Properly installed, metal roofs will last as long as your house. Sealing out water, surviving high winds and easily shedding snow. Metal is resistant to fire, insects, mildew and rot. Metal roofing is also lightweight, weighing in at about 150 pounds per square whereas shingles can weigh up to 240 pounds per square. Metal increases energy efficiency because it reflects light and heat, lowering your cooling bill. Metal may be more costly, however, you will save money in the long run by never needing to replace your roof.