Roof Wash Cost and Process: A 2026 Homeowner Guide
A proper roof wash is a soft wash — low pressure plus a cleaning solution, not a pressure washer aimed at your shingles. With us, it starts at $450 for moss removal and treatment, or $649 for a full roof restoration that includes gutter clearing and a rinse. The exact number depends on your roof's size, pitch, and how much moss and algae has built up. Here's how the process actually works, what drives the price, and how often you really need one.
What Is a Roof Wash, Exactly?
A roof wash is a low-pressure cleaning treatment that kills moss, algae, and lichen at the root using a cleaning solution, then rinses it away — it's not the same thing as blasting your roof with a pressure washer.
The black streaks you're probably seeing are usually Gloeocapsa magma, a blue-green algae that spreads by windborne spores and feeds on the limestone filler in asphalt shingles. It's mostly a cosmetic issue on its own, but the moss that often grows alongside it holds moisture against the shingle and lifts the edges, which is where real damage starts. (Source: Asphalt Roofing Manufacturers Association). A soft wash treats both the algae and the moss without the high-pressure spray that can strip granules and shorten a shingle's life.
How Much Does a Roof Wash Cost?
Here's what we charge for a roof wash, by package:
| Package | Starting price |
|---|---|
| Moss Removal + Powder | $450 |
| Full Roof Restoration | $649 |
Nationally, professional roof cleaning runs about $296 to $625, averaging around $461, or roughly $0.20–$0.70 per square foot depending on the cleaning method. Our pricing sits inside that range, and covers a fully insured soft-wash job with a moss-prevention powder treatment included rather than a bare rinse.
National range sourced from HomeAdvisor's 2026 roof cleaning cost guide.
What Affects the Price of a Roof Wash?
Four things move the number most: roof size, pitch and height, how much moss or algae has built up, and whether you add gutter clearing to the same visit.
- Roof size. Pricing scales with square footage — more roof means more solution, more rinsing, more time.
- Pitch and height. A steep or multi-story roof needs more rope and harness work, which adds to the rate.
- Moss and algae buildup. A roof that's gone three-plus years without treatment takes longer to fully clear than one on a regular schedule.
- Add-ons. Gutter clearing during the same visit (+$50–$150) and moss-prevention zinc strips (+$100–$200) are usually priced separately.
| Add-on service | Typical extra cost |
|---|---|
| Gutter clearing (same visit) | +$50 – $150 |
| Zinc/moss-prevention strips | +$100 – $200 |
| Heavy moss removal (3+ years overdue) | +$75 – $150 |
Soft Wash or Pressure Wash: Which One Does Your Roof Need?
Your roof needs a soft wash, not a pressure wash — pressure washing is for driveways and siding, and using it on shingles is one of the fastest ways to turn a cleaning job into a roof-replacement job.
| Soft Wash | Pressure Wash | |
|---|---|---|
| Method | Low pressure + cleaning solution | High-force water spray |
| Shingle safety | Safe for asphalt, tile, and metal | Can strip granules, void warranty |
| Best for | Roofs (moss, algae, black streaks) | Driveways, siding, decks |
How Often Should You Get a Roof Wash?
Most PNW roofs under regular tree cover need a wash every 2–3 years. Under heavy fir or cedar cover — which, around here, is most of us — plan on closer to every 18 months. Moss doesn't respect a calendar, but it definitely respects shade and rain, and Snohomish County offers it plenty of both.
What Are the Signs Your Roof Needs a Wash?
Green or black streaking on the shingles, visible moss clumps between courses, granules collecting in your gutters, or a roof that just looks "dirty" from the street — any of these mean it's time to book a wash before moss starts lifting shingle edges and creating a path for water underneath.
What Does This Look Like in Snohomish County?
This is what we actually charge across the towns we serve — from Lynnwood to Mill Creek to Bellevue: $450 to start, $649 for the full restoration. Since moss and debris from an untreated roof wash straight down into your gutters anyway, we usually price the two together as a combined visit rather than two separate trips. The most accurate way to know your number is a free estimate. I'll give you a firm price before anything starts, no surprise line items after — see the full breakdown of what's included on our roof cleaning service page, or check every town we cover on the service areas page.
Written by Xzavier
Owner of Xzavier's Gutter and Window Cleaning, licensed and insured in Washington State (license XZAVIGW754N1). I write these from real jobs across Snohomish and North King County — no filler, just what actually costs what. More about us.