Not every roof washing company uses the same method or carries the same insurance. Here's what to check before you hire one — plus real Snohomish County pricing.
Most roof washing companies fall into one of two camps: a truck with a pressure washer and a magnet sign, or a licensed, insured crew using a low-pressure soft wash built for shingles. The difference matters more than the price tag — the wrong method can strip granules and shorten your roof's life, and the wrong hire can leave you liable if someone gets hurt on a ladder over your driveway. Here's what actually separates a company worth hiring from one to skip, what a fair price looks like, and what this looks like for homeowners here in Snohomish County.
What Does a Roof Washing Company Actually Do?
A roof washing company removes moss, algae, lichen, and the black streaking that builds up on shingles, using either a low-pressure "soft wash" solution or, less often and less safely, a pressure washer. The good ones also treat for regrowth and clear debris from valleys and gutters while they're up there.
Most of that black streaking is Gloeocapsa magma, a blue-green algae that spreads by windborne spores and feeds on the limestone filler in asphalt shingles. Left alone, the moss that tends to grow alongside it holds moisture against the shingle and lifts the edges — that's where a cosmetic problem turns into a leak. (Source: Asphalt Roofing Manufacturers Association)
Soft Wash or Pressure Wash: Which Method Should They Use?
Your roof needs a soft wash, not a pressure wash — high-pressure spray is built for driveways and siding, and pointing it at asphalt shingles is one of the fastest ways to turn a cleaning job into a roof-replacement job. If a company's first pitch is a pressure washer, that tells you most of what you need to know before you even ask about price.
- Method — Soft wash uses low pressure plus a cleaning solution. Pressure wash blasts water at high force.
- Shingle safety — Soft wash is safe for asphalt, tile, and metal roofs. Pressure wash can strip granules and void your shingle warranty.
- Kills moss at the root — Soft wash does. Pressure wash usually just knocks the visible growth loose and leaves the roots behind.
- Best use — Soft wash for roofs. Pressure wash for driveways, siding, and decks.
Most major shingle manufacturers, including GAF, specifically recommend low-pressure cleaning methods over pressure washing, for exactly this reason.
What Should Roof Washing Companies Charge?
A fair price for professional roof washing runs about $296 to $625 nationally, averaging around $461, or roughly $0.20–$0.70 per square foot depending on method and roof condition. Steeper, larger, or heavily-mossed roofs land at the top of that range.
- National average, all methods: $296 – $625
- Xzavier's Moss Removal + Powder: $450
- Xzavier's Full Roof Restoration: $649
National figures sourced from HomeAdvisor's 2026 roof cleaning cost guide. Our own pricing sits inside that national range and includes a fully insured soft-wash job — the restoration tier adds gutter clearing and a moss-prevention powder treatment rather than a bare rinse. A quote that comes in dramatically below $296 is usually a pressure-wash-only job, not a soft wash, so ask which method is included before you compare numbers.
What Should You Look for in a Roof Washing Company?
Look for four things before you sign anything: a current Washington State contractor registration, active liability insurance, a soft-wash-first method, and a written estimate that names the price before work starts.
- WA contractor registration number — confirms they're legally allowed to operate. You can verify any number yourself through Labor & Industries' public lookup in under a minute.
- Liability insurance — if a ladder scratches your siding or someone's hurt on your property, this is what covers it, not your homeowner's policy.
- Soft wash as the default method — the single biggest predictor of whether your shingles survive the job.
- Written estimate before work starts — protects you from a number that grows once the crew is already on your roof.
Nobody grows up dreaming of spending a Tuesday morning on a wet, mossy roof — but a company that still takes the licensing and safety seriously anyway is the one you want up there, not just the cheapest bid.
What Are Red Flags to Avoid?
Walk away from any company that can't produce a registration number or proof of insurance on request, that pressure-washes as a default rather than an exception, that quotes a firm price sight-unseen over the phone with no photos or walkthrough, or that asks for full payment upfront before any work is done. A legitimate company answers all four of those without hesitation.
Do Roof Washing Companies Offer Guarantees?
Some do, though it varies by company. What's more common and more useful is a moss-prevention add-on — usually zinc or copper strips installed along the ridge — that slows regrowth between washes, since no soft wash permanently stops moss from coming back on a shaded roof.
What Should You Expect the Day of the Wash?
A soft wash crew should walk the roof first, note any loose or lifted shingles before touching anything, and cover nearby plants and landscaping since the cleaning solution isn't meant for your flower beds. From there, most homes take 1–3 hours from setup to final rinse, depending on roof size, pitch, and how much moss has built up.
We tarp gutters and downspouts before we start so loosened moss doesn't just clog them on the way down, apply the solution, let it sit and work, then rinse from the top down. A crew that skips the walk-through and heads straight to spraying is usually rushing the job, not respecting your roof.
Hiring a Roof Washing Company in Snohomish County
Under the fir and cedar cover most of us live under here, moss isn't a maybe — it's a matter of when, not if. We wash roofs across the towns we serve, from Everett to Lynnwood to Mill Creek, and we price it the same way described above: $450 to start, $649 for the full restoration, no surprise line items after the crew shows up. Since moss and grit from an untreated roof mostly ends up in your gutters anyway, we usually bundle the two into one visit instead of sending a truck twice.
If you want an exact number instead of a range, a free estimate takes a few minutes and gets you a firm price before anything starts. You can also check every neighborhood we cover on the service areas page.