What is soft washing?

Soft washing emerged as the right approach for cleaning surfaces that high-pressure washing damages. The pressure is dramatically lower (50-500 PSI vs 3,000-4,000 PSI for traditional pressure washing), and chemistry does the cleaning work instead of force.

When soft washing is correct:

• Roof cleaning: high pressure damages asphalt shingles by stripping granules. Soft wash with sodium-hypochlorite (diluted bleach) solution kills algae and lifts streaks without removing granules.
• Vinyl + composite siding: high pressure can force water behind siding panels, causing moisture damage. Soft wash cleans the surface without water intrusion.
• Wood decks and fences: high pressure raises wood grain and causes splintering. Soft wash with appropriate cleaner cleans without damage.
• Stucco: high pressure can chip stucco. Soft wash cleans without damaging the finish.
• Older or painted surfaces: where high pressure would damage finish.

When traditional pressure washing is correct:

• Concrete driveways and walkways: high pressure (2,500-3,500 PSI) is appropriate
• Brick and stone: usually pressure-resistant
• Heavy oil and grease removal from concrete: pressure + degreaser
• Commercial graffiti removal: high pressure with appropriate chemistry

The chemistry side:

Soft wash solutions vary by surface and contamination:

• Roof algae (Gloeocapsa magma): sodium hypochlorite (4-12% concentration) with surfactant
• Mildew/mold on siding: sodium hypochlorite or hydrogen peroxide-based cleaner
• Wood deck cleaning: oxalic acid (brightener) or sodium percarbonate (oxygen bleach)
• Concrete oil stains: degreaser + low pressure rinse

Application is typically with a chemical pump system or downstream injector at the wand.

Pricing:

• House soft wash (1,500-2,500 sq ft, exterior): $200-$500
• Roof soft wash (residential): $300-$700
• Deck cleaning + brightening: $0.75-$2.00 per sq ft
• Full house exterior package (siding + walkway + driveway): $400-$800

Required expertise:

Soft washing chemistry is real chemistry — sodium hypochlorite at the wrong concentration kills landscaping or strips paint. Operators should:

1. Know the right concentration for each surface (varies) 2. Pre-wet adjacent vegetation to prevent damage 3. Rinse plants and grass after the chemical application 4. Not soft-wash in extreme heat (chemicals evaporate before working) 5. Wear appropriate PPE (sodium hypochlorite is hazardous to skin and lungs)

Many state contractor licensing boards now require certification for chemical-application services like soft washing.