Knowledge Center / How to Take a Roof Pitch
For new technicians, measuring a roof pitch can be a little daunting. A slight miscalculation in pitch can make a huge difference when working on a roof. For example when placing a stand that is 4' long, a ¼” mistake in your pitch means a 1” mistake on the roof. If you take your time however, you’ll find that taking a roof pitch is a snap. The best way to determine roof pitch is as follows:
You will need:
- Place one end of your level on the roof deck as close as possible to the install location.
- Position the level so that the bubble reads level.
- At the end of the level on the down slope side, measure straight down from the bottom of the level to the roof deck.
- Divide that measurement by the length of the level. In the illustration below, we have a 1’ level and 4” from the bottom of the level to the roof. This means we have a 4/12 roof pitch. In other words for every 12” out, the roof drops 4 inches. When using a longer level, divide the measurement to the roof deck by the length of the level. For example, let’s say that in the diagram below we had used a 4’ level and the measurement to the roof deck is 16”. 16 divided by 4 equals 4. Again, we have a 4/12 pitch.
Tips:
- Try to use a longer level for truer measurements.
- Take pitch readings from several spots to make sure you get the same readings.
- Newer homes use factory built trusses and, as such, tend to be more precise (i.e. 4/12, 5/12, etc.). Older homes had rafters, built on site. Though not as common, it is not entirely unusual for older homes to have odd pitches such as, say 3 ½ on 12.

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