An Introduction to Roof Pitches
There are more roofing materials to choose from than ever before. It may seem like any material is fair game for your home, but unfortunately, that’s not the case. Many factors determine which materials are structural supportable by your roof, like a roof's pitch.
What is roof pitch?
"Pitch" is the term for the slant, slope, or angle of your roof.
Roof pitch is designated by a ratio—two numbers divided by a slash or a colon, like 5:12 or 5/12. (Read: 5 over 12)
The numerator (first number) refers to the height of the roof. The denominator (second number) refers to the length of the roof.
For example, a roof pitch of 5/12 is a common ratio in many homes. For every 12 inches horizontally, the roof increases 5 inches vertically.
No matter how it’s expressed, it defines the same thing. Most homeowners have roof pitches in the range of 4/12 to 8/12. However, (nearly) flat roofs may express ¼ /12, and perfect 45-degree angle roofs are 12/12.
How do I calculate my roof's pitch?
Calculating the roof’s pitch from the underside of the roof is an accurate method to determine the correct ratio because there’s no roofing material to create an uneven surface.
Grab a level, a tape measure, and a pencil, and head up to the attic.
What are some other common roof pitches?
Homes built in the 1960s have a very gradual slope, just enough to drain water. These close-to-flat roofs were fashionable in their time period and might be as low as 1/12.
Victorian-era houses often had the exact opposite approach compared to architectural choices of the 1960s. These roofs were often sharply angled and steeply pitched. In these rare cases, the numerator is greater than the denominator, sometimes even as high as 18/12.
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What pitches are best for various roofing materials?
Built-Up, Torch-Down, and Standing Seam Metal
Contemporary urban homes, industrial buildings, and commercial businesses have roof pitches in lower ranges, such as 1/12 to 3/12. Roofs with such gradual slopes are constricted to built-up, torch-down, or standing seam metal roofing materials.
Conventional composite shingles don’t allow water to drain fast enough from low-pitched roofs and are not advisable for these properties.
Asphalt and Composite
Asphalt and composite shingles are ideal for roofs in the 4/12 to the 12/12 pitch ratio. They are the two most common roofing materials, and they are the most serviceable type of shingle material when it comes to roof pitch.
Wood Shake and Slate
Shake and slate shingles are great for roof pitches in the 5/12 to 12/12 ratio. They perform well in the same pitch gap as asphalt and compositions shingles but are more prone to leaks because they don’t lock together as tightly.
How do I hire the best contractor for my roof?
Consult an experienced roofing contractor if you wish to install a more unconventional material on a low or high pitched roof.
Hometown Roofing Contractors can help you identify the best roofing contractor for your next installation. You can consult multiple contractors, determine the best quotes, and see what other customers have to say.
Learn more about hiring a roofing contractor: