Clean stucco with low pressure and the right cleaning solution, not a strong pressure washer. Stucco is porous, and high pressure can erode the finish and push water into cracks. Stucco maker Sto Corp. says not to exceed 500 psi. Test a small area first, and repair cracks or failed sealant before washing.
What's growing on your stucco
Stucco is a porous, cement-based finish, so it holds moisture, and in Florida it spends a lot of time damp. PROSOCO, a maker of masonry cleaning products, says algae, mold, and mildew often show up where shade and moisture persist and shouldn't be treated as ordinary dirt. Other common stains include dirt and dust held in the texture, white mineral marks from sprinkler spray and runoff, and a dull gray or black film from soot and airborne particles.
Why high pressure is risky on stucco
The finish is a thin, textured layer. Sto Corp., a stucco manufacturer, warns in its maintenance guide not to exceed 500 psi, because higher pressure can destroy the surface integrity of the finish. PROSOCO also says low-pressure water is usually the safer direction for stucco, and that excessive pressure can erode the texture or force water into cracks.
Many pressure washers are rated far above 500 psi. Water forced into cracks can end up behind the finish, where you can't see it, which is why we don't point a pressure washer at a home's exterior.
What a soft wash does differently
A soft wash applies a cleaning solution at low pressure, gives it time to work on the algae and mildew, and then rinses gently. The solution does the cleaning instead of force. Rinsing thoroughly matters too: PROSOCO notes that leftover cleaner and loosened soil can dry in the texture and leave streaks.
Shine Otter's home soft wash uses a specially mixed, biodegradable cleaning solution and low water pressure. An annual whole-home soft wash is included in our Pro, Premier, and Ultimate VIP Home Care Memberships.
Look before you wash: cracks and moisture
Walk the walls first. PROSOCO advises pausing cleaning when damage could let water get behind the finish, such as cracks, loose areas, open joints, failed sealant, or damaged paint. It also says recurring moisture, cracks, or failed sealant should be corrected rather than washed over again and again.
Cleaning is not a repair. If a wall stays wet, the stains keep coming back, or you see cracks that could let water in, call a licensed stucco or painting contractor to find the cause. After a storm, check for new cracks before you wash.
If your stucco is painted
Painted stucco needs extra caution, PROSOCO notes, because the cleaner has to be compatible with the paint as well as the stucco. Test a small, out-of-the-way spot first. Peeling or flaking paint can come off under water pressure, so look closely before you start.
Keeping stucco clean longer
- Re-aim sprinklers so they don't hit the walls. Mineral-heavy or well water can leave white or rust-colored marks.
- Keep gutters and downspouts working so roof runoff doesn't splash or run down the walls. See how often to clean gutters in Florida.
- Trim plants back from the walls so air can circulate and the surface can dry.
- Fix leaks and cracks promptly so moisture isn't feeding the stains.
- Clean before growth takes hold. Light algae and mildew come off more easily than heavy buildup, and many homeowners in humid areas clean every year or two.
Not sure what your walls need? Call or text (425) 977-5156 and we'll tell you what we'd recommend.
Frequently asked questions
Can I pressure wash stucco?
Manufacturers advise against high pressure. Sto Corp. says not to exceed 500 psi, and PROSOCO says low-pressure water is usually the safer direction. Many pressure washers are rated well above that, which is one reason we use a low-pressure soft wash on stucco.
How often should stucco be cleaned in Florida?
It depends on shade, moisture, and sprinkler overspray. Many homeowners in humid areas clean stucco every year or two, and damp, shaded walls may need it sooner.
Why does my stucco turn green or black?
Usually algae, mold, or mildew, which grow on walls that stay damp and shaded and near sprinklers and runoff. Rust-colored or white marks more often point to well water or minerals from sprinklers than to growth.
Sources & further reading
- PROSOCO: How to Clean Stucco Safely Without Damaging the Surface
- Sto Corp.: Stucco Repair and Maintenance Guide
About Shine Otter
Shine Otter is a family owned and operated exterior cleaning company serving Southwest Florida, from Englewood and Venice to Cape Coral and Fort Myers. We handle window cleaning, roof and gutter cleaning, soft washing, driveway and patio cleaning, window screen cleaning, storm debris cleanup, and solar panel cleaning. Call or text (425) 977-5156 for a free quote. Meet the owners.