Yes, you can clean a stucco house in Miami, but the safest way is a low-pressure soft wash, not a hard blast from a pressure washer. Most homes here are concrete block with a stucco finish, and stucco is a porous cement coating. Too much pressure can strip paint, gouge the surface and push water into hairline cracks, while a cleaning solution at gentle pressure kills the algae and mildew that cause most of the staining.
Why stucco is easy to damage
Stucco is a layer of cement plaster over block. It is hard, but it is also absorbent and often cracked in small ways nobody has noticed. Paint on top of it is usually only a thin film. A narrow, powerful jet can do three kinds of harm:
- Surface damage. Pitting, etched lines and bare patches where the paint and the top of the finish were blown off.
- Water intrusion. Water driven into cracks, around windows and behind trim can end up inside the wall, where it stays damp for a long time in this climate.
- Uneven results. Stripes and a patchy, "tiger" look where the nozzle passed too close.
Cleaning companies tend to describe the safe pressure limit differently, and many of those numbers come from people selling the service. The consistent advice is to use as little pressure as the job allows and to rely on the cleaning solution to do the work. If you are weighing the methods in general, our comparison of soft wash and pressure wash explains the difference.
Know what you have before anyone washes it
Not everything that looks like stucco is the same material. The wall type decides how gentle the cleaning has to be.
| Wall finish | What it is | Cleaning approach |
|---|---|---|
| Traditional cement stucco over block | Cement plaster, painted or integrally colored | Soft wash; low-pressure rinse |
| Textured or dash finish | Rough surface that traps dirt in the texture | Soft wash plus gentle brushing if needed |
| EIFS ("synthetic stucco") | Foam board with a thin coating | Very gentle; check the manufacturer's cleaning guidance first |
| Cracked or patched stucco | Older wall with visible repairs | Inspect first; hand wash or soft wash only |
EIFS deserves extra caution. Manufacturers of these systems publish their own cleaning limits, and several restrict high-pressure washing. If you are not sure which type you have, ask whoever built or inspected the house, or ask a contractor to identify it before any water is sprayed.
What the stains on stucco usually are
Dark streaks under eaves and on the shady side are almost always algae, mildew or cyanobacteria. Our guide to mold, mildew and algae on exterior surfaces covers how to recognize them. Other common stains look different:
- Orange or brown streaks are often rust from irrigation water or from metal fixtures. Algae treatments do not remove them.
- White, powdery deposits are usually efflorescence, which means minerals are moving through the wall with moisture. Cleaning the surface does not fix the moisture source.
- Dark lines running down from a crack can mean water is getting in at that spot.
- Grime at the base of the wall is often splash-back from sprinklers, downspouts or soil.
How a gentle stucco wash works
- Walk the walls first. Note cracks, loose sealant, damaged screens and gaps around windows and doors.
- Protect what should not get wet. Close windows and doors, cover outlets and light fixtures, and move furniture and cars.
- Wet the plants. Saturate landscaping with fresh water before and after so any splash is diluted.
- Apply the cleaning solution at low pressure, working from the bottom up so it does not streak, then from the top down on the rinse.
- Let it dwell. The solution needs time to kill the growth; scrubbing a dry wall is not the same.
- Rinse thoroughly and gently, keeping the spray angled down so water is not driven under trim or into joints.
Many soft-wash mixes use diluted sodium hypochlorite, the active ingredient in household bleach. It works well on organic growth, but strong runoff can burn leaves and damage landscaping, so pre-wetting plants and keeping the mix diluted matter. Where the wash water ends up is also a local-rules issue; see our explanation of Miami-Dade wash water rules.
When to stop and look at the wall instead
Cleaning shows the wall as it really is, and sometimes it shows a problem. Get a licensed professional to look at the stucco before or instead of washing if you see any of the following:
- Cracks wider than a hairline, or cracks that appear to be getting wider.
- Stair-step cracks that follow the mortar joints in the block.
- Bubbling or peeling paint, or soft, crumbling areas.
- Persistent white deposits or damp-looking patches that return after cleaning.
Thin, stable hairline cracks are common and usually cosmetic, but they still let in water if left unsealed. Washing is not a repair, and a freshly cleaned wall with an open crack can take on more water than a dirty one.
Washing before repainting
A clean wall is essential before new paint, and the drying time matters just as much as the wash. If a repaint is the goal, read our guide to washing a Miami house before painting, which covers drying time, lead paint on older homes and sequencing with the painter.
How often and what it may cost
In Miami's warm, humid, rainy climate, shaded walls can show growth within a year or two, while sunny walls may stay clean longer. Sprinkler overspray, tree cover and nearby water accelerate staining. Whole-house soft washing is usually priced by the job or by the size of the home, and prices vary widely with height, access and condition, so treat any figure as a starting point and check it with the provider. Our pressure washing cost guide lists typical ranges and what a written quote should include, and the checks in choosing a pressure washing company apply here too.
Keeping stucco clean longer
- Aim sprinklers away from the walls.
- Trim shrubs and trees so air and sun reach the surface.
- Extend downspouts so they do not splash the base of the wall.
- Keep sealant around windows and trim in good condition.
- Rinse off salt and dust after storms and seal small cracks promptly.
Frequently Asked Questions
Can I pressure wash my stucco house?
It is possible with the right equipment and technique, but it carries real risk. A low-pressure soft wash is the safer standard, and EIFS or cracked walls should not be washed with a strong jet at all.
Will washing stucco remove the paint?
It can if the pressure is too high or the paint is already failing. Peeling or chalky paint may come off even with a gentle wash, which is a sign the wall needs repainting rather than more cleaning.
How can I tell if I have real stucco or EIFS?
Real cement stucco feels hard and solid when you knock on it. EIFS often sounds hollow because it sits over foam board. If you are not sure, ask a contractor or check the home's construction records before cleaning.
Why do the black streaks keep coming back?
Miami's humidity and rain keep growth active, especially in shade or near sprinklers. A soft wash that kills the growth lasts longer than scrubbing, but it will return if the walls stay damp.
Should I worry about the cracks before cleaning?
Thin, stable hairline cracks are common. Wider, spreading or stair-step cracks, or damp patches and white deposits, deserve a professional inspection before the wall is washed.