After my fireplace (Megamaster) was installed, the roof started leaking slightly and the water would run down the
outside of the chimney and, depending on how much rain there was, down the rest of the fireplace. Initially I sanded
down (very well) all the areas I could see had rusted and applied a rust converter to these areas, making sure it got
into all of the cracks, and then I sprayed high heat paint over these places.
I tried to see where the water was getting in (even simulating rain with the hose) and used acrylic waterproofing and membrane to seal all around the outside of the chimney where it entered the roof. The roof is corrugated iron, so I also filled up the channels heading straight for the chimney with small bags of sand and applied membrane over this to make sure everything was watertight.
It seemed fine as long as it didn’t rain, but with the first rains the leaking was back. This time I sanded everything down again, applied rust converter and bought a litre of high heat paint. Following the instructions to the letter, I applied the paint with a brush, paying extra attention to any places that rust could start from. I painted the roof with the recommended roof paint, being sure to prime it properly first. I then wet it with the hose and it didn’t leak! I was happy that I had handled the problem.
Unfortunately, even though the roof was not leaking anymore, the chimney and rest of the fireplace kept on rusting in the places where previous rust had been. I contacted the customer service manager at Megamaster, but it seems that they don’t really have any helpful suggestions. It is my opinion that they have not encountered a problem like this before.
I would be grateful for any suggestions regarding this matter. I believe a fireplace is an excellent way of taking the load off our already strained electricity grid. I have attached a couple of photos showing the rust.
Linda Thomas, by email
Daniel Fonnie, technical advisor at Duram Products, advises: Anti-rust coatings can only handle between 40-60˚C, whereas the heat from a chimney and/or fireplace is up to 250 ˚C, depending on the type of fire. The only alternative is to strip/sand the rusted areas (sandblasting is an excellent option), then thoroughly wash down the surface using NS2 Duram Galvanised Iron Cleaner, which removes oxidation, dirt and impurities from weathered metal and etches the surface for maximum adhesion of paint. Rinse the surface well with water to remove all traces of degreaser/cleaner. Immediately, or when the surface is completely dry – keep checking the surface regularly – usually within one hour (to avoid flash rust), apply NS7 Duram Heat Resistant Paint directly to the affected areas. NS7 can handle heat temperatures up to 700˚C. This heat resistant paint can only be applied directly onto clean, rust-free, bare metal surfaces. NS7 should definitely not be applied to surfaces coated with primer, paint or anti-rust products.
For further assistance email Daniel Fonnie at or contact the Technical Helpline on 0800-500-222