Residential metal roofing is primarily made of steel or aluminum. Metal roofing for residential applications is very lightweight with the heaviest product weighing about 1.5 pounds per square foot when installed.
Architectural roofing shingles are among the highest quality roofing products made. Traditionally, they are composed of a heavy fiber glass mat base and ceramic-coated mineral granules that are tightly embedded in carefully refined, water-resistant asphalt.
Low-slope roofs, more commonly referred to as flat roofs, come in a variety of system types. Low-slope roofs are available in Modified Bitumen and Single Ply systems. Each system type has it's place. The decision on which system to use should be based more on the use of the building, and not primarily on initial cost.