How much pitch does a roof need for shingles

It's easy to imagine that the choice is purely an aesthetic or economic one—that you pick a roofing material according to what you like or what you can afford. That's only partly true.

Other factors determine which roofing materials you can use. One solid factor is the pitch of the roof, also known as the roof slope. Roof pitch can instantly change the conversation. You may have your heart set on classic composite shingles on your roof. But if the roof pitch is below a certain ratio, you may be forced to install a different type of roofing—perhaps rolled roofing or standing seam metal roofing.

Pitch describes the angle, slope, or slant of your roof. Roof pitch designations are comprised of two numbers indicating a ratio.

Or, a colon can replace the slash, as in or Either way, the notation designates a ratio between two measurements of the roof—a numerator and denominator. A roof with a vertical measurement anywhere along its slope of 2 feet and a horizontal measurement of 4 feet has a pitch. To adjust for roofing purposes, you would multiply the second number by three. The first number must be multiplied by three, too. The roof pitch, then, is The pitch of a roof is nothing more than a ratio that indicates how much rise there is in the roof over a unit horizontal distance.

When you see the ratio , this means that for every 12 horizontal feet, the roof changes 5 feet in vertical height. When you see a ratio of , this means that for every 12 horizontal feet, the roof changes 8 feet in vertical height.

The short, simple answer is has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. Asphalt shingles continue to be the most widely installed roof covering option in North America.

They provide excellent weather resistance, great value and, now more than ever, a tremendous range of beautiful designs and color blends. And of course, their ease of installation and adaptability to just about any roof shape is another reason for their success. In recent decades, home designs have tended toward steeper roofs, but there are many instances where a house may have a lower roof slope, or a portion of the roof that is at a lower slope.

Conventional Slope 4 in 12 and up. Roof slopes are most commonly defined by the rise-over-run ratio. You can measure the roof slope on the bottom side of the roof deck at an easily accessible point such as the rake, using a tape measure and simple geometry.

Alternatively, there are smart phone apps that can help , but shingle manufacturers distribute convenient pitch estimator cards which provide a quick way to ballpark the slope. A handy roof slope estimator can help you determine if your roof slope is likely too low for shingles.

The majority of North American residential roofs have historically been constructed with a slope between about and Asphalt shingles are an effective roof covering material for sloped roofs that can be successfully used on slopes as low as With respect to shingle application, roof slopes from to less than Additional underlayment protection with special application methods are required when asphalt shingles are installed on a low slope roof, following the manufacturer's application instructions.

Because of their lower slope, these roofs are more susceptible to water entry, primarily for two reasons: severe ice dams and wind- driven rain. Therefore, underlayment requirements are increased to enhance the water shedding property of the roof system as a whole. The acceptable underlayment installation options for low slopes are described in the Canadian Standards Association asphalt shingle application standard CSA A