The gentle two percent slope is hardly visible but necessary for numerous practical reasons.
Slope percentage on flat roof.
There are two main categories of roofing.
Roofs commonly are built in one of two varieties.
The table below shows common roof pitches and the equivalent grade degrees and radians for each.
A low slope roof is anywhere from 2 in 12 to 4 in 12.
When it comes time to choose a business property consider the advantages of a flat roof versus those of a sloped roof.
Conventional slope roof range between 4 in 12 and 8 in 12.
Most roof s have a pitch in the 4 12 to 9 12 range.
Anything more than 9 in 12 is considered steep.
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.
Despite the name all flat roofs need to be slightly angled in some direction.
What is the standard pitch for a 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.
Low slope roofs are from 0 to 3 12 in pitch.
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.
Notes to the table above.
To put it in perspective the angle of this slope would be around 30 degrees.
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.
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.
Some sources consider low slope to include 3 12 pitch roofs.
The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches.
Also see our page quick reference.
A flat roof has a slope of 2 in 12 or less.
In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.
This means that the rise of the slope goes up or down 8 inches for every 12 inches.
Generally such roofs have a pitch ranging from 1 2 12 to 2 12.
Although a flat commercial roof is not 100 percent flat.
Degrees to roof pitch rise in run to see a table.
Contemporary houses often have flat roofs which shouldn.
It s just a little math.
Flat roofs which aren t perfectly flat require a small slope to allow for water runoff.
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.
