A flat roof is a roof which is almost level in contrast to the many types of sloped roofs. The slope of a roof is properly known as its pitch and flat roofs have up to approximately 10°.
Flat roofs are an ancient form mostly used in arid climates and allow the roof space to be used as a living space or a living roof. Flat roofs, or "low-slope" roofs, are also commonly found on commercial buildings throughout the world. The U.S.-based National Roofing Contractors Association defines a low-slope roof as having a slope of 3 in 12 (1:4) or less.
Flat roofs in Israel
Flat roof in Los Angeles
Flat roof in Warszawa Centralna railway station in Poland (1975)
Green roof at Prince George's Community College in Largo, Maryland
Roof pitch is the steepness of a roof expressed as a ratio of inch(es) rise per horizontal foot, or as the angle in degrees its surface deviates from the horizontal. A flat roof has a pitch of zero in either instance; all other roofs are pitched.
A roof made of thatch, one of the oldest roofing materials, needs a steep pitch to drain properly
Some types of stone roof have a very restrictive roof pitch, which can lead to leaking
Working on roofs with pitches too steep for safety requires a staging of scaffolding boards secured with roof brackets
A building in the Black Forest of Germany with a pitched roof
