How Much Slope For A Flat Roof

The slope of your roof is the angle at which it inclines or declines.

How much slope for 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. Despite the name all flat roofs need to be slightly angled in some direction. 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. It takes the manufacturer s recommendations the unique conditions of the roof as well as the skills and the expertise of the installer to arrive at the right slope.

The table below shows common roof pitches and the equivalent grade degrees and radians for each. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. 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.

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. This is the basis for calculating the angle which is approximately a 1 19 degree slope.