing, but heavy rain, high wind, lightning and freezing temperatures do. If the weather isn't right, we reschedule at no charge. Our work is backed by a satisfaction guarantee.