Coastal Security Gates and Bars: Rust Protection by Zone

Updated September 2026 by Meghan Ristea, Procurement Manager.

Within 500 metres of the sea, buy aluminium: the Alu-Deluxe Trellis Door and Alu-Deluxe Fixture do not rust and carry a ten-year manufacturing warranty. In coastal suburbs further back, hot-dip galvanised and powder-coated steel or aluminium. Robo Door writes the corrosion zone and exposure onto every quotation, and the rust warranty follows from them.

Where you stand: coastal suburb or seafront

We rate a site as a coastal suburb when it is within the coastal influence but more than 500 metres from the ocean or tidal water: most of Cape Town, Durban and the suburbs of Gqeberha. Seafront means within 500 metres of the sea, a harbour or a tidal estuary. Exposure adds a second rating: sheltered, semi-exposed, or fully exposed to rain, spray and sprinklers. A beachfront flat's sea-facing balcony is seafront and fully exposed. The same building's courtyard door under a roof is seafront and sheltered. Both go on the quotation.

What the rust warranty looks like at the coast

Zone and exposure	Hot-dip galvanised and powder coated	Electroplated and powder coated
Coastal suburb, sheltered or semi-exposed	5 years	3 years
Coastal suburb, fully exposed	3 years	2 years
Within 500 m of the sea, sheltered or semi-exposed	3 years	1 year
Within 500 m of the sea, fully exposed	2 years	6 months

Compare that with inland sites, where hot-dip galvanised steel carries up to ten years. The sea shortens every steel warranty, which is why aluminium wins as you get closer to it. The paint warranty is a separate cover and does not change with distance from the sea: five years on electroplated or galvanised steel when sheltered, three years fully exposed.

Product by product at the coast

Opening	Coastal suburb	Within 500 m of the sea	Manufacturing warranty
Patio slider	Alu-Deluxe Trellis Door, or Deluxe, hot-dip galvanised	Alu-Deluxe Trellis Door	10 years both; Break-In Repair Guarantee on Deluxe only
Windows	Alu-Deluxe Fixture, or Deluxe Fixture, hot-dip galvanised; Robo Clear	Alu-Deluxe Fixture or Alu-Deluxe Fixture Lite	10 years; Robo Clear 5 years
Front and side doors	Swing Trellis Door (hinged burglar door), hot-dip galvanised	Swing Trellis Door, hot-dip galvanised and inspected yearly	Swing Trellis Door 5 years
Driveway	Sliding or Swing Driveway Gate, hot-dip galvanised	Galvanised steel gate with the hinge weld note, or aluminium gate and fencing	2 years; motor on its own terms
Boundary	Palisade or Clearview, hot-dip galvanised	Aluminium fencing	2 years
Balustrades and railings	Aluminium, or hot-dip galvanised steel	Aluminium	Steel and aluminium balustrades 2 years
Garage	Aluminium Garage Door	Aluminium Garage Door	1 year on door and motor

The aluminium products

Alu-Deluxe Trellis Door, Alu-Deluxe Fixture Burglar Bars and Alu-Deluxe Fixture Lite, all with a ten-year manufacturing warranty, plus aluminium fencing, balustrades, railings, staircases and the Aluminium Garage Door. Aluminium is powder coated for colour, not for rust protection. It can still pit where salt is trapped or where it touches steel fasteners, so Robo Door specifies isolated fixings.

The hinge weld detail

Hinges cannot be hot-dip galvanised because the zinc seizes the bearing surfaces. On a galvanised steel gate they are welded on afterwards, the weld burns off the zinc around it, and that zone is protected with zinc-rich cold-galvanise paint. It is less durable than the original coating, it is excluded from the rust warranty, and at the coast it needs a yearly inspection and touch-up. Robo Door tells you this before you buy rather than after.

Salt, wind and sprinklers

Salt arrives on the wind and settles on every horizontal surface, and it is the salt sitting on the metal between rains that does the damage. Sea-facing and wind-facing openings corrode faster than the lee side of the same house. Garden sprinklers add borehole or municipal water with its own minerals, and a gate that stands in the spray pattern is fully exposed whatever the suburb. Tell the site visit which openings face the sea and which get watered.

Maintenance at the coast

Our terms ask for a wash with mild soapy water at least twice a year; on the coast, more often is better. Rinse off salt after storms. Touch up chips within 30 days. For fully exposed installations at the coast, an annual professional inspection is recommended. Undisclosed coastal location is a warranty exclusion, so tell the quoting team exactly where the property is.

Existing rust on steel bars

Light surface rust on a painted steel product is a chip that was not touched up in time. Clean back to sound metal, apply a zinc-rich primer and a matching topcoat, and the warranty position depends on whether the 30-day touch-up rule was kept. Rust that has lifted the coating across a whole bar is past touch-up; that is the point at which replacing steel with Alu-Deluxe usually costs less than repainting every second year.

Louvre shutters and clear bars

Louvre security shutters in aluminium suit coastal windows and patio doors. Robo Clear polycarbonate bars do not rust, and the product specification rates them for all climate conditions.

What to ask for on a coastal quotation

Product line and material
Zone and exposure assumed for the address
Finish and the paint and rust warranty that follow
Fastener and isolation detail on aluminium
Hinge weld inspection note on galvanised gates
Installation or supply-only scope

Next step

Tell the consultant how far you are from the sea and which openings take sprinkler spray; it decides between aluminium and galvanised steel. Request a free quote, WhatsApp +27 82 888 1919 or call 082 888 1919.