gallonsquare feet. Other websites say a gallon will cover 400-450 square feet of smooth surface. If you've got a rough textured surface or surfaces which need 2 coats of paint, a gallon will cover about 200 square feet. The above answer may be a general rule of thumb.
Highly rated roofing contractors tell us that asphalt is the most affordable roofing option, followed by wood, tile, metal, and slate. Materials for a metal roof can cost up to $350 to $1,500 per 100 square feet. Angie's List members recently reported paying an average of $12,236 for a metal roof installation.
Copper Roof Installation. By far the most expensive when it comes to metal roof installation, copper metal roofing tops with costs around $12 only for the roofing material. If you want to calculate per square feet, the price including the material and labor can go till $18 and even more than that in some cases.