Rusty Metal Roof: What To Do
If you have a rusty metal roof, you need to remove the rust, then keep it from coming back. You can choose to remove metal roof rust yourself or hire a professional. Likewise, prevent the return of metal roof rust with either a DIY paint job or a professional coating. A trusted professional is more likely to provide a complete, attractive and lasting solution to your rusty metal roof, but a DIY job will, of course, save money.
Get Rid of Metal Roof Rust
Most of the time, not every speck of rust needs to be removed before recoating a rusted metal roof. Instead, use a heavy power washer or a light sand blaster to blast away all the loose, flaking rust. The water or sand will also remove dirt, mildew and flaking paint from the surface. For stubborn metal roof rust that somehow survives a power blasting, try Trisodium Phosphate (TSP).
You could rent a power washer or sand blaster, but using either of them on your roof tends to be dangerous work, and you may not get at all the metal roof rust that needs to be removed. It may be worth the cost to hire a professional to blast away at your rusty metal roof. If you work with pros, make sure they also use chemical solutions to remove and block any mildew on the roof.
Keep the Rust from Returning
Of course, you will probably just have a rusty metal roof again in a few months if you don’t coat the metal. Again, you have the option of painting the roof yourself or having a contractor paint the roof or add a specialized coating.
If you opt for a DIY paint job, wash and rinse the roof thoroughly and let it dry. Start painting with a zinc primer, which can help prevent metal roof rust. Specialized metal roof paints are available for the top coat. Still, you may need to repaint the roof every few years to prevent the revenge of the metal roof rust.
The other option is an acrylic coating. Most of these coatings leave a metallic finish, but they will successfully block out metal roof rust for up to 10 years.
Updated January 22, 2018.