It's a fair question, and a smart one to ask before anyone touches your roof: will cleaning my roof void the shingle warranty? For Central Ohio homeowners watching black algae streaks creep across their shingles, the worry is real — a new roof is one of the most expensive things you'll buy for your home.
The short answer: roof soft washing, done correctly at low pressure, does not void a typical asphalt-shingle warranty. Roof pressure washing — high-pressure power washing — absolutely can. The method matters, and that distinction is the whole point of this guide.
What your shingle warranty actually covers
Most asphalt-shingle warranties cover manufacturing defects — problems with how the shingle was made, not how it's maintained over time. They generally do not cover damage caused by improper maintenance, abuse, or work done outside the manufacturer's guidelines. Cleaning itself usually isn't a covered event either way — but cleaning the wrong way can be treated as damage that reduces or voids your coverage.
In other words: gentle, correct cleaning keeps you safely inside the lines. Aggressive cleaning that strips granules or drives water under the shingles is exactly the kind of damage a manufacturer can point to when denying a claim. Terms vary by brand, so it's always worth reading your specific warranty.
Why ARMA recommends soft washing
The Asphalt Roofing Manufacturers Association (ARMA) — the trade body for the companies that actually make shingles — addresses algae and moss removal directly. Its guidance is to apply a diluted cleaning solution at low pressure and rinse gently. It specifically warns against power washing asphalt shingles, because high pressure removes the granules that protect the shingle from UV and weather.
Soft washing follows that guidance precisely. We use roof-safe, properly diluted chemistry to kill the algae (the black streaks you see are a hardy cyanobacteria, Gloeocapsa magma) and moss at the root, then rinse at low pressure. No blasting, no granule loss, no water forced under the shingles.
How high pressure puts both your roof and your coverage at risk
- Granule loss — the mineral granules are your shingle's sunscreen and armor. Stripping them shortens roof life and is visible, documentable damage.
- Water intrusion — high pressure can drive water up and under shingles, leading to leaks, rot, and mold in the deck below.
- Lifted or broken shingles — pressure can crack aging shingles or break the sealant tabs that keep them down in Ohio's wind.
- A voided claim — if a manufacturer's inspector finds pressure-washing damage, that can be grounds to deny warranty coverage.
What soft washing does instead
A roof soft wash treats the cause, not just the appearance. The cleaning solution kills the algae and moss so it doesn't simply grow back in a few months, and the low-pressure rinse removes it without disturbing the granules. Results typically last 2–4 years in Central Ohio depending on shade and tree cover — and your warranty stays intact. Learn more on our roof soft washing service page.
Protecting your warranty: what to ask a roof cleaner
- "What pressure will you use on my shingles?" The right answer is low pressure / soft wash — never power washing.
- "What cleaning solution do you use, and is it diluted to roof-safe levels?" Roof-safe, properly diluted chemistry is the ARMA-aligned approach.
- "Are you insured, and can I see proof?" A professional carries liability insurance and will show it on request before starting work.
- Keep your records. Save your warranty documents and any cleaning receipts; documentation of proper, low-pressure maintenance is exactly what protects a future claim.
The bottom line for Central Ohio homeowners
You don't have to choose between a clean roof and a valid warranty. Soft washing — the method ARMA points to — removes the algae and moss safely and keeps your coverage intact. The thing to avoid is letting anyone aim a high-pressure wand at your shingles. For related reading, see soft washing vs pressure washing and the best time of year to wash your home in Central Ohio.
Want a roof cleaned the safe, warranty-friendly way? See our roof soft washing service for how we clean shingles at low pressure, then get a free, no-obligation estimate and we'll walk you through exactly what we'll use on your roof.