How to paint a corrugated roof, and make it last

A corrugated iron roof is common on Lowveld homes, farms and lodges, and it’s one of the best-value paint jobs you can do. Done properly it stops rust, cools the building and lifts the whole property. Done in a hurry it peels within a season. The prep is what separates the two.

1. 1

   Pick the right weather

   Work on a dry day with no rain forecast for the drying window on the tin. Start early and avoid painting steel in the full midday heat, when the surface gets hot enough to flash-dry the paint before it can bond.

2. 2

   Make safety the first job

   A roof is a fall risk. Use proper footwear with grip, a harness where you can anchor one, and never work a roof alone. Walk on the fixing lines over the purlins, not the unsupported centre of the sheet.

3. 3

   Clean the whole roof

   Sweep off leaves and grit, then wash the sheets down to remove dirt, chalk and any lichen or algae. The paint can only grip a clean, sound surface. Let it dry fully before going further.

4. 4

   Deal with the rust

   Wire-brush or sand any rust back to sound metal. Treat remaining rust with a rust converter or a suitable metal primer so it can’t creep on under your new paint. This step is where a lasting job is won or lost.

5. 5

   Prime bare and galvanised metal

   Bare steel and shiny new galvanised sheeting need the correct primer, an etch or galvanised-iron primer, or the topcoat simply won’t hold. Skipping this on a new galv roof is the most common reason roof paint lifts.

6. 6

   Apply the roof paint

   Use a proper roof or metal paint, not a wall paint, and apply two coats. Follow the re-coat time on the tin, and lay it on evenly along the corrugations so you don’t leave thin spots on the ridges.

7. 7

   Mind the details

   Check fixings, overlaps and flashings. These edges rust first and get missed most, so give them proper attention on both coats.

Tell us the size and condition of your roof and we’ll work out the primer, the right roof paint and roughly how much you’ll need, so you buy once and finish the job.