How Much Slope For A Flat Roof

Most roof s have a pitch in the 4 12 to 9 12 range.

How much slope for a flat roof.

A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof. This is necessary for allowing water to run off of the epdm membrane surface and towards an appropriate drainage system but this slope doesn t need to be extremely steep and when covering a large property the angle of the flat roof can be near invisible to the naked eye. The slope of your roof is the angle at which it inclines or declines. This is the basis for calculating the angle which is approximately a 1 19 degree slope.

In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. If you imagine the top of a building to be the base of a triangle and the peak of the roof to be the triangle s highest point the slope of the roof is the line that connects them together. Generally such roofs have a pitch ranging from 1 2 12 to 2 12. Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks.

The table below shows common roof pitches and the equivalent grade degrees and radians for each. Despite the name all flat roofs need to be slightly angled in some direction.