How Often Should You Pressure Wash Your Home in the Pacific Northwest?

Short answer: most homes around Lake Stevens and the Puget Sound should be washed once a year, with roofs on a slightly shorter cycle than the “every few years” advice you read online. Our rain, marine humidity and evergreen canopy push moss and algae faster than almost anywhere else in the country.

Here’s a realistic schedule, followed by the signs that mean you shouldn’t wait for the calendar.

Recommended frequency by surface

House siding — every 12 months

An annual house wash keeps algae and mildew from getting a foothold, protects the finish, and stops the green film that dulls your color. Homes under heavy tree cover or near the water often benefit from a lighter touch-up wash mid-year.

Roof — every 1 to 2 years (soft wash only)

In the PNW, roofs grow moss and lichen, not just black streaks — and moss is the bigger threat. A professional roof soft wash kills it at the root, then a full rinse clears the loosened growth. High pressure strips granules and voids most shingle warranties, so a soft wash is the method ARMA and the shingle makers call for. Left alone, moss lifts shingle edges and traps water until the deck rots.

Deck and patio — every 12 months

Wood and composite both grow a slick green film here and stay damp for months. An annual cleaning keeps the surface safe underfoot and is essential prep if you plan to stain or seal.

Driveway, walks and concrete — every 12 months

Flatwork collects moss in the shade, needle and leaf tannin, dirt and oil near the garage. Once a year keeps it bright; wait longer and the staining sets in.

Gutters — twice a year

With this much conifer debris, spring and fall clean-outs are the realistic minimum. Bundle the a gutter-brightening add-on with your annual house wash.

Fences — every 1 to 2 years

Signs you’re already overdue

Moss clumps or black streaks on the roof, or moss growing in the gutters
Green or black patches on siding, especially on the north and shaded sides
A chalky residue on your hand when you wipe the siding
Slippery spots on the deck, steps or walkway — a genuine slip hazard
Concrete gone from gray to green-gray or black in shaded areas
You’re listing the house — a wash is one of the highest-ROI things you can do before photos

Does frequent washing damage surfaces?

Not when it’s done correctly. Damage comes from too much pressure on the wrong surface, not from regular cleaning. The right method — soft washing for roofs and siding, controlled pressure for hardscapes — is gentle enough to repeat every year for the life of the home. Regular gentle cleaning is far easier on your exterior than letting moss dig in and then blasting it off.

A low-effort maintenance plan

Once a year: house wash + gutter clean + driveway and walks, in one visit.
Every 1–2 years: add the roof soft wash and moss treatment to that visit.
Twice a year: gutter clean-outs (spring and fall).
As needed: deck cleaning before you re-stain.

Bundling into a single annual appointment is cheaper per surface and keeps the whole property on the same clock. Olson Pro Wash offers recurring plans that lock in the lower per-visit rate.

Not sure where your home stands? Send a few photos and we’ll tell you what needs attention now and what can wait.