Choosing a roof for your house is one of the most important decisions a homeowner has to make. Selecting a roofing material goes beyond choosing a pleasing texture and color. You need to select the roofing material that's right functionally. If the roof is steep, your options for roofing are nearly limitless. If the roof has a shallow pitch -- about 2/12 -- you'll find that your options are fewer. Good roofing choices will make the difference between a watertight roof and one that quickly fails.
A roof with a 2/12 pitch has 2 inches of vertical drop for every 12 inches of horizontal distance. Simply put, it's a shallow roof. A roof this shallow is likely to be found on a ranch house, a shed dormer or a porch. You won't be able to use slate, clay or concrete tiles, which are loose-fitting and require 4/12 pitch or greater.
Pitch of 2/12 is the minimum required for most asphalt shingle roofing products. The resilient asphalt shingles lie much flatter to the substrate than slate, tile and concrete, which keeps water from being easily blown under them. Increasing their flatness and tightness, many asphalt shingles have a bead of roofing cement that seals them to the shingles underneath, forming a tighter seal. Read product specifications to be certain that the particular product you choose can be used on a 2/12 pitch.
Metal roofing -- steel and copper -- are ideal for shallow-pitched roofs. In fact, a properly installed metal roof can be used on roofs as shallow as 1/2 inch/12 inches, which is almost flat. Long-lasting and old-fashioned, metal roofing is an excellent design choice if most of your house has steeper roof planes that are covered in traditional slate or tile.
A standing seam metal roof is the traditional, but more expensive, metal roofing option. Pre-crimped metal roofing panels are less expensive and also within the skill set of many reputable roofers. Metal roofing is slippery when wet, so consider asphalt shingles if you see a future need for walking on the roof.