Metal roofs are often associated with sheds, barns or houses in cold climates because slick metal sheds snow and ice more efficiently than shingles. Many of these roofs have steep pitches, which are more effective at shedding snow and ice. But you can use metal roofing on low-slope roofs, generally defined as those which rise 3 inches or less per foot. They are subject to the same weight or load calculations as other roofs but metal roofing can last up to 40 years.
Metal roofing has been used for years in commercial and industrial low-slope roof applications. It generally has a longer lifespan than other roofing materials, because it is not subject to decay and degradation from moisture. Metal also resists heat and can help make buildings cooler. It also is generally less expensive to install, because most applications do not require wood decking or other sub-strates. Metal roofing also is completely recyclable.
The preferred style of low-slope metal roofing is called standing seam, which makes joints water-tight. This style has vertical seams which interlock adjacent panels, in a fashion similar to tongue-and-groove wood interlocking. Some low-slope metal roofing systems employ machine-seaming--a device is rolled along the seams to crimp them firmly together.
Metal Is Lighter
Metal roofs are much lighter than other roofing materials, placing less strain on the basic framing structure of the building. A typical metal low slope roof will vary in weight from 40 to 135 pounds per hundred square feet, the lightest weights of any roofing materials. They also can be applied directly over roof joists or support, without any underlying solid wood decking which adds weight to the roof.
Aluminum or Steel
Aluminum and steel are the most common roofing metals, although copper may be used in some applications. Both aluminum and steel are available in many styles of corrugations, with the width and height of the ridges and valleys varying. The thickness of the metal also will vary according to the expected loads on the roof. Most metal roofing is available in a variety of colors with some type of protective coating to resist corrosion.