Asphalt composition shingle is the default across Washington, and for most homeowners it remains a perfectly sound choice. Metal is the serious alternative, and the case for it differs by region.
Western Washington: the moss argument
Asphalt roofs west of the Cascades typically last 20 to 25 years, which is shorter than the national average. The reason is not sun damage — it is moss.
Moss holds moisture against shingles, lifts their edges and channels water sideways under the courses rather than down the slope. Combined with heavy tree canopy across much of King, Pierce and Snohomish counties, it is the single most common reason a roof fails before its warranty period ends.
Metal sheds moss and moisture rather than holding it. That addresses the primary failure mode directly, which is a more meaningful advantage here than a general claim about durability.
Eastern Washington: the snow and ice argument
Spokane, Yakima and the Tri-Cities have no meaningful moss problem. What they have is snow load, freeze-thaw cycling and ice damming.
Metal sheds snow rather than accumulating it, and its smooth surface resists the ice dam formation that plagues asphalt roofs at the eaves. Freeze-thaw cycling, which works at every small gap in an asphalt roof over successive winters, has less to attack.
Different problem, same conclusion — with the important caveat that shedding snow onto a walkway, driveway or entrance needs planning rather than being discovered in January.
The honest case for asphalt
It costs substantially less upfront. Every roofer in Washington installs it, so you have the widest choice of contractors and the most competitive pricing. Repairs are simple and materials are universally available.
Algae-resistant grades, which use copper or zinc granules to inhibit growth, are worth specifying in Western Washington and are usually a modest upgrade. That closes part of the longevity gap for a small fraction of the cost difference.
And a 20 to 25 year roof is not a short roof. If you are unlikely to still own the house in 2050, buying a roof that lasts until 2075 is buying something you will not use.
What actually decides it
How long you are staying. The single most important factor. Metal’s advantage is realised over decades.
Your tree cover. Heavy canopy shortens asphalt life considerably and strengthens the metal case.
Your roof’s complexity. Metal on a simple gable is straightforward. On a heavily cut-up roof with many penetrations it is more demanding and the cost gap widens.
Installer availability. Metal requires different skills. Fewer contractors do it well, which matters more than the material choice itself — a poorly installed metal roof is worse than a well-installed asphalt one.
The noise question
Homeowners frequently ask about rain noise. On a roof installed over solid decking with proper underlayment and insulation below, this is far less of an issue than the reputation suggests. It is a genuine consideration on an uninsulated structure such as a barn or carport.