Slope Percentage On Flat Roof

In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.

Slope percentage on flat roof.

To put it in perspective the angle of this slope would be around 30 degrees. Generally such roofs have a pitch ranging from 1 2 12 to 2 12. Roofs commonly are built in one of two varieties. An example for a steep sloped roof is 8 12.

Most roof s have a pitch in the 4 12 to 9 12 range. The run always remains constant at 12 inches. 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. Degrees to roof pitch rise in run to see a table.

When it comes time to choose a business property consider the advantages of a flat roof versus those of a sloped roof. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. This means that the rise of the slope goes up or down 8 inches for every 12 inches. A flat roof has a slope of 2 in 12 or less.

The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages. Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks. It s just a little math. The table below shows common roof pitches and the equivalent grade degrees and radians for each.

The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. Anything more than 9 in 12 is considered steep. Notes to the table above. Contemporary houses often have flat roofs which shouldn.

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. Some sources consider low slope to include 3 12 pitch roofs. Although a flat commercial roof is not 100 percent flat. Conventional slope roof range between 4 in 12 and 8 in 12.

Also see our page quick reference. Flat roofs which aren t perfectly flat require a small slope to allow for water runoff. What is the standard pitch for a roof. There are two main categories of roofing.

Despite the name all flat roofs need to be slightly angled in some direction. See below after the table for directions on how to convert any roof slope from one form to another even roof slopes not shown in the table. 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. Low slope roofs are from 0 to 3 12 in pitch.