Pressure washing strips the protective granules off asphalt shingles, voids your warranty, and shortens roof life by 5-10 years. Here's why so many Tampa Bay homeowners get talked into it, and what actually works for algae and stains.
By Tyler Wisdom | Roofing | 2026-03-04 | 7 min read
roof cleaning · pressure washing · roof algae · soft wash · tampa roofing · florida roof maintenance
Spring rolls into Tampa Bay and the pressure washing crews come out in force. Driveways, sidewalks, fences, pool decks — and roofs. We get calls every week from homeowners whose 'roof cleaner' damaged their shingles with a pressure washer, or who are about to hire one and want to know if it's safe.
Short answer: pressure washing your asphalt shingle roof is one of the worst things you can do to it. Here's why, what it actually does to your shingles, what voids your warranty, and what the safe alternatives are for cleaning a Florida roof.
Asphalt shingles are designed with a layer of mineral granules embedded in the asphalt mat. Those granules are not decorative — they protect the asphalt from UV degradation, weather, and physical wear. They're the single most important component of your roof's lifespan.
A residential pressure washer outputs water at 2,000-4,000 PSI. The bond between granules and asphalt is rated for water impact at no more than 100 PSI. The math is brutal: pressure washing literally blasts the protective layer off your shingles. The damage isn't always visible immediately — you'll see clean shingles and assume it worked — but the accelerated UV degradation begins the day the granules come off.
All three major shingle manufacturers (GAF, Owens Corning, CertainTeed) explicitly exclude pressure washing damage from warranty coverage. GAF's published guidance states: 'Pressure washing... will damage shingles and void the warranty.' Owens Corning and CertainTeed have identical language.
If your shingles are pressure washed and you later submit a warranty claim for accelerated aging, granule loss, or wind damage, the manufacturer's response will be to deny — and they'll point to telltale signs of pressure washing (uniform granule loss on accessible slopes, blast patterns near edges, lifted shingles in specific patterns) as evidence.
Some 'roof cleaners' in Tampa Bay use pressure washers at lower PSI (1,000-1,500) and call it 'low pressure.' This still damages shingles. The only safe pressure for asphalt shingle cleaning is essentially garden-hose pressure (60-80 PSI). If their equipment makes a hissing/blasting sound, it's too much pressure for your roof.
Concrete or clay tile roofs can handle moderate pressure washing more safely than asphalt shingles — but it's still risky. The tiles themselves can be cleaned at 1,500-2,000 PSI, but the underlayment is exposed at every grout line, and high-pressure water forced down those gaps can cause underlayment failure, leaks, and tile cracking from impact. Tile roof cleaning should still default to soft wash, not pressure.
Standing seam metal roofs are the most pressure-tolerant of any common Tampa Bay roof type — but even here, pressure can damage the factory paint finish (Kynar 500, PVDF), force water under panel seams, and chip exposed fasteners. Manufacturer guidance for most painted metal roofs caps cleaning pressure at 1,200 PSI with a wide-angle tip. Soft wash is still the recommended approach.
The industry-standard method for cleaning asphalt shingle roofs is called 'soft wash.' It uses low pressure (under 100 PSI) combined with a sodium hypochlorite (bleach) solution to chemically kill algae, mildew, and bacterial colonies. The chemistry does the work — not the pressure.
Properly performed soft wash:
Soft wash kills 100% of visible algae, mildew, and lichen on contact, and prevents regrowth for 3-5 years. It's the only method that's both effective and safe for asphalt shingles.
Not all 'soft wash' crews actually use safe pressure. Before hiring, ask these specific questions:
If you want to clean your own roof and you're comfortable on a ladder (not walking the roof itself — never walk a wet roof), DIY soft wash is doable. The recipe most professionals use:
Tampa Bay homeowners should plan soft wash treatments every 3-5 years. After cleaning, ask any roofer doing your replacement about installing zinc or copper strips at the ridge — they release ions when it rains that prevent algae regrowth for 15-20 years.
If your roof has visible algae plus other issues — granule loss, brittle shingles, exposed nails, lifting at edges, soft spots in decking — cleaning is putting lipstick on a bigger problem. Get a free inspection from a licensed roofing contractor first. A 20-year-old algae-stained roof may need replacement, not cleaning.
Don't pressure wash your asphalt shingle roof. Don't let anyone else pressure wash it. Use soft wash (chemical, low-pressure) instead. It's the only method that's both effective and safe — and it doesn't void your warranty.
Gladiator Exteriors doesn't do roof cleaning ourselves, but we'll happily inspect your roof's condition (free) and refer you to vetted soft-wash specialists in Tampa Bay. If your roof is past cleaning and into replacement territory, we can quote that too. Call (813) 419-2656. Veteran-owned, licensed Florida contractor CCC1337377.
Call (813) 419-2656 for your free estimate.