Soft wash only — never pressure. Concrete S-tile roofs across Willow Glen, Cambrian, Almaden Valley, and Evergreen. Algae, moss, and lichen removed without cracking tile or stripping coating. Same-day estimates. No travel fees — we're based in San Jose.
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San Jose has more concrete S-tile roofs than any other city in the South Bay. The tracts built through the 1970s, 80s, and early 90s in Cambrian, Almaden Valley, Blossom Valley, and Evergreen put S-tile on tens of thousands of homes. That tile was the right choice — durable, low-maintenance, long-lasting. The problem is the marine layer that funnels through the Santa Clara Valley from the Bay each morning, settling into the south and west-facing neighborhoods and keeping north-facing roof planes damp well into late morning. In a shaded Willow Glen yard or an Almaden Valley lot backed up to the foothills, that moisture never fully dries out — and moss moves in.
Concrete S-tile is porous. It absorbs moisture and holds it longer than clay, metal, or composite. Once moss and algae establish roots in porous tile, surface washing just removes the visible layer — spores are still embedded and regrowth comes back in months. Our soft-wash process uses a biodegradable algaecide that penetrates the tile and kills biological growth at the root. The streaking stays gone because the organism is gone, not just scrubbed off the surface.
Mature oak, pine, and liquid amber canopy in Willow Glen, Almaden, and the Cambrian foothills creates persistent shade on north and west-facing roof planes. Shade keeps tile damp, damp tile grows algae, and algae feeds moss. Homes on lots with significant tree coverage typically need cleaning every 3 to 4 years rather than every 5 — the canopy overrides some of the algaecide treatment window. We account for this when we scope a job in person.
Pressure washing S-tile (anything above 500 PSI) cracks the curved surface and strips the protective glaze that seals the concrete from moisture absorption. Every roof we clean in San Jose uses under 500 PSI. The chemistry does the work. Tile comes out clean, intact, and protected — not blasted into a surface that will re-grow algae twice as fast as before.
Ready for a free San Jose S-tile roof estimate? We scope every roof in person — no guessing, no surprise charges on the day of the job.
We walk the roof, identify moss coverage and growth density, note solar panels, skylights, or HVAC equipment, and check downslope landscaping. No two San Jose roofs are identical — the assessment drives the approach.
Before solution goes up, we saturate all surrounding plantings and cover anything sensitive. Our biodegradable surfactant is plant-safe at diluted application, but we pre-wet on every job as a standard precaution.
Algaecide and surfactant applied at under 500 PSI. Dwell time is 10 to 20 minutes depending on growth density and tile porosity. The chemistry kills the organism — the pressure just delivers the solution.
Gentle rinse removes loosened biological material and residual solution. Dead moss sloughs off cleanly without cracking the S-tile profile. We direct the rinse to prevent re-depositing debris on cleaned sections below.
Two options after the roof is clean. Zinc powder solution — zinc sulfate powder mixed into water and sprayed across the entire tile surface. Zinc ions absorb into porous concrete and release slowly with each rain event, disrupting photosynthesis and enzyme function in algae, rupturing moss cell membranes, and preventing lichen from anchoring. Extends the clean to 3–5 years. Zinc strips — metal strips fastened along the ridge line. Rain passing over the strips continuously leaches zinc ions down the roof for the life of the strip, up to 10–20 years of passive protection. Both are add-ons scoped at the time of the estimate.
Gutter flushing is included with every roof wash — not an add-on. Debris loosened from the roof lands in the gutters, so we flush them out before we leave. Downspouts cleared, gutters flowing. One visit, one setup, done.
Gutter flush is included. Want to add zinc treatment? Most San Jose homeowners add zinc when they book — powder solution or strips, scoped in person. Call or text. Call or text and we'll cover everything.
San Jose concrete S-tile roof — algae streaking and moss growth on north-facing planes. Soft washed with algaecide and post-treated to prevent regrowth.
Results like these on your San Jose S-tile roof. Call or text for a free soft-wash estimate — same-day response.
Straight answers for San Jose homeowners. Don't see yours? Call or text (408) 598-1857 — happy to walk you through anything.
No — never. Pressure washing S-tile cracks the curved surface and strips the protective coating that seals porous concrete from moisture. We soft wash every San Jose roof at under 500 PSI using a biodegradable algaecide that kills biological growth at the root, not just at the surface.
All of San Jose — Willow Glen, Cambrian Park, Almaden Valley, Blossom Valley, Evergreen, Silver Creek, Berryessa, Rose Garden, and downtown-adjacent neighborhoods. We're based in San Jose so there are no travel fees anywhere in the city.
Morning marine layer funnels through the Santa Clara Valley from the Bay and settles into south and west San Jose neighborhoods. North-facing S-tile planes stay damp well into late morning — ideal conditions for Gloeocapsa Magma and common roof mosses. Mature tree canopy in Willow Glen, Almaden, and Cambrian adds shade that keeps those planes wet even longer. Concrete tile is porous and absorbs that moisture — left untreated, you'll see black streaking in 2 to 3 years and active moss within 5.
Soft washing a tile roof correctly is a 1 to 2 day process depending on roof size and growth density. Biological growth is a living organism embedded in porous tile — the chemistry needs dwell time to penetrate and kill it at the root. Homeowners who rush this typically see regrowth within months. We do it right the first time.
Most San Jose roofs we treat stay visibly clean for 3 to 5 years after a soft wash alone. With zinc strip installation, that window extends to 5 to 7 years on most roofs. Results vary by pitch, tree canopy, and orientation — north-facing planes under Almaden or Willow Glen canopy re-grow faster than exposed south-facing planes in Evergreen or Silver Creek.
We offer two add-ons after the soft wash. Zinc powder solution: zinc sulfate powder dissolved in water and sprayed across the cleaned tile surface. Zinc ions absorb into the porous concrete and leach out slowly with rain, making the surface hostile to algae, moss, and lichen. Protection typically lasts 3–5 years. Zinc strips: metal strips fastened along the ridge line. Every rain event carries zinc ions down the full length of the roof — passive, continuous, maintenance-free protection that lasts 10–20 years without retreatment. Strips are the longer-term investment; powder solution is the lower upfront cost. Both are optional add-ons scoped at the time of the estimate.
Yes. Bull Run Exterior Wash LLC is fully licensed and carries general liability insurance. Roof cleaning involves working at height — insurance is not optional and we carry it on every job. Your property is protected.
Under 500 PSI on every roof — always. Standard pressure washers run 2,000 to 4,000 PSI. That level of pressure cracks the surface of concrete S-tile, strips the glaze that seals the tile from moisture, and forces water under the tile into the underlayment. The cleaning on our jobs is done by the chemistry — a biodegradable algaecide that kills biological growth at the root. The water pressure is just the delivery mechanism, not the cleaning agent.
Not exactly. Spanish tile (clay barrel tile) is fired clay. Concrete S-tile mimics the same curved profile but is made from portland cement and aggregate. Concrete tile is more common in South Bay tract homes built in the 1970s through 1990s and is more porous than clay — it absorbs more moisture and grows algae faster. The soft-wash approach is similar but concentration and dwell time are adjusted for the more porous concrete surface.
No. Soft washing at under 500 PSI does not crack or chip concrete S-tile. High-pressure washing (2000+ PSI) is what damages tile. Our process uses chemistry, not force — the algaecide breaks down the biological growth and the low-pressure rinse removes it. The tile surface stays intact.
Gutter flushing is included with every roof wash — it is not a separate charge. Debris loosened from the roof lands in the gutters, so we flush them out before we leave. Downspouts cleared, gutters flowing. One visit, one invoice.
Yes. We clean solar panels and the surrounding tile in one visit. Algae and debris on tiles around panels can re-deposit on panel glass — cleaning both at once prevents that. We use deionized water on panel glass to avoid mineral spotting.
We're based in San Jose — same-day estimates are common and scheduling typically runs 3 to 10 days out depending on season. September through May is our busiest window. Book early for fall slots. Call or text (408) 598-1857.
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