Every spring I get the same call: "Gus, my siding has green streaks, can you power wash it?" Usually the answer is that it needs the opposite of power. Those streaks aren't just dirt — they're living mold, mildew, and algae, and if you hit them with a pressure wand you'll strip the growth off the surface, drive water where it doesn't belong, and leave the roots to grow right back. — Gus
The difference in one minute
Soft washing uses low pressure — under 500 PSI, gentler than a garden hose — paired with a cleaning solution that actually kills the mold and algae at the root, so it stays gone longer. Power (or pressure) washing uses high pressure, 2,000–3,000 PSI, and is the right tool for hard, tough surfaces. The trick is matching the method to the surface.
| Surface | Right method |
|---|---|
| Vinyl, wood, and fiber-cement siding | Soft wash |
| Stucco and delicate trim | Soft wash |
| Concrete driveways & walkways | Pressure wash |
| Brick & masonry patios | Pressure wash (adjusted) |
| Composite & wood decks | Low pressure + cleaner, then dry before staining |
Why high pressure on siding is a mistake
I've been called in to fix the aftermath more than once. Too much pressure on siding will force water up behind vinyl and into the wall, gouge and furr up soft wood clapboard, and blast out caulk and glazing that was doing its job. You end up trading a cosmetic problem for a moisture problem — and moisture is what causes paint to fail in the first place.
What New England throws at your house
Our climate is hard on exteriors. Winter road salt splashes up onto the lower siding, spring pollen coats everything and feeds mold, and any wall that sits in shade or under trees stays damp long enough for algae to take hold. Homes on the north side of a lot or tucked into the tree line here in Western Mass almost always show it first.
A wash is also step one before painting
Paint can't grip a dirty, chalky, or mildewed surface. Every exterior paint job we do starts with a proper wash — skip it and even the best paint peels early. If you're planning to paint this year, the wash is already built into the job.
How often should you wash?
For most Western MA homes, once a year keeps the growth from ever getting established. Houses with heavy tree cover or a lot of shade do better with two visits a year. Nationally, a full house wash tends to run a few hundred dollars depending on size and access — a small maintenance cost that protects a much bigger investment in your siding and paint. We'll give you the honest number for your home for free.
Frequently Asked Questions
Will soft washing really get my siding clean without high pressure?
Yes — the cleaning solution does the work, not the pressure. It kills mold and algae at the root, so the siding comes clean and stays clean longer than blasting it off ever would.
Can power washing damage vinyl siding?
It can. High pressure drives water up behind the panels and into the wall, and can crack or dull older vinyl. That is exactly why we soft wash siding instead.
Does washing kill the mold or just remove it?
A proper soft wash kills it. Plain pressure only knocks the surface growth off and leaves the roots, so it comes back fast — often within a season.
How often should I wash my house in New England?
About once a year for most homes, or twice a year if you have heavy tree cover, shade, or a lot of pollen. Regular washing can also add two to three years to the life of your paint.
Get a free estimate
No pressure, no obligation — just a straight answer for your home from a local, licensed crew.