Metal Roof vs. Asphalt Shingles: Best Island Roof 2026

Choosing between a metal roof and asphalt shingles is the single biggest decision most San Juan Islands homeowners face when it is time to re-roof. Out here the answer is not the same as it is on the mainland: salt air, west-side wind, and moss under the Douglas firs change the math. Here is an honest, island-tested comparison so you can spend your money once.

For most San Juan Islands homes, a standing-seam metal roof is the best long-term value. It lasts 50 or more years, sheds our roughly 40 inches of annual rain, resists moss, and stands up to salt air when it is coated correctly. Quality architectural asphalt shingles are the smart pick when a tighter budget or shorter ownership horizon drives the decision.

Metal roof vs. asphalt shingles: the quick comparison

The table below uses island-adjusted ranges — the numbers we actually see on San Juan, Orcas, Lopez, and Shaw, where ferry logistics and off-island disposal push costs above comparable mainland jobs. Treat every figure as an estimate for planning, not a quote.

How long does each roof last on the islands?

Lifespan is where metal separates itself. A properly installed standing-seam metal roofing system routinely reaches 50 years or more in the San Juan Islands, meaning many homeowners install it once and never re-roof again. Architectural asphalt shingles are rated for 25 to 30 years, but our climate is hard on them: constant moisture, moss colonies on north-facing slopes, and salt-laden air near the water tend to pull real-world island life closer to 20 to 25 years. On a heavily shaded lot under mature Douglas fir, expect the lower end.

That gap matters because it drives the true cost of ownership. One metal roof can outlast two — sometimes three — shingle roofs on the same house.

What does each roof really cost out here?

Upfront, asphalt shingles win. A full asphalt shingle roofing install runs roughly $9,000 to $24,000 island-adjusted, while a standing-seam metal roof lands between $14,000 and $45,000 or more depending on size, pitch, panel profile, and access. Ferry staging for crews and materials, plus hauling old roofing off-island for disposal, is baked into both — it is the reason an island re-roof costs more than the same job in Anacortes.

Cost per year tells the more useful story:

• Metal: spread across a 50-plus-year life, even a $30,000 roof works out to roughly $250-$600 per year.
• Asphalt: a $16,000 shingle roof replaced every 20-25 years lands closer to $400-$1,000 per year once you factor a second replacement.

Add the moss treatments and periodic repairs shingles need on shaded island roofs, and metal’s long-run economics get stronger. Neither is “cheap,” but they answer different questions: lowest check today, or lowest cost over the life of the home.

Which holds up better to salt air and west-side wind?

If your home sits near saltwater — think Roche Harbor, Deer Harbor, or a Lopez shoreline — this is the deciding factor. Salt air corrodes ordinary metal and degrades fasteners, so we specify marine-grade Kynar 500 / PVDF coatings on 24-gauge steel with corrosion-resistant fasteners. Built that way, metal shrugs off salt exposure that would age other materials fast.

Wind is the other island reality. The west side of the islands sees gusts roughly 20% stronger than Anacortes, and heavy weather peaks in November. Interlocking standing-seam panels have very few edges for wind to catch, so they perform exceptionally in exposed, waterfront, and ridgetop locations. Asphalt shingles hold up well when they are installed with proper nailing and starter courses, but individual tabs can lift or tear in the strongest west-side gusts, which is exactly the kind of damage our storm and emergency repair crews get called for after a big blow.

Which roof resists moss and 40 inches of rain?

Both materials shed our 40 inches of annual rain when flashing and slope are done right — this is the Pacific Northwest, so drainage is non-negotiable. The difference is moss. A metal roof’s smooth surface gives moss and algae almost nothing to grip, and debris slides off shaded slopes instead of composting into a green mat.

Asphalt shingles are the opposite: their granular surface and the shade of north-facing slopes under Douglas fir create ideal moss conditions. That is manageable — moss treatment and roof cleaning plus zinc or copper ridge strips keep regrowth in check — but it is ongoing upkeep that metal largely avoids. Two rules apply to either roof: install a zinc or copper strip near the ridge so rain carries metal ions down the slope, and never pressure-wash shingles, which strips the protective granules and shortens their life.

Repairability and curb appeal

Shingles are easier and cheaper to repair. A localized leak or a few wind-torn tabs are a quick, low-cost fix — swap the damaged shingles and move on. Metal repairs are less frequent but more specialized; a damaged panel usually means matching color and profile rather than patching, so the right installer matters more.

On appearance, it comes down to taste. Metal reads clean and modern, suits farmhouse and contemporary island homes, and comes in a wide palette of Kynar colors that hold their finish for decades. Architectural shingles bring depth and traditional texture that blends naturally into wooded lots around Eastsound, Olga, and Friday Harbor. Both are handsome; neither is “better” here.

The verdict: which should you choose?

Choose standing-seam metal if this is a forever-home, if you are near saltwater, or if you simply never want to think about your roof again. It is the best long-term island roof — the lifespan, moss resistance, and salt-and-wind performance justify the higher upfront cost, and the cost-per-year math usually favors it over the life of the house.

Choose quality architectural asphalt shingles if budget is the binding constraint, if you expect to sell within five to ten years, or if you want a traditional look that matches the neighborhood. Well-installed architectural shingles are an honest, capable roof for our climate; they simply ask for a bit more maintenance and an earlier replacement.

Still on the fence? That is normal, and it is exactly what a roof replacement consultation is for. We will look at your slopes, exposure, shade, and budget and give you straight repair-vs-replace advice — not a sales pitch.

Get your real number

Both price ranges above are for education only — an estimate, not a quote. The free on-island inspection is where you get your real number, because your roof’s size, pitch, access, and exposure decide the cost. As a licensed, bonded, and insured WA roofing contractor serving all of the San Juan Islands, we back our work with a workmanship warranty.

Ready to compare options for your home? Contact us or call (360) 205-1462 to schedule a free inspection and written estimate anywhere on San Juan, Orcas, Lopez, or Shaw.