Soft-washing cedar siding on a West Linn Craftsman

The homeowner in Willamette found us through a neighbor referral. His 1924 Craftsman on a hillside lot in West Linn had gone green on the north wall — not black mold, not rot, but a uniform algae film that made the cedar look painted. He had a quote from another company to “blast it clean” with a pressure washer.

Cedar siding does not get blasted. Ever.

The house

Two-story Craftsman off Willamette Falls Drive, mature Douglas fir and cedar in the backyard throwing shade on the north and east elevations. Original cedar lap siding on the first floor, cedar shake on the second-story gables. Painted trim, but the siding itself was natural stain — the kind where you can still see grain if you look close.

The north wall had not been cleaned in six years. The south and west faces were weathered but fine. Classic West Linn pattern: the shady side grows biology, the sunny side just fades.

What we found up close

• Green algae across roughly 340 square feet of north cedar lap — uniform, not spotty
• Lichen patches at the bottom course where splash-back from a bark-mulch bed kept the wood damp
• Fir needle debris packed behind the lower downspout bracket — holding moisture against the sill
• No soft rot — wood was sound, just dirty and damp

This was a soft-wash house wash job, not high-pressure blasting. Our cedar shake guide covers roofs, but the same rules apply to cedar siding: under 200 PSI, diluted chemistry, dwell time, low-volume rinse. High pressure strips tannins, lifts grain, and opens the wood to moisture it cannot shed.

What we did

We tarped the landscape beds, wet down the plants, and applied a low-dilution sodium-hypochlorite solution with a soft-wash pump — roughly 1.5% on cedar, not the stronger mix we use on composition shingle. Let it dwell twelve minutes. Hand-brushed the lichen at the base course. Rinsed from top down with a wide fan tip at under 150 PSI.

The whole north elevation took about two hours. We hit the east gable while we were set up — lighter algae, same method.

The difference between house washing and pressure washing is not marketing language. On cedar it is the difference between cleaning the wood and destroying it. Driveways get 2,500 PSI. Cedar gets chemistry and patience.

Why West Linn cedar needs this every few years

Hillside homes in Sunset, Robinwood, and Willamette sit in tree shade most of the year. North walls stay damp into July. Algae does not eat the wood overnight, but it holds moisture against the surface and accelerates the stain failure cycle. Clean cedar stains last longer. Dirty cedar re-stains sooner — or worse, someone pressure-washes it and you are sanding splinters instead of staining.

We recommend a soft-wash on shaded cedar every three to five years in West Linn, paired with gutter cleaning so overflow is not feeding the bottom courses.

What we sent the homeowner

Full north-wall before and after, a close-up of the lichen at the base course, and a note that the south elevation could wait another year. No upsell on the whole house — just an honest read of what each face needed.

If someone quotes you pressure washing on cedar siding in West Linn, get a second opinion. 503-995-1947 — we walk the property first and quote one flat number before any work starts.