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 Copper is the most expensive metal at $11-$12 a square foot just for the roofing material; with installation it can run $15-$18 and up per square foot, or $25,500-$39,600 for a basic single-story ranch-style house, with the price going up for complex installation work. Installing interlocking steel shingles starts around $3-$7.50 a square foot (for labor and materials), or about $5,100-$16,500 for professional installation on a one-story ranch-style house with a gently sloping roof of 1,700-2,100 square feet.