The best paint for a metal, Inverted Box Rib (IBR) or corrugated iron roof is an acrylic roof coating over the correct anti-rust primer, applied after the roof is derusted and degreased. Prime bare or rusted metal with ZP4 (water-based, ideal for spraying large roofs) or a zinc phosphate primer, then topcoat with Premium Roof & Wall or Shield. A metal roof fails at the primer stage, not the topcoat, so the prep and primer matter most.
What kind of paint do you use on a metal roof?
Use an acrylic roof topcoat over an anti-rust metal primer. The topcoat gives colour, ultraviolet (UV) stability and weather protection; the primer stops rust and grips the metal. A single-coat paint straight onto bare or rusty steel will lift within a season. Premium Roof & Wall is the UV-stable decorative topcoat; Shield adds waterproofing where the roof also leaks.
Do you need to prime a metal roof before painting?
Yes, a metal roof must be primed with an anti-rust primer. Bare and rusted steel corrode under a topcoat without a primer, and old galvanising is too smooth for paint to grip. Prime new ferrous metal with Red Oxide Primer, large roofs with sprayable water-based ZP4, and galvanised sheeting with a high-performance Etch Primer.
The metal roof system, step by step
- Remove rust. Wire-brush or treat rust with Rust Remover, then rinse thoroughly.
- Degrease. Wash off industrial fallout, oil and grease with a degreaser (see the preparation range) and rinse with water.
- Prime. Apply ZP4 or a zinc phosphate primer to the whole roof; use Etch Primer on galvanised sheeting.
- Topcoat. Apply two coats of Premium Roof & Wall, or Shield where the roof needs waterproofing too.
Painting a new metal roof vs an old one
A new metal roof needs the mill oil removed and a primer; an old roof needs the rust and chalk removed first. New galvanised sheeting carries a factory oil film that stops paint bonding — degrease it and use Etch Primer. An old roof needs derusting with Rust Remover and a wash before priming. Either way, the metal must be clean, dry and primed before the topcoat.
IBR vs corrugated iron — does it matter?
The system is the same for IBR and corrugated iron — derust, degrease, prime, topcoat — the difference is only the profile. Corrugated sheeting has more surface area per square metre than flat IBR, so it uses slightly more paint. Work the coating into the troughs and over the fixings, where rust and leaks start.
Galvanised vs new steel
Galvanised sheeting needs an etch primer; new ferrous steel needs a rust-inhibiting primer. Old galvanising is smooth and slightly weathered, so Etch Primer bites into it for adhesion. New bare steel takes Red Oxide Primer. On a large existing roof, sprayable ZP4 covers fastest.
Is there a waterproof paint for a metal roof?
Yes — where a metal roof leaks at laps and fixings, use a waterproofing coat rather than a decorative one. Shield or Fiber Coat seal the surface and flex over the joints. For colour and UV protection on a sound roof, the decorative Premium Roof & Wall is enough.
How long does metal roof paint last?
A primed, two-coat metal roof lasts 7 to 10 years, less where rust returns at fixings and laps. Touch up rust spots early and re-coat before the primer is exposed, and the roof keeps going for years.
Frequently asked questions
What kind of paint do you use on a metal roof? An acrylic roof topcoat over an anti-rust primer — ZP4 or zinc phosphate on the metal, then Premium Roof & Wall or Shield.
Do you have to prime a metal roof? Yes. Bare, rusted or galvanised metal needs the correct primer, or the topcoat lifts.
How do you paint a rusty roof? Remove the rust with Rust Remover, rinse, prime with an anti-rust primer, then apply two topcoats.
Where to buy
Shop ZP4, Premium Roof & Wall and Shield, or read the complete roof paint guide. Trade pricing: +27 84 985 6141.
