Roof Pitch and Slope Basics

When we talk about about the differences in residential and commercial roofing, we often look at two different aspects: Materials and Slope. On the blog, you’ll find a couple of posts covering the different materials used in both commercial and residential roofing projects to help you understand the differences, as well as some of the similarities. But, in addition to knowing the materials used in each type of project, it’s important to understand how the pitch and slope of a roof can influence your specific project.

What are slope and pitch?

If you remember taking geometry when you were younger, then you’re probably already a step ahead. Slope and pitch are two ways of describing the same geometric calculation for how much a roof slants. The slope looks specifically at how much a roof rises over a 12 inch distance or run. For example, let’s say you have a low-slope roof. Across 12 inches, the roof rises a total of two inches. The slope would then be described as a 2-in-12 roof.

Pitch is another way to look at a very similar measurement. Pitch is calculated by looking at the total change in height over the total flat distance from the highest point to the lowest point, including any roof overhang. This calculation is always displayed as a reduced fraction. For example, let’s say your run (or flat distance) is a total of 40 feet, and your rise over this total distance is eight feet. This would make your pitch equal to 8/40 or ⅕.

The term “pitch” can easily be confused simply because it has many other meanings, including in the roofing world. For several hundreds of years, pitch referred to the highest point of a roof. It also has been used to describe birds in flight and much, much more.

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What is low-slope or flat roofing?

Often, you’ll hear the term “flat roofing” used to describe many types of commercial roofing projects. Additionally, “low-slope roofing” is commonly used for commercial roofing and some residential roofing projects. But that doesn’t mean these types of roofing have absolutely no slope to them. In fact, if a “flat” roof doesn’t have at least a small slope to it, you would get water pooling in problematic places all across the roof. With water weighing roughly eight pounds per gallon, pooling water can lead to leaks and roof instability if you aren’t careful. This means that any roof that is built “flat” is still sloped to some extent to be able to drain. Flat roofs are typically defined as having a slope of 3-and-12 or less, and an average sloped roof is defined as 4-and-12 or greater.

Here at Crest Exteriors, we are roofing specialists. It doesn’t matter if you’re in need of low-slope roofing or you have a high-pitched roof in need of a new installation, we are able to meet all your roofing needs. In addition, we are experts at repairing or replacing weather-damaged roofing to make sure your roof never stops protecting your home. Please contact any of our locations in Colorado or Texas for more information about our services!