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.
1 Steel roofing costs $3 to $10 per square foot ($4,500 to $15,000). 2  Zinc roofing costs $10 to $15 per square foot ($15,000 to $22,500).  Copper roofing costs $15 to $20 per square foot ($22,500 to $30,000).