How To Repair Rusty Metal Roof

DIY specialist and home improver Natasha Dickins from Little Red Industries shows how to get handy with a quick repair of rust damage on a metal roof.

My area was recently hit with extreme weather for nearly a fortnight. High winds and heavy rains resulted in a dripping water feature from the dining room ceiling, but the constant storms meant there weren’t many opportunities to get up a ladder and fix the leak.

I waited for dry spells to treat the rusty sections on my corrugated ColorBond roof. The third repair finally covered the patch that was letting in water.

I followed a simple three-part system using layers of flexible waterproofing solutions, with products with high adhesion properties that can also withstand UV exposure and heat.

First, I treated the rust with Bondall’s Ranex Rustbuster to prevent it from spreading. Then I used Gripset Betta Waterproof Peel & Seal Tape as a flashing to seal the damaged area, and coated it with Gripset Betta Bitumen Rubber that forms a flexible waterproof membrane.

TIP Each patch-up was done and dry in just a couple of hours, although I recommend following the dry-times on the packaging.


I looked for rusty holes and metal panel edges that had lifted slightly. It took a few patch-ups before sealing the one that stopped the leak.

TIP Treating a small section of rust doesn’t mean there won’t be more corrosion and this isn’t a guaranteed long-term solution for a deteriorating roof.

I popped on eye protection, mask and gloves, then I used a wire brush to remove any loose debris, sweeping it away with a soft brush and wiping over with a damp cloth.

TIP I stood on a securely positioned ladder to work on this patch near the edge of my roof. Avoid going onto your roof without checking you have the proper safety equipment.

To prevent the rust from spreading further, I coated the damaged area with Bondall Ranex Rustbuster, slowly pouring while using a cloth to contain and dab it to saturate the metal.

TIP Have a few cloths on hand to wipe the excess from non-rusty surrounding areas, then leave it to work its magic while drying out completely.

Using scissors, I cut pieces of self-adhesive, tear-resistant Gripset Betta Waterproof Peel & Seal Tape to run along the corrugations, overlapping the edges by about 3mm and extending the ends past the rust by about 20mm. I cut an extra piece to run over the ends horizontally to ensure they were totally sealed.

TIP Press the tape down to remove air pockets and creases and run along the edges to ensure they’re adhered.

To apply the tape, I pulled the paper back about 30mm and positioned it with the tacky, exposed rubber facing down. Then I slowly pulled the paper back when pressing the tape to remove any air bubbles. Don’t pull off the full length before sticking it down.

TIP I found this little trick helpful when working on a long patch. Cut a sliver from the end (or use masking tape) to stick across the paper to keep the two pieces together while pulling it back.

I sealed over the tape with a coat of Gripset Betta Bitumen Rubber, working it past the edges of the tape, covering the brush with plastic wrap to prevent it from drying out between coats, and leaving to dry for about an hour.

TIP This product has a surprisingly low odour, with a lovely consistency that brushes on easily. Use a nylon brush and wear gloves as it takes a bit of scrubbing to remove from skin.

I applied a second coat, double-checking the bitumen covered the joins and was evenly coated over bumps or raised sections and left it to dry throughly.

TIP To wash up, rinse the brush immediately in water then soak in Bondall Waterbased Turps, or wrap and dispose of the brush responsibly.

I didn’t have much time to get these patched up between downpours, but look how well the membrane has cured, even with challenging dry-times. It worked a treat, and the roof is no longer leaking.

Have you done a waterproofed patch up? Post your project on Facebook and Instagram, tagging, @monocel.timbercare and @littleredindustries – we love to see your solutions!





Unit 2, 115 Belmont Avenue
Belmont 6104
Western Australia

Phone: (08) 6272 3800
Fax: (08) 9277 4068