Slope Percentage On Flat Roof

A low slope roof is anywhere from 2 in 12 to 4 in 12.

Slope percentage on flat roof.

The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages. An example for a steep sloped roof is 8 12. Anything more than 9 in 12 is considered steep. What is the standard pitch for a roof.

There are two main categories of roofing. Low slope roofs are from 0 to 3 12 in pitch. Degrees to roof pitch rise in run to see a table. Conventional slope roof range between 4 in 12 and 8 in 12.

Despite the name all flat roofs need to be slightly angled in some direction. Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks. Generally such roofs have a pitch ranging from 1 2 12 to 2 12. Notes to the table above.

There is no standard universal roof pitch roof pitch varies depending on culture climate style and available materials in the usa the range of standard pitches is anywhere between 4 12 and 9 12 in the uk the typical house has a pitch between 40 50 although 45 should be avoided. The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. A flat roof has a slope of 2 in 12 or less. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks.

Although a flat commercial roof is not 100 percent flat. 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. To put it in perspective the angle of this slope would be around 30 degrees. Flat roofs which aren t perfectly flat require a small slope to allow for water runoff.

This means that the rise of the slope goes up or down 8 inches for every 12 inches. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. Some sources consider low slope to include 3 12 pitch roofs. The run always remains constant at 12 inches.

Roofs commonly are built in one of two varieties. Contemporary houses often have flat roofs which shouldn. Most roof s have a pitch in the 4 12 to 9 12 range. The gentle two percent slope is hardly visible but necessary for numerous practical reasons.

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. When it comes time to choose a business property consider the advantages of a flat roof versus those of a sloped roof. The table below shows common roof pitches and the equivalent grade degrees and radians for each. Also see our page quick reference.