Back to Blog Maintenance Should You Pressure Wash Your Roof? (No. Here's Why.)
Mark WhiteJuly 22, 20254 min read Every spring, I see homeowners (and sometimes 'professionals') pressure washing roofs across San Antonio. The results look amazing, for about 6 months. Then the damage shows up: premature granule loss, curling shingles, and leaks at spots where high-pressure water was forced under shingle edges.
Your roof is not your driveway. Here's why the approach matters.
What Pressure Washing Does to Shingles
Standard pressure washers operate at 2,000-3,000+ PSI. Your shingle's granule coating is designed to handle rain (which hits at about 20 mph, or roughly 1-2 PSI of impact) and hail. It is NOT designed to handle 2,000+ PSI at close range.
Pressure washing strips granules like sandblasting, exposes the asphalt layer to UV degradation, forces water under shingle edges and into the deck, can crack or break shingle tabs, and creates channels where future water intrusion occurs.
The roof looks 'clean' because you've literally removed the protective surface layer. You've traded appearance for lifespan.
The Right Way: Soft Washing
Soft washing uses low-pressure application (under 100 PSI, basically a garden hose) of a cleaning solution (typically diluted bleach with a surfactant). The chemistry does the cleaning, not the pressure.
The solution kills algae, mold, and mildew. After rinsing, the roof looks dramatically better without any granule damage. Within weeks, dead algae washes off naturally with rainfall, and the roof continues improving in appearance.
Professional soft washing: $300-$600 for most homes. A fraction of the cost of the premature roof replacement that pressure washing causes.
Schedule a Free Roof Inspection
Not sure about the condition of your roof? We will send a certified inspector to your home at no cost. Same day or next business day availability.
Book Your Free Inspection →Please don't pressure wash your roof. Call Legacy at (210) 272-7272 for a soft wash recommendation.
Got a roofing question? Something keeping you up at night? (Besides that mysterious dripping sound?) Email me personally at mwhite@legacytx.com. I read and answer every single one.
MW Mark White
Owner, Legacy Home Improvements · San Antonio since 1999
Mark has been in the roofing business for over 25 years. He personally inspects homes, works with insurance adjusters, and answers every email at mwhite@legacytx.com.
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