 Understanding the Terms Relating to Roof Pitch Wade Warren June 21, 2022

There's the rise, run, slope, span, and pitch. What does each of these hard-to-understand roof terms mean? Learn them to know how to figure out a roof pitch. What is Rise?

The term "rise" refers to the vertical difference between two places. It refers to how something improves from point A to point B. And in the roofing industry, the rise is a measurement you will use regardless of whether you are calculating pitch or slope. This is because rise is the vertical distance added to the slope or pitch. Rise is the initial number in both pitch fraction and slope ratio, which represent the pitch or slope of any particular roof. Both of these ratios begin with one.

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What is Run?

The term "run" refers to the horizontal change between two locations in mathematics. It refers to the amount that the distance between point A and point B varies. In roofing, the term "run" refers to the distance that must be traveled from the roof's ridge (or peak) to the roof's edge, directly above the gutter line.

The distinctions between span and run are significant because they impact whether you are calculating the pitch or slope of your roof. This distinction is crucial because it affects the accuracy of your results. To be more precise, the run is the measurement used for calculating slope, while the span is the measurement used for calculating pitch.

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What is Span?

A roof's end-to-end measurement is referred to as its span.

In most cases, it is presented in feet, and the measurement may be computed using a tape measure that is 100 feet long. Because it provided an overall measurement of the length of the roof in feet, the span used to be a more relevant roof measurement than it is now. However, this has changed. However, as the complexity of houses increases, so do the types of roofs.

For instance, the process of measuring a mansard roof is not nearly as straightforward as the process of measuring a gable roof.

These days, roofs don't go up and down linearly like they used to, and they're often divided into many pieces. Additionally, dormers and home extensions are sometimes tossed for further complicating matters. It is now much more challenging to determine the pitch of your roof using a single measurement for length, which is what used to be a significant advantage of span.

What is Slope?

The precise slope of a roof may be determined by subtracting the run from the rise of the roof and expressing the result as a ratio.

For instance, if the roof has a rise of 4 feet for every 12 feet of run, the slope would be written as 4:12, which is also its numerical representation.

What is Pitch?

The calculation for the pitch of a roof is distinct from the calculation for the slope of a roof. Pitch is the ratio of the roof's run to its rise, whereas slope is the opposite and compares the run to the rise. To determine the pitch of an object, divide the rise by the span and represent the resulting value as a fraction. You'll often hear professionals refer to pitch as X higher than Y.

The Differences between Slope and Pitch

Pitch Slope

Divide rise by span Divide rise by run

Form of a fraction Form of a ratio

More often used Rarely used

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