How do you treat rust on a metal roof?

[#1]

Rust on a roof can be effectively controlled with mechanical removal and the use of specialised primers.

Start by ensuring all the rust including any loose material is removed by abrading with sandpaper or by using a wire brush. Use Sugar Soap to remove all grease, oil and rust residues, then flush with fresh water and allow to completely dry prior to priming.

Once the rust is removed, you can apply Dulux Precision 1L All Metal Primer. Then when the primer is dry, use Dulux Weathersheild.

For areas where all the rust can't be removed, apply Dulux Metalshield Rust Defence Primer, which is both a primer and rust convertor in one. The primer can be applied over hard to remove rust sections, sealing them off from moisture which will prevent it from continuing to corrode. - MitchellMc

[Nailbag]

This is really good advice. @MitchellMc I wasn’t aware about the defence primer product, which will be very handy to now know for any future rusted metal repair work. 

regards Nailbag.