Roof Estimating Multiplier

The pitch of the roof is the rise over a 12 inch run.

Roof estimating multiplier.

Divide the rise by the run the run is 12. 100 1 054 105 4ft 2. Accurate roof calculations are achieved using this table and all you need to do is measure the roof width and length and then you are ready to do a roof pitch measurement. For example a 4 12 pitch roof that is 100 square feet.

For roof slopes expressed as x in 12 rise in run the roof pitch multiplier is determined by finding the square root of rise run 1. Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area. For estimating purposes we also assume that there is a chimney a couple of dormers and two layers of old shingles that need to be torn off and removed before a new roof can be installed. 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.

Find the square root of the result. A roof pitch of 4 in 12 4 12 has a rise of 4 and a run of 12. Just multiply the roof width by roof length and then the result should be multiplied by the use of the pitch multiplier. Assuming this is a hip roof we multiply this by 1 1 which gives us roughly 18 squares or 1 800 square feet of the roof surface.

Use our roof pitch calculator to find the pitch of your roof. Roof pitch refers to the measurement of the slope of a roof and you express this as a ratio. The slope of the roof provides the rise and the run to be plugged into the equation. However the end result may be well worth it as your roofing material is estimated to last up to 50 longer and will require less maintenance.

Roof pitch area multipliers. A 12 in 12 roof can cost up to 50 more than a 4 in 12 roof.