Metal roofs are great substrates for PM silicone coatings! They last a long time, provide a great substrate for silicone to adhere to, and very rarely need primer. If in good shape, your metal roof will require no primer at all. This is not always the case however.
In cases where rust is affecting the roof, PM’s P-130 Rust Inhibitive Primer is recommended. By applying 1 gallon / 200 square feet, you can almost entirely stop rust in its tracks. Although, there’s nothing that can completely stop rust, P-130 slows it so considerably that it is no longer considered a threat to the roof. P-130 can be sprayed or rolled on and, once dry, it adheres to your silicone coating. It’s a safe and easy way to make sure rust doesn’t take over a nice, metal roof.
Of course, if rust damage has created major holes or gaps in a roof, some panel replacement may be necessary. In most cases, however, P-130 offers enough protection to keep the metal roof’s rust at bay. This combined with PM’s High Solid silicone will offer any metal roof decades of protection.
The only other time a PM primer may be necessary on a metal roof is if Kynar roofing is used. In rare cases, we have seen poor adhesion on Kynar. Thankfully, we have a solution for that as well. Our P-151 primer will coat over Kynar and offer tremendous adhesion for the silicone coating.
For more information on our primers, please reference our primer guide here. If you have specific questions about a roof or would like to see a live demonstration of P-130 over rust, please contact your regional manager.
Please check in next week as we discuss primer usage on spray foam roofing.