A roof protects the top structure of a building from precipitation, sun, wind, and other elements- and it is expected to do so for a long time. Roofs are designed systems that are categorized as either steep-slope or flat/low-slope. 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. Steep-slope roofs shed water and are installed on slopes greater than 3:12. Typical steep-slope roofs are made of shingles.
Flat/low-slope roofs are water and weather-proof membranes on slopes equal and less than 3:12.
Most low-slope roof membranes have three principal components:
Roof membranes are applied as either:
Other important factors in a roofing system include:
North American conventional flat/low-slope roof systems include the: