Composition, cedar, or metal in this climate

Portland asks more of a roof than most metros: roughly 36 inches of rain a year at the airport gauge, more like 60 in the West Hills, with about 90 percent of it falling mid-October through mid-May. Roofs here stay damp for months at a stretch, and the material choice changes how that wet season treats you.

Composition (asphalt shingle)

The default; most of the metro's houses wear it. Twenty to thirty years is a typical run, and the wet season shaves the low end when moss and debris hold water against the surface. Black streaks (the Gloeocapsa algae) show on shaded slopes after a few years, and moss pressure is highest on north-facing and tree-covered roofs. Cheapest to install, easiest to repair piecemeal, and every roofer in the metro works it.

Cedar shake

The beautiful option with a maintenance bill attached. Cedar breathes, insulates, and suits the older Portland streetscape, but in this climate it needs cleaning and treatment on a schedule or it goes mossy, spongy, and thin early. Well-maintained cedar runs decades; neglected cedar fails young. The cedar shake page covers what upkeep actually involves.

Metal

The wet-weather answer. Metal sheds water instantly, doesn't feed algae or moss, doesn't rot, and handles the wind events better than tabs-and-laps do. The tradeoffs: higher upfront cost, fewer crews who do it well, and it changes the look of the house, which some neighborhoods and HOAs care about. Metal roofing covers standing-seam versus panel and what the install involves.

The decision that actually matters

Material picks the roof; the deck under it decides the job. A reroof onto soft or damaged sheathing is a different scope than a dry deck, and nobody knows which you have until the tear-off starts. Whatever direction you lean, the roof replacement page covers what the scope conversation looks like before the work starts.