What salt actually attacks
Salt in the air settles on every exposed surface of a roof, and it attacks metal fasteners and flashing before it affects the shingle itself. Ordinary galvanized nails and staples can show rust within a handful of years within a mile or two of the water, and once a fastener corrodes, the shingle it was holding loses its grip long before the shingle material itself has worn out.
This is different from the wear pattern seen further inland, where the shingle surface itself, through UV exposure and heat cycling, is usually the first thing to go. Near the water, the hardware often fails first.
Fasteners and flashing that hold up
Stainless steel or hot dipped galvanized ring shank nails resist salt corrosion far better than standard galvanized fasteners, and the added cost is small compared to the labor of a repeat repair a few years later. Flashing follows the same logic. Aluminum and stainless steel flashing outlast standard galvanized steel flashing noticeably in a coastal environment.
Drip edge and gutter hardware get the same treatment on any job within a few miles of the water, since these are the components most exposed to both direct rain and salt laden wind at the same time.
Shingle and metal choices
Algae resistant shingle with copper infused granules holds up better against the dark streaking that shows up on shaded, humid roof slopes across this whole region, salt exposure or not. For metal roofing, aluminum panels are the better choice directly on the water since aluminum does not rust the way coated steel eventually can if the finish gets scratched.
Color choice interacts with heat here too. Lighter colors reflect more summer sun and can keep an attic noticeably cooler through a long Wilmington summer, which matters for cooling costs as much as it does for shingle longevity.
What this means for maintenance
A roof within sight of the water benefits from a closer look at fastener and flashing condition during every inspection, not just the shingle surface. Catching early corrosion on a nail head or a flashing edge is a small fix. Catching it after a shingle has already come loose in a storm is a bigger one.