Aluminum vs Wrought Iron vs Wood: Which Gate Lasts Longer

How each material actually fails outdoors

Aluminum does not rust. It oxidizes, and that is the point: the oxide film forms almost instantly and blocks further attack on itself. That is metallurgy, true of any aluminum. It is not immunity. Chlorides pit aluminum, a wet joint with a steel fastener corrodes galvanically, and on a finished gate the look is carried by the coating, not the metal.

Steel and wrought iron rust, and rust does not self-limit. The oxide is porous, it lifts, it exposes fresh metal, and the section keeps thinning. Paint is the only barrier, so an iron gate is a repainting schedule shaped like a gate. The weak points are predictable: welds, joints that hold water, picket bottoms, the buried part of the post.

Wood has no corrosion problem. It has a water problem. It swells and shrinks, joints work loose, fasteners elongate their holes, and decay starts at end grain and wherever wood meets soil — long before the middle of a board gives up.

Aluminum's real weakness: filiform corrosion

Filiform corrosion is the failure mode nobody selling aluminum gates volunteers. It runs under an organic coating and starts at a break in the film: a scratch from installation, a hole drilled on site for a lock or hinge, a cut end, an impact in transit. From there, fine threads creep sideways under the coating, like worm tracks. Warm humid air makes it worse. Salt makes it worse than that.

The honest scale: it rarely eats through a frame. It attacks the bond between coating and metal, so you lose the finish, not the structure — small comfort, because the finish was the reason to choose aluminum. Two things control it. The first is pretreatment before the powder goes on; powder over a badly prepared surface is a coating waiting to lift. Pretreatment is one of the six steps we run in-house, with cutting, welding, grinding, assembly and spraying, and our powder is TIGER Coatings from Austria at 80–100 µm.

The second control is yours, not ours. Do not drill a coated frame unless you have to; if you must, deburr and seal the hole. Touch up scratches when they happen, and wash salt off near the coast. Our own figures — color held 10 to 15 years, welded 6063-T5 structure 30 years without corrosion or rust-through (that is the expected life of the alloy and the weld, not a record we have watched run out — the works dates to 2005) — assume the film stays intact. Test reports from a Chinese domestic third-party institute exist and we will send them; read them as a supplier's evidence, not a guarantee. Touch-up paint never matches powder, and a real repair means stripping and re-baking.

Aluminum is softer than steel — what that costs you in span

Aluminum is softer than steel and flexes more. The same profile shape bends further under the same load and dents where steel would only scuff. On a gate that shows up as sag at the latch edge of a long leaf, and as damage from a bumper or a wheelbarrow.

That is a design problem, not a disqualification. The fix is section: thicker wall, deeper frame members, internal reinforcement, hinges and posts sized for the leaf. Our gate frames use 3.0 mm wall profile — a gate-frame number, not a fence or railing number. The two get quoted interchangeably in a way that flatters a spec sheet. Ask which one you are being handed.

We do not extrude. We buy primary 6063-T5 profile from Anhui Guangyin Aluminium, a state-owned brand, and from Jiangxi Huike. The largest single leaf we will make is 7 × 4 m — a ceiling, not a recommendation. Anything past shipping size gets broken up and joined on site, so plan for a joint line and someone competent to make it.

What wrought iron still does better

Mass, first. A heavy steel gate closes with a thud, and weight reads as security whether or not it is. Aluminum cannot fake that. Then repairability, the strongest argument for iron: almost any local shop can cut, weld, grind and repaint steel. A truck bends a picket, someone straightens and paints it, done in a morning. Aluminum welds too, but it needs the right process and a steadier hand, and the repair destroys the coating around it.

Forged detail is real as well — hot-worked scroll and hammer marks look like what they are. The bill: repainting forever, heavier posts and foundations, heavier hardware, a bigger operator on an automated gate, and rust starting at the welds and the base while nobody is watching.

When is wood still the right choice?

Wood suits sheltered pedestrian and garden gates, a look neither metal gives you, and owners who want a material that ages visibly rather than one that stays new. Repairs are local and cheap, and boards can be replaced one at a time.

It asks for things back: a gap off the ground, sealed end grain, a refinishing schedule, hardware you can re-tighten, and acceptance that the gate moves with the seasons and may drag in a wet month. It is the wrong answer for an automated driveway gate, for unattended coastal exposure, and for anyone who says no maintenance and means it.

Which material for which site?

Coastal, humid, and nobody will maintain it: aluminum, with real pretreatment behind the coating and a standing rule that site damage gets touched up. A long driveway span on an automatic operator, where every kilogram loads the motor and the posts: aluminum again, sized for the span rather than copied from a fence spec. A period property, a heavy feel, a welder within driving distance, an owner who will repaint: wrought iron. A sheltered garden gate on a modest budget: wood. Aluminum wins the low-maintenance case by default, not by virtue — its failure mode is simply cosmetic.

Questions worth asking any supplier, us included. What alloy and temper, and who extruded it? What wall thickness at the gate frame, and is that number for the gate or the fence? Which powder, at what film thickness? What pretreatment? Welded or bolted? Who reinforces the span? What test reports exist, and who issued them?

Our end of it. Custom gates run ¥800–2,000 per m², roughly US$110–280 at ¥7.2 to the dollar. There is no minimum order; a single gate can ship on its own, and several series can share a container. Freight for one gate to Europe or Australia can run about 60% of the goods value, which sometimes settles the question before the material does. We sign one dealer per country, but only against a signed contract; in markets where no contract is signed, we sell direct to end customers. We started making aluminum gates in 2016 and first exported in 2020 — a short record, and worth weighing as such.