I've been planning on a white pre-painted standing seam steel roof for my new house (e.g., VicWest's VicElite) here in central Ontario. Surprisingly, my general contractor is having trouble finding a supplier that has them pre-painted in white (and not hugely expensive, like Ideal's H-F 20). He suggests I consider unpainted Galvalume on steel instead.

My brief web searches indicate this coating isn't as durable as pre-painted steel, and it corrodes in contact with things like copper piping (solar DHW) and pressure treated wood.

Anyone have any experiences to share on unpainted Galvalume roofs vs prepainted steel? Anyone know of a distributor of white standing seam roofing in Ontario?

Thanks,
...Terry
PS It's a 4:12 roof over an attic with R70 floor insulation

You are looking at galvanized and painted vs bare, unpainted galvalume right?

Right, Jon.

Hi Terry  galvalume is acrylic coated for the roofing industry but is the cheapest compared to painted steel, white is the most efficient color for a cool roof system and also has galvalume + primer and a paint system. Unless you have a huge roof the cost is well worth it painted with a standard kynar finish is the best and will last for many years.

Terry;

in our area galvalume and painted (standard colors) galvalume are the same price

Roofing that I used to sell from a company called "Metal Sales" in Pennsylvania used galvalume under all collored metal we sold. Galvalume is a mix of aluminum and zinc.