Stucco is porous, so it soaks up dust, mildew and sprinkler water, and it shows every bit of it. High pressure is the wrong tool because force can drive water into the wall. A low pressure softwash, where a cleaning solution does the work, lifts the growth and grime without that risk.
Here’s what’s on your walls and how we handle it.
Why does stucco get so dirty?
Stucco has a rough, textured surface full of tiny pores. Dust and pollen settle into it, and moisture lingers there longer than it does on smooth siding. That’s a good setup for algae and mildew, especially on shaded walls.
Many homes across the Valley are stucco. In Porter Ranch, Valencia and Simi Valley, stucco walls with tile roofs are the norm. Light colored stucco shows dust and streaks the most.
What are the usual problems?
| What you see | What it usually is |
|---|---|
| Green or gray patches, mostly on shaded walls | Algae or mildew |
| Dull, dusty film on the whole wall | Dust and pollen, often from nearby hills or traffic |
| Gray fuzz along eaves, corners and under overhangs | Spider webs and the dust they hold |
| White or rust-colored streaks low on the wall | Sprinkler overspray and mineral deposits |
| Dark lines under windows and rooflines | Water runoff carrying dirt down the wall |
Homes against open hillside, like parts of Granada Hills, collect extra dust when the wind blows. Homes under mature trees, like many in Thousand Oaks, grow growth faster on the shaded side.
Why not pressure wash stucco?
Stucco looks tough, but it’s a coating over a wall system, and that coating can crack or erode. A pressure washer can:
- Push water into the stucco or behind it, where it can sit
- Roughen or gouge the surface, especially at hairline cracks
- Blow out caulk around windows, doors and trim
- Strip paint from painted stucco
- Leave stripes or a patchy finish
You don’t see the water that gets behind a wall, and that’s the point. The wall may look fine after a pressure wash and cause trouble later. We’d rather use a method that doesn’t ask the wall to take a beating.
We do pressure wash walkways, because plain concrete tolerates it. For house exteriors, roofs, siding, fences and decks, we softwash.
How does softwashing work on a house?
Softwashing uses low pressure and a cleaning solution. We apply the solution to the wall, let it break down the algae, mildew and grime, then rinse it off at low pressure. The solution does the cleaning, so the water doesn’t need force.
Before we start, we cover and protect what needs it and wet down plants and landscaping. After, we rinse them again. See our house washing and softwash page for the full list of what we clean.
What about trim, eaves and siding?
They get washed too. Eaves collect spider webs and dust that no one sees from the ground. Trim and fascia hold algae at the shaded edges. Siding, where you have it, gets the same low pressure treatment.
We can also wash the windows during the same visit. Our window cleaning is done by hand with purified water, and washing the walls first means dirty rinse water doesn’t land on clean glass later.
How do you protect plants and landscaping?
Plants are the first thing people ask about, and a fair question. We rinse plants and protect landscaping before and after we work, and we take extra care around planters, lawns and garden beds. If you have something delicate, a prized rose, a potted tree, a koi pond, tell us when you book.
Also tell us about pets, gates and anything you want us to avoid.
Should I wash before painting?
It’s a good idea. Paint goes on better over a clean wall, and washing removes the dust and growth that would otherwise sit under the new coat. Talk to your painter about timing, because the wall needs to be fully dry before they start, and they may have their own prep steps. We wash. We don’t paint.
How often should a house be washed?
There isn’t one answer. It depends on shade, moisture, nearby trees and how close you are to open ground.
- Sunny, dry walls in open tracts stay clean longer
- Shaded north sides and walls near sprinklers grow algae sooner
- Homes by hillside brush or dirt collect dust faster
- Light colored stucco shows everything, so it may look overdue sooner
A good rule is to take a look each spring and each fall. If you see green growth, streaks or heavy dust, it’s time. Fall is also a useful moment, before the rainy season, which we cover in our before-the-rains checklist. If the roof has dark streaks as well, read what roof algae is and how we clean it.
How do you stop sprinkler stains?
Sprinkler stains come from water hitting the wall again and again. The minerals dry on the surface and leave white or rusty marks. We can wash most of it off, but it’ll come back if the sprinklers still hit the wall. Adjust the heads to point away from the house, and the stains slow down. Walls near Encino and Northridge tract lawns often show this at the base.
What should I do before a wash?
A little prep helps the visit go smoothly.
- Close windows and doors, and let us know about any that don’t seal well.
- Move patio furniture, potted plants and decorations away from the walls if you can.
- Tell us where the water spigot is and whether any gates are locked.
- Point out cracks, loose trim or areas you’re worried about.
- Mention anything fragile, like hanging planters, outdoor lights or climbing vines.
You don’t need to be home as long as we have access to the property and water.
Get a free estimate
We wash stucco and house exteriors across the San Fernando, Santa Clarita, Conejo and Simi valleys. Estimates are free. Call (818) 913-1626 Monday through Saturday, 7am to 7pm, see our house washing and softwash page, or find your neighborhood on the cities we serve page.