Why is it important to know the roof pitch?
Determining the roof pitch is very important when giving roof estimates, it directly affects all parts of the estimate. The steeper the pitch the more the costs go up. For instance: In roof Tear-Offs, Loading the Roof, and Applying the Roof, the cost will increase as the roof pitch gets steeper.
Correctly determining the roof pitch, prior to figuring out the roofing estimate is critical in figuring out a precise and accurate roof estimate.
Note: Many roofs have more than 1 pitch so you must determine the number of squares per the different roof pitches.
How to determine the Roof Pitch.
You need to determine how many inches the roof rises for every 12″ it runs or spans.
Simply place a level across the top ridge with the 12″ mark resting directly on the center top of the ridge, and make sure the level is level. Now take a measurement from the surface of the roof to the bottom of the level, however many inches that read is the roof pitch. For instance: If your tape measure reads 6″ then the roof pitch is 6/12, if your tape measure reads 8″ then the roof pitch is 8/12 etc. If there are existing roof layers you will need to allow for these, try and determine how thick those layers of roof protrude above the roof sheathing and add this amount to the tape measurement reading. For instance: If the roof layers protrude above the roof 1″, simply add 1″, so if your tape measurement read 6″ you would add 1″ which equals 7″ or 7/12.
You can also determine the roof pitch from a ladder without having to get on the roof. From the bottom of a rafter tail or at a barge rafter at the gable end on the overhangs of the roof, the procedure will be the same. This way is more accurate because there are no layers of roofing to compensate for.
The pitch factor will get multiplied by the total amount of squares, each roof pitch has its own pitch factor as shown in the chart below. Hips, Rakes, and Valleys also use the same pitch factor.
Pitch Factor
Simply enter in your measurements or enter in the whole amount of roof squares at one time. Choose the roof pitch and the Roof Estimator will automatically multiply the amount squares by the roof pitch factor, to give you the correct amount squares. When measuring from blueprints you need to take into consideration the roof pitch, since blueprints have no rise/pitch, you’re blueprints will have the correct roof pitch noted on them. The same goes for Hips, Rakes, and Valleys. We’ve also included a % waste box that will allow for any waste for cut-up roofs with lots of hips and valleys. View the Pitch Factor screenshot below
Pitch Factor Chart
| Roof Pitch | Pitch Factor (Gets Multiplied by Total Sqs.) |
|---|---|
| 2/12 | 1.01 |
| 3/12 | 1.03 |
| 4/12 | 1.05 |
| 5/12 | 1.08 |
| 6/12 | 1.12 |
| 7/12 | 1.16 |
| 8/12 | 1.20 |
| 9/12 | 1.25 |
| 10/12 | 1.30 |
| 12/12 | 1.41 |
| 14/12 | 1.54 |
| 16/12 | 1.67 |
| 18/12 | 1.80 |
| 20/12 | 1.94 |
| 22/12 | 2.09 |
| 24/12 | 2.24 |
