Roof System Types
The slope of a roof is often referred to as the pitch. The slope, or pitch, of the roof is determined by the vertical rise in inches for every horizontal twelve inch (12″) length (called the “run”). A roof with x rise/12 run slope means that for every 12 inches horizontally (run), it rises x inches.
Generally, roofing types and roofing products are typically divided up into two primary categories, steep slope roofing and low slope roofing. Sometimes steep slope roofing is also referred to as “residential roofing” due to the fact that most single family homes in the U.S. are constructed with some sort of pitch or slope to the roof. Just as steep slope roofing is often referred to as residential roofing, the term low slope roofing is oftentimes synonymous with “commercial roofing”. Again, this is due to the fact that, predominantly, commercial buildings have “flat” roof designs.
If we were to classify roofing slopes more specifically, the list below contains the common roof slopes and the terms which classify them. However, in general terms, low slope roofs (commercial roofs) are those below 2/12 or 3/12 while steep slope roofing would consists of roof pitches above either 2/12 or 3/12 and higher.
Classifications of low slope roof membranes or systems:
- Built-up roof (BUR) membranes
- Metal panel roof systems for low-slope applications
- Polymer-modified bitumen sheet membranes