Roof moss removal in Shoreline is a $300–$1,200 decision that affects a $15,000+ roof. Yet most homeowners hire the first company that picks up the phone. These seven questions separate the pros from the risks — ask them before anyone climbs your ladder.
1. "Do you pressure wash roofs, or soft wash?"
The right answer: soft wash only — low-pressure application, never a pressure washer on shingles.
Red flag: "We use low pressure" (vague), "it depends on the roof," or any defense of pressure washing asphalt shingles. Pressure washing strips the protective granules off shingles and can void your manufacturer warranty. It looks clean for a month, then the damaged shingles grow moss faster than before. Every shingle manufacturer specifies low-pressure cleaning only.
2. "Is prevention treatment included, or is this scrape-only?"
The right answer: treatment included on every job, with the product named.
Red flag: treatment as an upsell, or "the scraping is enough." Scraping removes visible moss but leaves spores and roots behind — in Shoreline's climate, untreated roofs regrow moss within 1–2 years. A scrape-only quote that looks $150 cheaper is the most expensive option, because you'll pay for the whole job again next year.
3. "Is gutter and downspout cleaning included?"
The right answer: yes, always — dislodged moss goes straight into gutters.
Red flag: "we can add that on" or no mention of gutters at all. A roof cleaning that skips the gutters just moves the problem downhill: blocked downspouts, overflowing water, damaged fascia. If it's a separate line item, ask why a "complete" job doesn't include it.
4. "How do you protect my plants and landscaping?"
The right answer: a specific process — pre-wetting plantings, covering sensitive beds, diverting downspouts, post-job rinse.
Red flag: "our products are safe" with no process described, or visible annoyance at the question. Chemical runoff from careless spraying burns shrubs and kills flower beds — it's one of the most common complaints in contractor reviews. Vague reassurance is not a protection plan.
5. "Is this quote exact, or could the final price change?"
The right answer: the written number is the number you pay; any genuinely unexpected find gets shown to you and approved before extra work happens.
Red flag: "we'll see once we're up there," phone quotes that double on-site, or "this price is only good today" pressure. Wildly varying quotes usually describe different jobs — make every company quote the same scope, then compare.
6. "What happens if the moss comes back?"
The right answer: a specific re-treatment policy with a timeframe — not just "call us."
Red flag: no answer, or "moss always comes back, that's normal" as a shrug. Some regrowth pressure is normal in the PNW, but a company that treats properly should stand behind it with a written re-treatment window. We offer 12 months — read our guarantees.
7. "Are you licensed, bonded, and insured — and can you prove it?"
The right answer: yes, with a Washington contractor license number you can verify, plus liability insurance.
Red flag: hesitation, "we're working on it," or cash-only with no invoice. Anyone on your roof should carry insurance — if a worker falls or a ladder goes through a window, you need to know whose policy responds. Verify the license at the Washington Department of Labor & Industries website.
What a Good Estimate Looks Like
After the questions, the estimate itself should tell you plenty. A professional written estimate names the address, describes the scope (manual removal, soft wash, treatment product, gutter cleaning, cleanup), states one exact price, and lists what's not included. One paragraph and a number scribbled on a business card isn't an estimate — it's a guess.