Which Gate Metal Holds Up Best in Coastal Salt Air

A charming house is visible through a beautifully designed wrought iron gate, surrounded by lush greenery.

By the time the grinder cuts through the first seized hinge pin, the tube behind it has usually shown how the gate failed. Along Carlsbad, CA, the marine layer rolls in most mornings and leaves salt on every bare edge, and the recheck intervals metal gate contractor carlsbad nap nanny uses are shorter than most coating sheets say. Salt carried inland from the surf settles as chloride deposits. Those deposits hold moisture against the metal and speed rust wherever the coating is thin or missing.

Wrought iron that is really mild steel

Ornate iron gate framed by palm trees, under blue sky, in Campinas

Most gates sold today as wrought iron are mild steel. Without a protective coating it rusts readily, and the first spots show at weld toes, picket ends and the bottom rail where water sits. Lots near Agua Hedionda Lagoon and Batiquitos Lagoon stay damp longer than lots east of Interstate 5, so the same bare steel fails sooner there.

Galvanized steel and powder coat

Beautiful wrought iron gate opening to a countryside villa in Veneto, Italy during a summer day.

Hot dip galvanizing bonds a zinc layer to the steel. The zinc corrodes first, so it can protect a small scratch by sacrificial action. Galvanized steel still needs upkeep at the coast: rinse it, and check cut edges and every weld, because heat burns the zinc away there. A powder coat over galvanized, often called a duplex system, generally lasts longer than either coating alone. It only bonds to the zinc after proper surface preparation, and skipped prep is why the coat peels in sheets.

Aluminum

Aluminum forms a thin oxide film that protects it, and it does not rust. It can still pit in salty conditions, and it corrodes quickly in wet contact with steel or copper. A swing gate leaf of ordinary width can be built from aluminum when the frame is sized for the load. A wide slide gate or cantilever gate puts far more stress on the frame, so the section size and the weld quality matter more than the metal's name.

Stainless steel

Type 316 stainless contains molybdenum and resists chloride pitting better than type 304. Both can show brown surface staining in salt air when nobody rinses them. A stainless frame near the beach needs a fresh water rinse on a schedule, not just a good grade stamped on the tubing.

Hinges, hardware and hollow tubing

Hinges, fasteners and latches should match the gate metal or be isolated from it. Dissimilar metals in wet, salty conditions form a galvanic cell, and the lesser metal gives way. A stainless bolt through a galvanized bracket, or a steel hinge on an aluminum post, needs a nylon washer or sleeve between them. The same goes for the bracket that carries a gate opener or operator arm on a single swing or dual swing install.

Hollow tube frames should be sealed or allowed to drain. Trapped moisture rusts a steel tube from the inside out, and the outside paint can look sound until the bottom rail goes soft under a screwdriver. A drain hole at the low point of each rail costs a few minutes with a drill and saves a rebuild.