Register Metal roofing materials beat the conventional roofing materials in a number of ways.
Expected Life Properly installed, a metal roof should last as long as the house, completely sealing out water, surviving high winds, and easily shedding snow. Metal is resistant to fire, mildew, insects, and rot. Warranties vary widely, but most companies strongly back their products for 20 to 50 years.
Weight Compared with tile at 750 pounds per square (an area equal to 100 square feet) or concrete tile at 900 pounds per square, metal roofing is lightweight. Most varieties run from 50 to 150 pounds per square. Some types of metal shingle systems may be applied over one or two existing roofs without the need for tear-off or additional structural support. In fact, if you’re building a house or an addition, you can often downsize or reduce the number of roof support members.
Speed & Ease of Installation Most metal roofing materials come in multi-shingle sections or in sheets. An accomplished contractor can install these quickly. If your roof is stripped off and a storm is on the way, shortening the process by a day or two may prove to be a critical advantage. You can also buy single metal shingles that are relatively easy—though time-intensive—to install. Unlike three-tab asphalt shingles, each piece must be individually placed and nailed.
Fire Resistance Because metal roofs are noncombustible, they’re given a Class A fire rating (the most resistant). Part of a roof’s classification depends on materials beneath the surface that could ignite in intense heat, so some metal roofs applied over an old combustible roof, such as wood shingles, may be rated lower.
Heat Conduction Metal reflects radiant heat from the sun, minimizing mid day heat gain. Though the material itself is low in insulation R-value, many systems utilize a dead-air space between the metal and roof deck to increase energy efficiency.
Minimal Roof Pitch Most metal roofing materials can be installed on gently pitched roofs without danger of leaking. Minimum roof pitch is 3-in-12 (the roof rises 3 inches for each horizontal foot).