Roof Slope Formula 3 12

3 12 1 2 12 and 1 4 12.

Roof slope formula 3 12.

The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages. Some sources consider low slope to include 3 12 pitch roofs. Roofers like to express the roof pitch ratio in inches and for simplicity they always use a run of 12 inches. It s just a little math.

If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. If you know the angle of the roof in degrees you can find the roof pitch by converting the angle in degrees to a slope then finding the rise by multiplying the slope by 12. To express a slope of 1 3 as a roof pitch you would multiply by 4 4 to produce 12 in the denominator of the ratio. Image 1 12 to 12 12 roof pitch 7 12 pitch.

Then multiply the slope by 12 to get the rise. Also see our page quick reference. Low slope roofs are from 0 to 3 12 in pitch. 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.

Although there s isn t any standard pitch of a roof used on all kinds of sloped roofs you can determine the range of pitches by using a roof angle calculator and by considering factors like the local climate and roofing materials. Angle the angle of a roof is the same as the roof s slope except instead of being. The 45 degree roofs seen on a frame houses are 12 in 12 but roofs can be even steeper consider the mansard roofs introduced by french second empire architects in the middle of the 1800s. For example if you measure 4 inches the pitch of your roof is 4 12.

Roof pitch calculator results explained. Pitched roofs begin with with slopes greater than 3 in 12. Degrees to roof pitch rise in run to see a table. See low slope roofing.

Slopes greater than 18 12 are found on a frame roofs and some mansard style. This will give you the rise over run or pitch. We included a roof pitch chart below the 7 12 example image and the calculator below that. First find the slope by finding the tangent of the degrees eg.

Simply locate a roof rafter board place the end of the level against the bottom edge and measure from the 12 inch mark vertically to the bottom edge of the rafter. Slope tan degrees. The fraction 4 4 equals 1 so it doesn t change the value of the pitch and it produces a pitch of 4 12. Mansard roofs with nearly vertical faces can boast a pitch of 20 in 12.

The most common slopes are. Metal roof slope is expressed by a ratio indicating the roof pitch which notes the vertical rise of the roof in inches for every 12 inches the roof runs horizontally in other words dividing the vertical rise and its horizontal span.