Pressure Washing vs Soft Washing: When to Use Each (2026)

Two different techniques. Two different chemicals. Two very different surfaces where each one actually works. Here's the field guide to knowing which to use when, and how to price each.

Pressure washing — the short version

Pressure washing uses high-pressure water (1500-4000+ PSI) to physically blast dirt, mildew, and grime off hard surfaces. Chemical is minimal or none. Best for concrete, brick, wood decks, and masonry.

When to pressure wash

• Concrete driveways, sidewalks, patios: Yes. 3,000-4,000 PSI with a surface cleaner.
• Brick walls: Yes, if the mortar is intact. 2,500 PSI max — too high will strip mortar.
• Wood decks: Yes with a wide fan tip, 1500 PSI max. Too close or too high will splinter wood.
• Composite decking: Low pressure (1500 PSI) only. Some manufacturers void warranty at higher PSI.
• Stone: Yes, but test a small area first. Some sandstones degrade under pressure.

Soft washing — the short version

Soft washing uses low pressure (~100 PSI, basically a garden hose) with a chemical mix that does the cleaning work. The chemical — usually sodium hypochlorite (SH) plus a surfactant — kills algae, mildew, and mold at the spore level. Best for surfaces where high pressure would damage.

When to soft wash

• Asphalt shingle roofs: Always. Pressure washing a roof strips granules and voids warranties. Always soft wash.
• Vinyl / aluminum siding: Soft wash. High pressure gets behind panels and into the wall cavity — major moisture problem later.
• Stucco / EIFS: Soft wash. High pressure cracks stucco finish.
• Painted wood: Soft wash unless you want to strip the paint.
• Screens / awnings / delicate fabric: Soft wash.

The mix (soft wash)

Standard house wash mix:

• Sodium hypochlorite (SH) 12.5%: ~1 gallon
• Water: ~4 gallons (adjust to 1-2% final SH concentration)
• Surfactant (Elemonator or similar): ~2-3 oz

Stronger roof mix (for heavy algae):

• SH 12.5%: ~2 gallons
• Water: ~3 gallons (3-4% SH final)
• Surfactant: ~3-4 oz

Always wet the ground and any plants before applying. SH will yellow or kill vegetation if you don't.

Pricing differences

Soft washing is typically priced higher per square foot than pressure washing because:

• Chemical cost is meaningfully higher (a gallon of SH is ~$5, plus surfactant).
• Technique is more specialized. Fewer operators know it.
• The liability on roofs is higher if something goes wrong.

Typical rates:

• Driveway (pressure): $0.15-$0.30/sq ft
• Roof (soft wash): $0.35-$0.60/sq ft — plus pitch correction
• House siding (soft wash): $0.15-$0.25/sq ft of wall area

The mistake most new crews make

Trying to pressure-wash a roof or siding because "my pressure washer has a low-pressure mode." It doesn't work. Pressure alone doesn't kill algae or mildew — it just knocks off the surface layer, which grows back in 6 months. Soft washing kills the spores and keeps the surface clean for 2-3 years.

If you're only offering pressure washing, you're leaving the highest-margin services (roofs, siding) on the table. Add soft washing to your menu the moment you can afford the $400-800 pump setup.

Quick reference table

When you're quoting on-site and need to remember:

• Rough, durable surface + just needs dirt removed: Pressure wash.
• Delicate surface OR organic growth (algae, mildew): Soft wash.
• Roof, any kind: Always soft wash.
• Siding, any kind: Almost always soft wash.

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