Soft washing uses low pressure (under 500 PSI) combined with biodegradable cleaning solutions to lift mildew, algae, and grime. Pressure washing uses high pressure (1,500–4,000 PSI) to physically blast off heavy buildup. Soft wash is correct for siding, stucco, paint, and roofs. Pressure wash is correct for concrete, brick, and unfinished hardscape.
These two terms get used interchangeably online, but they're different techniques with different uses — and using the wrong one is how property gets damaged.
Soft wash — low pressure, smart chemistry
Soft washing applies cleaning solution at low pressure (typically under 500 PSI — about the same as a strong garden hose). The chemistry does the work: biodegradable detergents penetrate the biofilm, kill mildew and algae at the root, and lift staining off the surface.
It's the right method for:
- Painted siding (vinyl, wood, fiber cement)
- Stucco
- Roofs (shingle, tile, metal)
- Window screens and exterior glass
- Soft natural stone
Pressure wash — physical force
Traditional pressure washing uses 1,500–4,000 PSI to physically blast buildup off hard surfaces. It's effective on dense, durable materials where chemistry alone isn't enough.
It's the right method for:
- Concrete driveways, sidewalks, and patios
- Brick (with proper PSI calibration)
- Unsealed pavers
- Metal roll-up doors
- Heavy-duty industrial surfaces
Where pressure wash on the wrong surface goes wrong
High-PSI pressure on the wrong surface is how Bay Area homes get damaged. Common mistakes we get called to fix:
- Stripped paint from siding hit with a high-PSI fan tip
- 'Tiger striped' stucco from inconsistent pressure
- Splintered wood decks from pressure washing instead of soft washing
- Etched concrete from holding the nozzle too close
- Blown-out joint sand on pavers (which then have to be re-sanded)
How a real pro decides
On every job we identify the surface, the buildup type, and the surrounding context (paint age, plant proximity, water source, drainage). Then we match technique. Most full-property cleans use both methods — soft wash on the house, pressure wash on the driveway.
If a contractor only owns one type of equipment, they'll use it on everything — and that's where damage starts.