Great question. In a coastal, salty-air environment, I usually tell customers to expect a 10–15 year service life from our standard powder-coated steel urban benches with basic outdoor bench maintenance. That assumes you are not directly on a pier with constant salt spray, and you occasionally rinse the frame with fresh water.
If you want a bench that really holds up on a seafront promenade, specify marine-grade materials. Our powder-coated aluminum benches with 316 stainless steel fasteners and composite or high-density timber slats typically last 15–25 years before they need major refinishing. The salty air corrosion resistance comes from sealed welds, an epoxy primer under the powder coat, and non-absorbent slats that do not trap moisture against the frame.
The biggest mistakes I see are selecting mild steel in a coastal setting and ignoring small coating chips. Salt air gets into those scratches, rust starts, and the finish fails early. A quick freshwater rinse every few weeks and touching up chips will extend coastal street furniture lifespan more than most people expect.
So the short answer is a coastal urban bench lifespan of about 10–15 years for standard powder-coated steel designs, and 15–25+ years for marine-grade powder-coated aluminum or stainless benches with light outdoor maintenance.