Soft Washing vs. Pressure Washing: What's the Difference?
Both methods get surfaces clean, but they work in very different ways. Using the wrong one on the wrong surface is one of the most common ways roofs and siding get damaged.
Pressure washing: high pressure for hard surfaces
Pressure washing uses a concentrated, high-pressure stream of water to blast off dirt, algae, and grime. It works best on tough, hard surfaces like concrete driveways, sidewalks, patios, and many types of pavers.
The same force that makes it great on concrete makes it risky on softer materials. It can etch wood, strip paint, and push water where it doesn't belong.
Soft washing: low pressure plus a cleaning solution
Soft washing uses about the same pressure as a garden hose, combined with a cleaning solution that kills moss, algae, and lichen. Instead of blasting growth off, the solution breaks it down, then it's gently rinsed away.
Because it kills growth at the root, a soft wash usually stays clean longer than pressure washing, which can leave roots behind to grow back.
Why you should never pressure wash a roof
Asphalt shingles are covered in granules that protect them from sun and weather. High pressure knocks those granules off, which shortens the roof's life. Shingle manufacturers generally warn against pressure washing, and doing it can put your warranty at risk.
Cedar shakes can splinter and fuzz under high pressure.
High pressure can also force water up under shingles and into the roof deck.
For moss, which is a constant problem in the Northwest, the right approach is a soft wash and moss treatment. Some dead moss may take a few rain cycles to fully wash away after treatment.
Quick guide: which method for which surface
- Concrete driveways, sidewalks, patios: pressure washing
- Roofs (asphalt or cedar): soft washing
- Vinyl, painted wood, and fiber cement siding: soft washing
- Stucco: soft washing
- Wood decks and fences: low pressure, adjusted for the wood
What about my plants?
A careful crew protects your landscaping by wetting plants before the cleaning and rinsing them afterward, and by controlling where the runoff goes. Ask any company you hire how they handle this.
Not sure which method your home needs? We'll look at your roof, siding, and concrete and recommend the right approach, with a free estimate.