Mercer Island sits in the middle of Lake Washington, so almost every street runs downhill to the water. Lots are steep, the tree canopy is old and tall, and the shoreline lots have banks that move when runoff from the street above has nowhere else to go. The black film on a lake-view patio is normal. The wash water should not be a hose of cleaner and grime down the bank.
King County · ZIP 98040
Clean the patio without sending the spoil downhill
We rinse and treat surfaces up top, and we break up the flow so it is not a single dirty stream at the shore. Furniture gets moved, not blasted around. Covers and outdoor fabric are not a pressure-wash surface.
Docks, if we touch them, are a light wash. Old wood on a dock can be destroyed in a minute with the wrong tip. We treat them as wood, not as a driveway.
The ground in Mercer Island
Most of our work here is on slopes. A patio or terrace has to be cut into the hill with a real base and a drain behind any wall, or the first wet winter shows where the water wants to go. On the lakefront lots we keep native shrubs on the bank, because they hold the soil better than lawn, and we take runoff to a drain or a rain garden instead of letting it sheet over the edge.
The city is strict about removing large trees and about work near the shoreline. We check what needs a permit before we cut or dig, and we plan around the trees you have to keep. Under those firs and cedars the ground is shady and mossy, so we often turn worn-out lawn into planting beds and stone paths that stay clean year-round.
How we do the work
Most of what people call pressure washing here is organic film: the black and green on the north side, the walks, the fence. The fix is the right tip, the right distance, and often a wash that kills the growth so it does not return in a month. A zero-degree tip on a soft wood deck is how you get a furred, ruined deck.
We do not drive water up under lap siding or into a vent to prove the washer is strong. High pressure is for concrete that can take it. Wood, paint, and mortar joints get a softer approach.
What we look at first
- What the surface is
- Where the water will run
- Plants and outlets we need to protect
- Whether the black is mildew that needs a treatment, not just a blast
Wood versus concrete
Concrete can take a stronger wash. Cedar decks, fences, and soft siding cannot. If we raise the grain, the surface holds more dirt afterward. We would rather leave it a shade less bright than furred.
Treatment
A wash that kills the algae and mildew, applied and rinsed, is why the surface stays clean longer than a blast. We use it where the film is biological. We do not soak your vegetable bed in it. Plants get rinsed.
What will not come out
Rust, deep oil, and etching that is already in the concrete. We can fade some of it. We will not promise a new slab. Paint that is loose will leave with the dirt, and you will see the bare spots. We point those out first if we can.
More from this crew
- Pressure washing across the region
- Patio installation in Mercer Island
- Paver installation in Mercer Island
- Fence installation in Mercer Island
- Yard cleanup in Mercer Island
- Pressure washing in Sammamish
Sources for the climate and the water
- USDA plant hardiness map for choosing plants that can take a King County winter.
- EPA WaterSense on watering less once a lawn or a new planting is established.
- EPA Soak Up the Rain on keeping roof and yard water from becoming someone else’s problem.
