How long a roof actually lasts on the Puget Sound
The number on the shingle wrapper was earned in a laboratory, on a roof that dries between wettings. A Sound-area roof spends October to May damp, its shaded slopes damper still — and the gap between the two slopes of one house here can be a third of the covering’s life.
What shortens a roof’s life here
Standing moisture does the most work: a surface that stays wet grows moss, and moss holds more water, lifts edges and pries at courses — a feedback loop that ages the shaded half of a roof years ahead of the open half. Debris compounds it, matting in valleys and gutters and keeping the drainage paths damp. And the attic works from below: an under-vented attic in this climate condenses the household’s winter moisture onto the underside of the decking, so the roof can be aging on both faces at once.
What extends it, and how to read where yours is
The extenders are unglamorous: moss treated in the fall before it anchors, valleys and gutters cleared on a conifer schedule, zinc or copper at the ridge, boots and flashing replaced when they crack rather than when they leak, balanced attic ventilation, and a correctly installed covering in the first place — installation quality moves lifespan more than brand choice does.
Reading your own roof: compare the north slope to the south one from across the street — the shaded side is the honest one; check the gutters for granules; look at the eaves and fascia for staining or softness, because Sound-area coverings finish at the edges first. And note the age of the street: on plat-era housing, when neighbouring roofs of the same vintage start turning over, yours is on the same clock. A covering in its mid-teens here has earned a proper evaluation even if nothing has leaked yet.
Next step: When an inspection earns its price