Rust on an IBR roof: what can be done?
Metal roofs are everywhere in Cape Town, from factories and warehouses to complexes, carports and modern homes. IBR, corrugated and Klip-Lok sheeting is strong and light, but its enemy is rust. IBR roof painting, done at the right time and with the right preparation, stops surface rust from spreading and protects the metal for years.
Most rust can be dealt with if it’s caught early. Surface rust, the orange staining and light spots around fixings and laps, can be treated and painted. Rust that has eaten through the sheet can’t be painted over. At the inspection we tell you which sheets can be treated, which need replacing, and whether painting is still a sensible investment or roof replacement is the better option.
How we treat rust before painting
Preparation is where metal roof painting succeeds or fails. It usually involves:
- Cleaning off dirt, salt deposits and loose material, so the coating bonds to the metal and not to grime.
- Taking rust back. Rust spots are wire-brushed or ground back to firm metal. This is done on metal sheeting only, never on asbestos cement.
- Treating the steel with a rust converter or rust-inhibiting primer, so corrosion doesn’t restart under the new coating.
- Replacing what can’t be saved. Rusted-through sheets are replaced with sheeting suited to the exposure.
- Fixings. Rusted screws are replaced or treated, and washers that no longer seal are renewed. Near the sea, we use fixings suited to coastal conditions.
The coating system
A primer goes on across the roof, followed by the topcoats in your chosen colour. We use Plascon roof coatings, choosing a system that suits the metal, its existing finish and how exposed the building is to salt air and sun. Laps, ribs, sheet ends and fixings get extra attention, because that’s where coatings usually fail first.
Why do metal roofs rust in Cape Town?
Metal roofs rust when water and oxygen reach bare steel, and Cape Town’s weather gives them plenty of chances:
- Salt air. Near the coast, on the Atlantic Seaboard, in Blouberg, on the Southern Peninsula and up the West Coast, the wind carries salt that settles on the roof and holds moisture against the metal. It’s the main reason coastal roofs need attention sooner than inland ones.
- Scratches and cut edges. Every scratch from foot traffic, a dropped tool or a solar installation exposes bare metal, and cut sheet ends are especially vulnerable.
- Fixings. Screws and washers rust and lose their seal, and the rust spreads into the sheet around them.
- Ponding at laps. Water and dirt sit where sheets overlap and at the low ends of the roof, especially on low-pitch roofs and roofs with blocked gutters.
- Sun. Strong summer sun breaks down the factory coating, leaving the metal less protected each year.
Corrugated and Klip-Lok roof painting
The same principles apply to every metal profile, with a few differences.
Corrugated roofs
Corrugated roof painting is common on older homes, outbuildings and industrial sheds. These roofs are often older, with more fixings and laps, so preparation takes careful work, and where several sheets are badly corroded we’ll show you before recommending a coating.
Klip-Lok roofs
Klip-Lok sheets clip onto concealed brackets instead of being screwed through, so there are fewer places for rust to start. Klip-Lok roof painting focuses on cut edges, laps, flashings and areas where debris has held water against the sheet.
Gutters, box gutters and flashings
Rust on a metal roof often goes with tired gutters and box gutters, because water that can’t drain sits against the metal. Leaking or ponding box gutters are fixed through box gutter waterproofing before or alongside the painting. Rusted or undersized gutters can be replaced with Brink or uPVC gutters; see gutters and fascias.
Factories and warehouses
Commercial and industrial clients make up most of our work, and large factory and warehouse roofs in the Northern Suburbs and the Cape Flats industrial areas take a lot of punishment from sun and wind. We paint in sections with agreed working hours and access routes, protect vehicles, stock and equipment below, and use working-at-heights compliant teams, with rope access where scaffolding isn’t practical. Andre or our foreman, Randall, oversees the job. See commercial and industrial roofing.
Body corporates and homes
- Body corporates: an itemised quote trustees can table, with work planned block by block.
- Homeowners: houses, garages and carports painted with the same care as a factory roof, with honest advice on painting versus replacement.
Tiled roof as well?
If part of the building has a tiled roof, we can coat it at the same time. See tiled roof painting, or all roof painting services.
The guarantee
Metal roof painting comes with a two-year workmanship guarantee from Roof Direct, and the paint carries the manufacturer’s guarantee of up to 10 years, depending on the product.
Get a free metal roof painting quote
Request your quote or send photos of the rust on WhatsApp.
