Most of what people call “pressure washing a building” shouldn’t involve much pressure at all. If the surface is painted, coated, stucco, EIFS, or a roof, high pressure is how you turn a cleaning bill into a repair bill.
The 60-second definition
Soft washing cleans with chemistry instead of force. A low-pressure rinse, roughly garden-hose strength, applies a detergent solution (typically a sodium-hypochlorite blend with surfactants) that kills the organic growth causing most building staining: algae, mildew, lichen, and mold. The solution does the work; the rinse carries it away.
Pressure washing cleans with mechanical force: thousands of PSI blasting grime off hard surfaces. It’s the right tool for concrete, stone, and steel. It’s the wrong tool for almost everything above your building’s first floor.
Why it matters for your building
That black streaking is alive, not dirt. The dark stains on siding, stucco, and roofs are usually Gloeocapsa magma (algae) and mildew colonies. Blast them with pressure and you remove the visible growth but leave the roots, so the staining returns in months. Soft washing kills the organism. Results routinely last 2–4 years, versus a year or less for pressure-only cleaning.
Delicate surfaces can’t take PSI. EIFS and stucco can be gouged or forced full of water by high pressure. Painted surfaces strip and oxidized siding streaks permanently. Roof shingles lose granules, and most roofing manufacturers void warranties over pressure washing. Every one of those surfaces soft washes beautifully.
Wind-driven spray, controlled. Professional soft washing meters the mix, controls overspray, pre-wets and rinses landscaping, and manages runoff. This is chemistry work. The license to operate is knowing the dilution, dwell time, and neutralization, not owning a pump.
Where the drone comes in
Traditional soft washing still has the access problem: someone has to carry that wand up a lift, a rope, or, worst of all, onto the roof. Falls, not chemicals, are the dangerous part of the job.
Our aircraft apply soft-wash chemistry with a consistent standoff distance and application rate across an entire facade or roofline, including church steeples, tower crowns, and the strip above the reach line where lift-based washes visibly stop. Nobody walks your roof. Nobody hangs off your parapet.
Quick reference: which wash does your surface need?
| Surface | Method |
|---|---|
| EIFS / stucco / Dryvit | Soft wash, always |
| Painted or coated facades | Soft wash |
| Roofs (all types) | Soft wash, never pressure |
| Brick and masonry | Soft wash first; spot pressure for carbon staining |
| Concrete flatwork, decks | Pressure wash |
| Metal panel | Soft wash (low pressure protects coatings) |
If a contractor quotes one method for the whole property, ask why. The right answer for most commercial buildings is both: chemistry on the vertical, pressure on the flatwork.
Questions this answers
What is soft washing?
Soft washing cleans with chemistry instead of force. A low-pressure rinse (roughly garden-hose strength) applies a detergent solution that kills the algae, mildew, lichen, and mold causing most building staining. The solution does the work; the rinse carries it away.
Is soft washing safe for EIFS and stucco?
Yes, it's the recommended method. EIFS and stucco can be gouged or forced full of water by high pressure, so every one of those surfaces soft washes beautifully instead.
How long do soft-wash results last?
Routinely 2–4 years, versus a year or less for pressure-only cleaning, because soft washing kills the algae organism at the root instead of just blasting off the visible growth.