Cost comparison
Asphalt architectural shingle: $3.50-$5.50 per sq ft installed in Portland. Metal standing seam: $9-$16 per sq ft installed. Metal stone-coated steel: $7-$11 per sq ft installed. The metal premium is 2-3x asphalt at install time. Over a 30-year horizon, metal lasts 40-60 years vs 25-30 for asphalt; the lifecycle math narrows but rarely fully closes the gap in Portland where asphalt performs well in the climate.
Lifespan
Asphalt architectural in Portland: 22-30 years for standard, 28-35 years for premium. Metal standing seam in Portland: 40-60 years. Metal stone-coated steel: 35-50 years. Metal lasts longer because the metal panels don't have the same wet-cycle granule erosion vulnerability that asphalt does. The trade-off is that metal panels can suffer cosmetic dents from hail or limb impact that asphalt would absorb invisibly.
Aesthetic fit
Asphalt fits virtually any home era from 1900 to present, with designer lines (Camelot II, Highland Slate) extending to heritage looks. Metal fits modern, mid-century modern, contemporary, and Pacific Northwest cabin/lodge architecture; it can look out-of-place on traditional Craftsman or English Cottage homes unless used as accent (porch roof, dormer). For most Portland heritage homes, asphalt is the better aesthetic fit; for modern and contemporary homes, metal is often preferred.
Performance differences in Portland climate
Metal advantages: longer lifespan, fire-resistant (Class A), snow/ice shedding, no algae or moss adhesion (the smooth metal doesn't hold biological growth). Asphalt advantages: cheaper repair (single shingle replacement vs metal panel replacement), more impact-tolerant for canopy-heavy lots, easier color match for partial replacement, lower install cost, broader installer pool. In PNW's wet climate, both perform well; the moss/algae resistance of metal is a genuine advantage on heavy-canopy lots.
When asphalt wins
(1) Traditional architectural style (Craftsman, Tudor, English Cottage, Colonial). (2) Budget-constrained replacement where 25-30 year life is sufficient. (3) Properties planned for sale within 10 years (you don't capture the long-life metal value). (4) Canopy-heavy lots where limb impact resistance matters more than longevity. (5) Repairs on existing asphalt roofs where matching the original system is cheaper than full replacement.
When metal wins
(1) Modern, contemporary, or mid-century modern architectural style. (2) Long-tenure ownership where 40-60 year lifespan delivers strong lifecycle economics. (3) Wildfire-exposed properties (rare in Portland metro but real in Forest Park edges and west of West Hills). (4) Properties where moss/algae management is a recurring frustration. (5) Owners who value the energy reflectance of light-colored metal (modest effect in PNW but real).