Almost every homeowner who asks this has either seen, or heard about, a pressure washing job that went wrong — etched stucco, streaked paint, water inside a wall. Those are real outcomes, and they are outcomes of pressure, not of cleaning.
What "low pressure" actually means
A pressure washer cleaning concrete might run at 3,000 PSI or more. A soft wash runs at roughly the pressure of a garden hose. If you stood in front of it you would find it unremarkable. All of the cleaning power comes from a biodegradable solution that kills algae, mould, and mildew at the root and then gets rinsed away.
Surface by surface
- Stucco. Porous and easy to etch with pressure, and it happily hosts algae in its texture. Soft washing reaches into the texture without opening it up.
- Vinyl siding. The classic pressure failure is forcing water up behind the panels. Low pressure cleans the face without driving water where it does not belong.
- Painted wood and fibre cement. Pressure lifts and streaks paint, especially where it has already chalked. Soft washing does not.
- Brick. Cleans well, but old or soft mortar joints are vulnerable to pressure. Chemistry is the safer route.
- Soffits and gutters. Where the black streaking usually concentrates, and where forced water most easily gets into the roofline.
- Pool cages and lanai screens. Zero-pressure only — pressure stretches and tears screen mesh, and it is a costly thing to replace.
What about plants, pets, and grass?
This is the concern I hear most, and it is fair. The solutions used are biodegradable, but they are still cleaning solutions and they need managing. Done properly, that means pre-wetting the beds and lawn around the work area, keeping plants saturated so they take up water rather than solution, and rinsing everything down thoroughly afterwards. Pets should be inside while the crew works, and back out once the rinse is complete and surfaces are wet-clean. In 15 years I have not lost a customer’s landscaping doing it this way — but I have been called out to fix jobs where none of those steps were taken.
What actually goes wrong on a bad job
- Oxidation streaking on older vinyl and aluminium, when a chalked surface is cleaned unevenly.
- Water intrusion behind siding or into soffits from too much pressure at the wrong angle.
- Etched or “fuzzed” stucco, which cannot be undone and shows permanently in raking light.
- Dead plants from solution that was never diluted, pre-wetted, or rinsed.
- Growth returning within months, which means the algae was rinsed off rather than killed.
A fair question to ask any contractor
“What are you putting on my house, and how are you protecting my plants?” Anyone who soft washes regularly will answer both without hesitating. A vague answer to either is the signal to keep looking.