If you live within sight or smell of the ocean, you have probably seen what salt air does to outdoor furniture, car bodies and old window frames. Choosing aluminium windows for coastal homes is a sound decision, but the word “marine grade” gets used loosely, and what it really describes decides how long the finish looks and performs.
This guide explains what sits behind that label and what a coastal specification should include. We have been manufacturing aluminium frames in Perth since 1969, so it is written from the workshop side of the job.
What Does Marine Grade Powder Coating Actually Mean?
Most people assume “marine grade” describes the metal. For window and door frames, it usually does not. Frames are extruded (pushed through a shaped die) from 6000 series alloys, chosen because they extrude cleanly and hold tight tolerances. The magnesium rich 5000 series alloys often called marine grade are sheet and plate products, used for boats and cladding rather than window sections.
So on aluminium windows for coastal homes, marine grade powder coating refers to the finishing system, not the alloy. That system has two layers of protection. The first is pre-treatment, a chemical conversion coating applied to clean bare aluminium so the powder bonds to it and resists corrosion creeping underneath. The second is the powder coat itself, a thermoset polyester or fluoropolymer finish that is baked on. The Australian Standard for architectural powder coating on aluminium is AS 3715, and a genuine coastal finish starts with a coater working to it.
Pre-treatment is the part nobody sees and the part that matters most. A high durability powder over poor pre-treatment will still fail near the coast.
Why Salt Air Attacks Aluminium Window Frames
Aluminium does not rust the way steel does. It forms a thin oxide layer that protects it, but chlorides in salt spray break that layer down and leave white, powdery corrosion and pitting on unprotected metal.
On coated aluminium window frames, the classic coastal failure is filiform corrosion. It starts at a cut edge, a screw hole or a scratch from installation, then travels under the coating as fine threads that lift and blister the finish. It is why cut ends need sealing and why site damage should be touched up rather than ignored.
Two other things catch owners out:
- Sheltered surfaces corrode faster. Frames under eaves, patios and balconies never get rinsed by rain, so salt builds up on them while exposed faces stay cleaner.
- Mixed metals react. Where ordinary steel screws or fittings touch aluminium in salty moisture, galvanic corrosion eats into whichever metal is less noble, usually the aluminium.
How Close to the Coast Do Perth Homes Need Coastal Windows?
There is no single distance that makes a house coastal. Australia’s corrosivity standard, AS 4312, grades sites from C1 (very low) up to CX (extreme, typically surf beach frontage), and the grade depends on exposure, prevailing wind and local conditions as well as distance.
Coating manufacturers apply the same thinking to their own products. One major Australian powder supplier, for example, rates its standard architectural range for sites more than 100 metres from the high tide mark, its super durable range for sites more than 10 metres away, and a fluoropolymer range for anything closer. Specify the wrong class and the finish may fall outside the manufacturer’s cover from day one.
In Perth, the afternoon sea breeze pushes salt spray well inland, so homes several streets back from Cottesloe, City Beach, Scarborough or Mandurah can sit in a harsher zone than the map suggests. Properties along the Swan River estuary, from Mosman Park up to Applecross, deal with salt water too, just in a calmer form. If you can see or hear the water, treat your new windows as coastal windows.
What to Check in a Coastal Window Specification
When you compare quotes for aluminium windows for coastal homes, these details separate a coastal specification from a standard one:
- Coating class matched to the site. Ask which powder range is being used and whether it is rated for your distance from the water.
- Pre-treatment and coater. The frames should be coated to AS 3715 by an applicator the powder manufacturer accredits, since that is usually a condition of the coating warranty.
- Grade 316 stainless steel hardware. Handles, hinges, rollers, fixings and screen mesh in 316 stainless resist tea staining far better than 304 grade near the coast.
- Isolation between metals. Nylon washers, sleeves or tape between stainless fixings and aluminium break the path for galvanic corrosion.
- Sealed cut ends and careful installation. Every cut, drilled hole and scratch is a potential start point for corrosion, so it needs to be sealed or touched up.
- A written care schedule. Coating warranties are conditional on regular washing with fresh water and a mild detergent, and the required frequency increases the closer you are to the sea.
The same rules apply to doors. Bifold doors, sliding door tracks and security screen doors all carry rollers, hinges and mesh that face the same salt load as the frame.
Why Choose Action Glass & Aluminium Near the Coast
We manufacture our own aluminium windows and doors in Perth rather than reselling off the shelf units, so frames are made to suit the property.
- Over 50 years of local experience across homes, shopfronts, schools and industrial buildings
- Work to Australian Standards, including AS 1288 for glass installation
- Guaranteed workmanship on our products and installations
- Sites left clean and safe, with schedules respected
Get a Free Quote for Aluminium Windows in Perth
If you are building or renovating near the coast, tell us how far the property sits from the water when you enquire, so the finish and hardware can be matched to the site from the start. Contact our team for a free, no obligation quote.
