Ask the Expert Question-and-Answer Archive

by Ron Joseph

February, 2008

Painting Over Sheet Steel Prefinished with Silicone

Q: I purchased a house that has a metal roof prefinished with Akzo 900 silicone modified polyester paint. According to internet sources, "all coil coated paint films have internal additives that do not allow good adhesion". I want to change the color from Farm Green to a charcoal color. Sherwin Williams and ICI do not have recommendations. Is there a way to change the color?

A: Because of the large flat surface you wish to repaint, you run the risk of having a massive paint peeling problem. If you absolutely want to repaint the roof you would need to thoroughly scuff sand the existing coating to a dull finish and remove any oxide that might be present. You could apply a two-part epoxy primer and follow with a roof coating in the color of your choice. The primer MUST be recoated with within 24 hours, because epoxy coatings tend to oxidize quite quickly.

Having given you this recommendation, I don't have confidence that the new coating will last. It might hold up in some areas and peel in others. Frankly, you might be better off living with the existing roof or replacing it.

I'm sorry that the news is not better.

Regards,

Ron Joseph