Slope gradients are written as y x where y is a single unit in rise and x is the run.
1 8 roof slope.
A roof that rises 8 feet over a 24 foot span was said to have a 1 to 3 pitch.
Either way let s see how you can calculate the slope of a roof without using a roof slope calculator.
The pitch of this roof is 4 8 12.
Measure with a speed square.
This means for every 12 horizontal units the roof must rise a minimum of one fourth vertical unit.
Angle the angle of a roof is the same as the roof s slope except instead of being.
For instance if you travel 3 inches vertically and 3 feet 36 inches horizontally the slope would be 3 36 or 1 12.
Both numbers must use the same units.
If the rise is 4 feet over a 24 foot span then the roof pitch was said to be 1 to 6 the pitch can be expressed numerically as a fraction.
Since this is a flat roof or nearly flat roof.
Minimum roof slope roof pitch r905 9 1.
A roof pitch multiplier also known as a roof pitch factor is a number that when multiplied by the area covered by a sloped roof gives the actual area of the roof.
The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches.
The calculator above can handle much of this math.
The most precise way to find the roof s slope is by measuring it from the underside.
0 pitch 1 00x the roof area.
Coal tar built up roofs however can have a design roof slope of 1 8 12 1 percent but no less.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
Roof pitch calculator results explained.
To put it in perspective the angle of this slope would be around 30 degrees.
This means that the rise of the slope goes up or down 8 inches for every 12 inches.
Access one of the rafters then take the measurement this way.
Measuring the slope from the rafters.
Calculating a slope gradient.
Slope the slope of a roof is represented as x 12 where x is the number of inches in rise for every 12 inches of run this is very useful information for many purposes especially for roof framing the slope sometimes called pitch is calibrated on speed squares.
This is read as a one in twelve slope.
You can go by the measurements taken by walking the roof.
Set the level on the edge of the speed square as shown below then place the heel of the speed square on a rafter or gable edge of the roof.
1 pitch 1 01 2 pitch 1 02 3 pitch 1 03 4 pitch 1 05 5 pitch 1 085 6 pitch 1 12 7 pitch 1 16 8 pitch 1 21 9 pitch 1 25 10 pitch 1 31 11 pitch 1 36 12 pitch 1 42.
The maths behind this number is that it is the square root of rise run 2 1.
An example for a steep sloped roof is 8 12.