Technology
Why Cast-Aluminium Doors Win in Coastal and Humid Climates
19 August 2026
Salt air finds every coating flaw in steel. Why cast aluminium keeps its finish for decades on the coast — and what to specify.
Ask a distributor in Lagos, Manila or Dubai what kills doors in their market and the answer is rarely burglars — it is weather. Salt-laden air, monsoon humidity and driven rain attack an entrance every day for decades. Material choice decides whether year ten looks like year one.
For a procurement-ready exposure, materials, finish, hardware and maintenance checklist, see WONLY's coastal corrosion-resistant security door solution.
How Coastal Air Destroys Steel Doors
Steel only survives outdoors through its coating. Every scratch, weld seam, drainage hole and hinge cut-out is a breach — and salt spray turns each breach into a rust site that creeps under the surrounding finish. The result is familiar across coastal markets: bleeding stains at the hinges within two or three years, then swelling, flaking and warranty calls.
Why Cast Aluminium Is Different
- Aluminium does not rust — its oxide layer is self-healing and stable in salt air
- Casting produces deep, sculptural surfaces that hold premium finishes
- Roughly one-third the density of steel — easier handling and less hinge wear
- Near-zero maintenance: washing, not repainting
Security Comes From the System
A cast-aluminium door is not “softer” security — the certified rating comes from the engineered doorset. WONLY pairs the cast-aluminium shell with a honeycomb steel core, 16-bolt four-edge locking and a patented anti-drill cylindrical core, reaching GB 17565 Class A with EN 1634 90-minute fire performance and hurricane-rated wind Class 12 on applicable series — the full coastal threat profile in one construction.
What to Specify for Marine Exposure
- Cast-aluminium or equally corrosion-immune construction for any entrance within salt-air reach
- Stainless or coated hardware rated for marine environments
- Sealed, barrier-free threshold with a drop-seal against driven rain
- A finish warranty that names coastal exposure explicitly
FAQ
How far inland does salt air matter? Corrosion studies commonly show elevated attack within several kilometres of the coast — and humidity extends the risk far beyond it. If the market is tropical or coastal, specify as if every door is exposed.