What pressure washing covers
- House siding. Vinyl, fiber cement and painted wood are usually soft-washed: low pressure plus a cleaning solution that kills algae and mildew, then a gentle rinse.
- Driveways and walkways. Concrete can take higher pressure, often with a rotary surface cleaner that leaves an even finish without stripes. See driveway and concrete cleaning.
- Decks and fences. Cedar and other softwoods gouge easily, so they need low pressure and the right nozzle. Composite decking has its own manufacturer guidelines.
- Patios, steps and retaining walls. Pavers, brick and stone, with care around joint sand and mortar.
Pressure washing vs. soft washing
"Pressure washing" is what most people search for, but a good provider matches the method to the surface. High pressure is for hard surfaces like concrete. Soft washing uses low pressure and a cleaning solution, and it's the safer choice for siding, painted trim and roofs (see roof cleaning and moss removal). If someone plans to blast cedar siding or an asphalt roof at full pressure, treat that as a red flag.
Why exteriors get dirty so fast around Seattle
- Long damp stretches and weak winter sun let green algae and mildew settle on the shaded north and east sides of a house.
- Tree cover drops sap, pollen and tannins that stain decks and fences.
- Moss takes hold in concrete joints and on shaded steps, where it turns into a slip hazard in the rainy season.
- Traffic leaves a gray film on houses along busy streets and arterials.
When to schedule pressure washing
Late spring through early fall is the most popular window. Surfaces dry quickly, and if you plan to paint, stain or seal afterwards you need a run of dry days. Washing still works in the rainy season, especially for slippery walkways and steps that need attention before winter, but staining and sealing should wait for dry weather. Plenty of homeowners do a full exterior wash once a year and spot-clean walkways every fall.
What affects the cost
- Which surfaces you want cleaned and how big they are; siding, driveway, deck, fence and patio are often priced separately
- Number of stories and how much of the house can be reached from the ground
- How heavy the algae, moss or staining is
- Surface type: soft wood and older paint take more care and time than bare concrete
- Extras such as deck sealing, rust or oil stain treatment, or cleaning gutter exteriors
- Outdoor water access at the property
Protecting your yard and Puget Sound
Wash water shouldn't go down the storm drain. In Seattle, most storm drains flow to local creeks, lakes and Puget Sound rather than to a treatment plant. Ask how the provider handles runoff and which cleaning products they use, especially if you have vegetable beds, a pond or pets.