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Green Stains on Stucco? Soft-Wash Algae, Don't Blast It

Updated 2026-09-03 · Sources verified 2026-07-20

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Short answer: no permit. Washing a house is maintenance, not construction — there is nothing here for Orange County's permit guide to permit. The pressures and chemicals are where the real risk lives, not the paperwork. The full answer and its source are below, with the code requirements and mistakes that trip up Orlando homeowners.

The permit answer

No permit. Washing a house is maintenance, not construction — there is nothing here for Orange County's permit guide to permit. The pressures and chemicals are where the real risk lives, not the paperwork.
Source: https://www.orangecountyfl.net/PermitsLicenses/DoINeedaPermit.aspx

Orange County and the City of Orlando run separate permit offices with separate portals — and your mailing address alone doesn't tell you which one covers your home. Check which permit office covers your address →

Key facts before you start

Tip colors are spec, not preference (SIMPSON manual): red 0-deg is for unpainted metal/concrete only and will gouge wood, siding, and stucco; white 40-deg is the ONLY tip for painted stucco, vinyl, and painted siding; black low-pressure tip for soap. Keep the nozzle ~4 ft from siding.
PSI by surface: concrete driveways/pool decks take 2,500-3,000+ PSI (use a surface-cleaner attachment for even results); vinyl siding max 2,400 PSI with a 40-deg tip (Georgia-Pacific spec, 1,500 min); stucco needs a wide flat-jet at 8-20 in distance and a tap-test first for loose/drummy render (Karcher) -- never pressure-wash window screens or old single-pane glazing.
Florida green/black staining is live mildew/algae, not dirt: kill it with a sodium-hypochlorite soft-wash solution (GP's mildew mix: 1 qt 5% sodium hypochlorite + 2/3 cup TSP + 1/3 cup detergent in 3 qt water) with dwell time, then low-pressure rinse; raw pressure alone smears spores, regrows in weeks, and etches stucco.
Never spray UPWARD or into openings: water driven up behind siding laps, into soffit vents, window seals, or the stucco weep screed at the foundation gets trapped and rots the wall -- the weep screed exists to drain water OUT (FBC Residential R703.7.2.1); hold the wand at eye level, work top-down.
Never use a pressure washer from a ladder -- the spray gun's reactive kickback force causes falls (verbatim SIMPSON manual warning); use an extension wand or soft-wash from the ground for second-story work.
Spray at electrical receptacles, switches, fixtures, or anything on a circuit can cause fatal shock -- direct spray away and never clean electrically operated devices even when unplugged (SIMPSON DANGER notice); plug electric washers only into GFCI-protected outlets, and treat any skin hit by the jet as an injection injury needing medical care (CDC).

What it costs

DIY: $45–$250 per day to rent a pressure washer, depending on size and gas vs. electric
Hiring it out: $170–$360 to power wash a house; $100–$260 for a deck or driveway
Driveways with heavy mold/mildew that need hand-scrubbing with bleach solution run $0.40–$1.25 per sq ft.
Published national figures (HomeGuide, checked Aug 2026): https://homeguide.com/costs/pressure-washing-prices. Prices move — the free planner pulls current retail prices for your exact repair.

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Frequently asked questions

Do I need a permit for pressure washing in Orange County, FL?

No permit. Washing a house is maintenance, not construction — there is nothing here for Orange County's permit guide to permit. The pressures and chemicals are where the real risk lives, not the paperwork.

What's the biggest safety risk to know about before pressure washing?

Never use a pressure washer from a ladder -- the spray gun's reactive kickback force causes falls (verbatim SIMPSON manual warning); use an extension wand or soft-wash from the ground for second-story work.

Are there specific building-code requirements for pressure washing?

Never spray UPWARD or into openings: water driven up behind siding laps, into soffit vents, window seals, or the stucco weep screed at the foundation gets trapped and rots the wall -- the weep screed exists to drain water OUT (FBC Residential R703.7.2.1); hold the wand at eye level, work top-down.

What does pressure washing cost?

DIY: $45–$250 per day to rent a pressure washer, depending on size and gas vs. electric Hiring it out: $170–$360 to power wash a house; $100–$260 for a deck or driveway Driveways with heavy mold/mildew that need hand-scrubbing with bleach solution run $0.40–$1.25 per sq ft. Published national figures (HomeGuide, checked Aug 2026) — local prices vary, and the free DIYrr planner pulls current retail prices for your exact repair.

Related repairs

Sources

https://simpsoncleaning.com/wp-content/uploads/7110453-3.pdf
https://www.gpvinylsiding.com/support/care-and-maintenance/
https://www.kaercher.com/int/professional/know-how/cleaning-plaster-facade.html
https://www.cdc.gov/natural-disasters/safety/pressure-washer-safety.html
https://codes.iccsafe.org/s/FLRC2020P1/chapter-7-wall-covering/FLRC2020P1-Pt03-Ch07-SecR703.7.2
https://www.generacpowerproducts.com/pages/content/articles/article-pressure-washer-nozzles-demystified

This guide is general informational content, not professional or legal advice. Codes and county rules change — confirm permit requirements with your local building department, and use a licensed professional for electrical, gas, structural, or main-line plumbing work.

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