PNW rain damage: what nine months of Portland rain does to your home
Water intrusion, dry rot, and moss aren't optional in Portland — they're annual. Here's what to check before the next winter, and when to bring in a contractor.
If you own a home in Portland, water is the slow-motion enemy. Not the flash-flood kind — the drip-drip-drip kind that finds its way behind your siding, under your deck boards, and into the crawl space, and quietly turns Douglas fir framing into something you can push a screwdriver through.
Every fall we get calls from homeowners who thought their roof was fine, their siding was fine, their gutters were fine — until they weren't. The tell is almost always the same: a soft spot in a windowsill, a musty smell in a closet on an exterior wall, or paint that started bubbling near a downspout.
The five spots we check first on a PNW restoration walkthrough: (1) any exterior wall directly under a roof valley — that's where water concentrates when leaves clog the gutter above; (2) the bottom two feet of siding on the north and west sides of the house — chronically wet, rarely inspected; (3) window trim, especially older wood-framed units that were painted, not replaced; (4) the underside of every deck and stair — moss is your early warning system; and (5) crawl space perimeter joists, which rot from the top down where the sill plate meets the foundation.
The pattern to watch for is not "is it wet today" — it's "is it drying out between rain events." A wall that never fully dries between October and May will rot. Full stop. Ventilation and drainage matter more than any single material choice.
If you catch it early, restoration is straightforward: cut back to sound wood, replace the flashing that failed, prime and re-side. If you catch it late — after the sheathing is gone and the framing is compromised — you're into structural work, and the cost triples. Every year we spend the first two weeks of September on preventive walkthroughs for homeowners who want to know what needs attention before the rain starts. Free. No pressure. Just a punch list.
If you're seeing any of the five signs above, get eyes on it before November.