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.
The cost to install the metal roof in a picture above, was about $1300 per square. Cost of Steel Standing Seam ranges from $800-1000 for a simple gable roof. As soon as the roof becomes more complicated, the price goes up to $1200-1500 range.