Flat roofs which aren t perfectly flat require a small slope to allow for water runoff.
Slope percentage on flat roof.
Conventional slope roof range between 4 in 12 and 8 in 12.
Low slope roofs are from 0 to 3 12 in pitch.
If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks.
There are two main categories of roofing.
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.
The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages.
What is the standard pitch for a roof.
A flat roof has a slope of 2 in 12 or less.
Contemporary houses often have flat roofs which shouldn.
Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks.
The gentle two percent slope is hardly visible but necessary for numerous practical reasons.
It s just a little math.
Despite the name all flat roofs need to be slightly angled in some direction.
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.
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.
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.
Most roof s have a pitch in the 4 12 to 9 12 range.
Anything more than 9 in 12 is considered steep.
An example for a steep sloped roof is 8 12.
Degrees to roof pitch rise in run to see a table.
Also see our page quick reference.
Roofs commonly are built in one of two varieties.
A low slope roof is anywhere from 2 in 12 to 4 in 12.
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.
The run always remains constant at 12 inches.
Some sources consider low slope to include 3 12 pitch roofs.
To put it in perspective the angle of this slope would be around 30 degrees.
The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches.
Generally such roofs have a pitch ranging from 1 2 12 to 2 12.
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.
Notes to the table above.
