Soft washing is a low-pressure exterior cleaning method that uses specialized biodegradable chemical solutions to kill and remove organic growth — including algae, mold, mildew, lichen, and bacteria — from surfaces that would be damaged by high-pressure water.
The key distinction: pressure washing removes contaminants with force. Soft washing removes them with chemistry. This makes soft washing far safer for delicate surfaces like vinyl siding, wood, roofing, stucco, and painted surfaces — and produces longer-lasting results because the organisms are killed rather than merely displaced.
| Factor | Soft Washing | Pressure Washing |
|---|---|---|
| Pressure | Under 100 PSI | 1,500–4,000 PSI |
| Primary method | Chemistry | Mechanical force |
| Kills algae/mold? | ✓ Yes — at root level | ✗ Surface only |
| Result duration | 2–5 years | 3–12 months |
| Safe for siding? | ✓ Yes | ⚠ Depends on technique |
| Safe for roofs? | ✓ Yes (required) | ✗ Voids shingle warranty |
| Safe for concrete? | ⚠ Less effective | ✓ Ideal |
The active ingredient that kills algae, mold, mildew, and bacteria at the cellular level. Concentration varies by surface — roofs get a stronger solution than siding. Breaks down into water and table salt after application.
Reduces water's surface tension, allowing the cleaning solution to penetrate organic growth more effectively. Also acts as a "soap" to help lift dirt and grime from the surface.
Neutralizes the cleaning solution before and after application to protect landscaping. We pre-wet and post-rinse all plant beds when working near vegetation.
Optional additives that slow the return of biological growth after treatment. Used on surfaces that are highly susceptible to rapid recolonization (heavy shade, high humidity areas).
Soft washing is not the right tool for every job. For these surfaces and stain types, high-pressure washing is the more appropriate choice:
Hard concrete surfaces require mechanical pressure (1,500–4,000 PSI) to remove embedded oil and tire marks. Chemistry alone is insufficient for these stains.
Rust, paint, and deep oil stains require high-pressure rotary surface cleaners combined with specific chemistry. Soft washing pressure cannot mechanically extract these.
Gum requires focused high pressure to shear from concrete surfaces. No chemical solution dissolves bonded gum effectively.
Freshly poured concrete (under 30 days old) should not be pressure washed at all — neither high nor low pressure — until it has fully cured.
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