01 / Facades
Building exterior washing
Stucco, block, brick, siding and trim washed clean of dust, grime and streaks.
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Guide
Why stucco streaks and grays, and how it gets washed gently.
Stucco looks crisp when it’s new and tired a few seasons later. Here’s why it streaks and grays, and how a careful wash brings the color back.
Why stucco holds onto dirt.
Stucco is everywhere on Northern California commercial buildings, from strip centers and office parks to apartment communities and medical offices. Its texture is a big part of the look, and it is also the reason the walls get dirty. Every ridge and pocket in the finish gives dust, pollen and exhaust film a place to settle.
Stucco is porous, too, so water carries dirt a little way into the surface instead of letting it bead up and roll off. Light colors, which are popular on newer buildings, show the result first.
The surroundings play a part as well. A building beside a busy road picks up exhaust film on the street side, one next to a construction site gathers dust, and one under mature trees collects pollen, sap and leaf stains. Two buildings with the same stucco can age at very different speeds.
Where the streaks come from.
The dark vertical lines under window sills, ledges, light fixtures and roof edges follow the water. Rain picks up dirt from the roof and every flat surface above, then runs down the same paths each storm, leaving a darker stripe wherever it travels. After a few winters those paths become a pattern that makes a building look older than it is.
Sprinklers leave marks of their own. Walls beside planting beds pick up a band of splashed soil and mulch along the base, and the corners where leaves collect pick up stains of their own.
Ledges, sills and the tops of trim are the worst offenders. Each flat surface holds a little dust and debris, and the first rain of the season sends it down the wall in one dark drip line.
Why shaded walls go gray or green.
North-facing walls, sides of buildings tucked against trees and walls under deep overhangs stay damp long after a rain. That lingering moisture lets a gray, green or black film grow across the texture, often starting near the ground and creeping upward. Sunny walls on the same building can look fine at the very same time.
That uneven look is the giveaway. When one side of a building reads darker than the others, shade is usually doing it, and that elevation tends to need the most time on wash day.
Washing shaded walls during a dry stretch gives them time to dry out afterward, which slows how fast the film returns. Trimming plants back from the wall helps for the same reason, letting air and light reach the stucco.
Gentle and top-down.
Stucco does not reward force. Too much pressure can scar the texture, chip edges and push water behind the finish, so Raincrest matches the pressure to the wall and lets slower, repeated passes do the work. Painted stucco gets an even lighter touch, since the goal is to clean the paint, not take it off.
Walls are washed from the top down, starting under the roofline and working toward the ground, so dirty water never runs over a section that is already clean. Doors, windows, light fixtures and electrical boxes are protected first, and the walkways below get a rinse at the end so the frontage looks finished.
If you’re writing up a full building wash, our facade cleaning scope of work shows how to list each elevation and its finish.
Cracks, patches and a coming repaint.
A wash is a good moment to look closely at the walls. Once the dirt is gone, hairline cracks, old patches that never quite matched and spots where paint is lifting are far easier to see. Note them for your maintenance team or stucco contractor, who handles the repair.
Chalky paint is worth flagging too. A chalky wall leaves a pale powder on your hand, and that powder tells a painter the coat is nearing the end of its life.
If the building is due for paint, plan the wash ahead of the painters. Our guide to pressure washing before painting covers how to line up the two crews and leave time for drying.
How often stucco needs a wash.
Most stucco buildings look their best with a full wash once or twice a year, often in late spring after the pollen has fallen. Shaded elevations and walls facing a busy road can come around more often than the rest of the building.
The schedule is set at the walkthrough and written into the quote, elevation by elevation, and supervisors check each wall before the crew packs up. See building exterior washing for the surfaces Raincrest washes, from stucco and block to brick, metal and siding.
Between full washes, entries and the lower walls by the doors can be freshened on their own, since that is where hands, carts and splashing from the walkway leave their mark first.
A few useful answers
Quick answers.
Will pressure washing damage stucco?
A wash matched to the wall leaves the texture intact. Raincrest uses gentler pressure and repeated passes on stucco, with the lightest touch on painted finishes.
Why is one side of our building darker than the others?
Shade and moisture. Walls that stay damp longer grow a gray or green film, so they darken faster than the sunny elevations.
Can the dark streaks under the windows be washed off?
Yes. They’re dirt carried down the wall by rain, and a top-down wash takes them off along with the rest of the grime.
How often should stucco be washed?
Once or twice a year suits most buildings, with shaded and street-facing walls added in between when they darken faster.
Services
Services this guide covers
Stucco walls are washed as part of a full building exterior visit.
02 / Storefronts
Storefront and entryway washing
Entrances, walkways, awnings and the concrete in front of the door, clean before you open.
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