Roofing near the coast: what salt air does to your roof

Salt air speeds up corrosion. On a roof near the sea or a bay, the fixings, flashings, gutters and the laps between sheets rust first. Choosing the right grade of steel, fixings to suit, and washing the parts of the roof the rain never reaches all help a coastal roof last.

How salt air damages a roof

Wind carries fine salt off the surf and the bays and leaves it on the roof. Salt holds moisture, and moisture and salt together eat at steel. The damage starts where water and salt sit longest: under the laps between sheets, around fixings, inside gutters and on flashings.

Parts of a roof that rain never washes, like the undersides of eaves and areas under overhangs, often corrode faster than the open roof, because the salt is never rinsed off.

Which parts of the Shire feel it most

The beach and peninsula suburbs, like Cronulla, Kurnell, Greenhills Beach, Woolooware and Burraneer, get the most salt. Homes on Port Hacking, Botany Bay, Gwawley Bay and the Georges River feel it too.

Choosing steel for the coast

Colorbond is made in different grades. BlueScope makes Colorbond Ultra steel for harsher coastal spots and publishes guidance on which product suits which environment. Fixings, flashings and gutters should suit the same conditions as the sheets, or they become the weak point.

Looking after a roof by the water

• Hose down the parts of the roof and gutters the rain never reaches, every few months
• Keep gutters clear, so salty water and leaves do not sit in them
• Watch for rust spots at fixings, laps and gutter joints, and get them looked at early
• After a big storm, check for lifted sheets or flashings

Written by Make It Metal Roofing, a licensed roof plumber in the Sutherland Shire. Updated 4 November 2026.