Figuring out the slope and pitch of a roof is an important task. Pitch adds to the overall aesthetic of your house, determines how likely your roof is to collect leaves and other debris and even impacts how much moisture your shingles hold. The steepness also can influence the life of your roofthe steepness.
The terms “slope” and “pitch” are often used interchangeably, but there are slight differences between the two:
- Slope: Slope is the ratio of the vertical rise compared to the horizontal span and is shown in inches per foot. So, a roof that rises six inches for every foot of run has a “6 in 12” slope.
- Pitch: Pitch is shown as a fraction, which divides the rise by the span. It isn’t necessarily a 12-inch run, but the entire span. So, if the roof has a 24-foot span and has a 4-foot rise, then it has a 1/6 pitch.
For the homeowner’s or do-it-yourselfer’s purposes, it’s likely okay to use the terms interchangeably unless you’re installing the roof yourself and specifically need the exact measurement of slope and pitch for some reason.
There are several things you must consider when determining the pitch of the roof — it’s about far more than just the pitch. You also must consider style, materials and many other factors.
Reasons for Measuring Pitch
Contractors determine the roof pitch by measuring the vertical rise for every 12 inches of the roof. Slopes range from low — about 2/12 slope — to severe slope, about 12/12 slope. The pitch determines what type of roofing materials you can use safely, how well rain runs off the roof and the estimated lifespan of your roofing system.
You should know the pitch of your roof when seeking a quote from a contractor. Of course, they can measure the pitch for you, but if you already know the pitch, it also shows that you’re savvy. This could prevent the few untrustworthy contractors out there from trying to fleece you out of a few extra dollars.
Using Tools for the Task
There are several different techniques to measure pitch. The simplest method involves buying a tool called a pitch finder. Place the device on top of a roof or under a rafter in the attic, and it calculates the pitch for you. The tool is fairly inexpensive, and you can find it at hardware stores as well as online.
If you wish to double-check the tool’s accuracy — or you don’t have a pitch finder on hand — you can also manually measure and calculate roof slope. Use a speed square and go inside the attic. Mark a plumb line on one of the common rafters with a level and a pencil. Place the speed square on the plumb line and read the pitch on the square. Measure in several spots to be sure your measurements are accurate.
Taking Advantage of Warranties
Most roofing systems come with some type of warranty. Whether you’re using metal roofing or asphalt shingles, each manufacturer has specific requirements, or you risk voiding the warranty. For example, some types of roofing are not compatible with some slopes. Manufacturer warranties clearly spell this out, so make sure you aren’t inadvertently voiding your warranty by using the wrong materials with the wrong slope.
Using the right materials for your roof slope also ensures the roofing lasts as long as possible. A flat roof won’t do well with inexpensive asphalt shingles, for example. Fortunately, most residential homes have a moderate roof pitch.
Knowing What Pitch Means
If you’re measuring to get quotes from contractors for a possible addition to your house, some basic information that might come in handy is knowing how to describe the pitch in general terms. The three diverse types of pitch include:
- Low-Pitched: A low-pitched roof is generally below three and a half. Low-pitched roofs don’t do well with asphalt shingles, and they also need more frequent maintenance than other pitches.
- Medium-Pitched: A medium-pitched roof runs between three and a half and seven and a half. This is the most common pitch in the United States. Most asphalt shingles work well on this type of roof, and this roof pitch doesn’t require specialized equipment to work on safely.
- Steep-Pitched: Steep-pitched roofs are anything measuring over seven and a half. Because the pitch is so steep, a roofer needs specialized equipment to replace shingles or work on your roof. Otherwise, the workers or the materials risk sliding right off the roof and onto the ground below. The good news is that a steep roof pitch tends to need less maintenance and tile replacement.
If you’re adding an addition to your home or attaching a garage, you’ll want to match pitch as closely as possible.
Why It’s So Important to Know Pitch
Even if you’re not the one installing a new roof or addition on your home, it’s important to understand the accurate slope and pitch descriptions of your roof. This ensures your contractor uses a product built for your slope of the roof, and thus the replacement lasts longer than if you use a product not meant for that slope.
Megan
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What a lovely guide on the different slopes a pitched roof has. Thank you for making us aware of the types of a pitched roof. I am planning to have ground floor extension built and I am debating whether to go with a flat roof or a pitched one. What do you think would be a better choice?
This is such a great post, especially for newbie investors. Great article, very informative and something to think about. Thank you very much for sharing this article. Hope you write more thought-provoking articles.