Wood or Metal: Which Gate Material Lasts Longer on the Gulf Coast?

Two different ways to fail, not one scoreboard

“Which lasts longer” assumes wood and metal degrade the same way. They don’t. Wood is a moisture story: it swells and shrinks with the weather, and in decay-friendly conditions, fungi attack it — the USDA’s Wood Handbook puts it plainly for this region: “In humid regions, such as the Gulf States, these products often do not air-dry fast enough to avoid losses from fungi” without preservative treatment. Metal is a corrosion story: the coating or alloy itself is the barrier, and once it’s breached — a scratch, a cut edge, a weld — bare metal is exposed to the air. The American Galvanizers Association notes that sea spray and wetting/drying cycles are among the real factors driving how fast that happens.

That means the better question for a Gulf Coast gate isn’t “wood or metal” — it’s “which wood species and treatment” or “which alloy, coating and hardware.”

What Gulf Coast humidity actually does to a wood gate

Wood keeps absorbing and releasing moisture with the air around it, which changes its size. The USDA’s equilibrium moisture content data doesn’t include Galveston or Houston directly, but the nearest Gulf Coast stations — Mobile, AL and New Orleans, LA — sit at roughly 13% to 15% outdoor equilibrium moisture content for most months of the year, barely dipping in winter. The USDA’s own recommended installation moisture content for a “damp, warm coastal area” averages 12%, with individual pieces as low as 9%. A picket installed on the dry side and swelling to the region’s humid-season equilibrium is a real, if small, seasonal movement — and it’s not the same for every species.

Using the Wood Handbook’s own dimensional-change coefficients (Table 13-5) for a 5.5-inch picket moving from 9% to about 14.5% moisture content: loblolly pine moves about 0.08 in, while western redcedar moves about 0.03 in — roughly a third as much. That’s why a cedar gate tends to keep a tighter, more consistent fit at the latch across seasons than a pine one of the same dimensions, independent of the decay-resistance difference between the two species.

What salt air actually does to a metal gate

Aluminum has no iron content, so it doesn’t rust the way steel or wrought iron does — that’s a real, structural difference, already covered in depth on aluminum fencing in hurricane and salt-air areas. Galvanized steel and wrought iron rely on a zinc coating or paint system instead: the AGA notes that atmospheric corrosion rates for galvanized steel “rarely exceed 0.3 mils per year,” but that rate depends on “prevailing wind direction, type and density of corrosive fumes and pollutants, amount of sea spray, number of wetting and drying cycles” — all of which point toward faster consumption of the coating near open water than further inland.

There’s a second risk specific to metal: mixing two different metals at a hinge, fastener or post cap. The AGA’s own electrode-potential table shows zinc, aluminum, steel and stainless each sit at a different electrical potential in seawater; put two of them in contact with a conductive film (sea spray, condensation) between them, and the bigger the gap, the more likely a galvanic reaction at that joint — worse still if a small fastener (the anode) touches a large metal panel (the cathode). The AGA’s fix is simple: an insulating barrier between the two metals, or hardware actually rated for the gate’s alloy.

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