What Are Common Roof Pitch Angles and What Does That Mean for My Roof?

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Take a drive around your community and you’ll notice plenty of different rooftops with many colors and made from a wide variety of materials. You’ll also notice there are as many different roof pitch angles as there are rooftops. In other words, some roofs are a lot steeper than others. What’s the purpose of these different roofing angles? How significantly do they matter with regard to the building itself? How do builders choose which roof pitch angles to use?

Read on to learn a little more about the common roof pitch angles and what it means for your roof in particular.

What, Exactly, Is Roof Pitch?

Roof pitch is actually measured as a numerical ratio; it’s simply a number expressing the measurement of the roof’s slope. The specific ratio tells you how many inches the roof rises for every 12 inches of depth (also known as “run”), meaning that if the roof rises 7 inches for every 12 inches of depth, the ratio—or pitch—of the roof will be 7:12. This may also be expressed as an angle: for a ratio of 7:12, the angle would be 30.5 degrees.

Of course, when you’re identifying the pitch on a roof, you don’t necessarily need the exact ratio. While that ratio will be important for your roofer during the construction phase, you can usually identify most of the common roof pitch angles visually.

The Purpose of Angled Rooftops

Roofs have angled pitches for exactly the reason you would expect them to: to allow rain and snow to slide off safely. This is important because water can be extremely destructive. If rain and snow pile up on your rooftop, the water will eventually seep through the roofing materials and cause catastrophic property damage.

Because weather is the key factor in the angling of the roof, you’ll find that rooftops in a region are different depending upon the area’s climate. Areas that are extremely wet and rainy will see much steeper rooftops, as will regions that receive a lot of snow and hail every year.

Higher angles have other purposes too, with regard to storage space. A roof with a very low angle indicates the house won’t have much of an attic. A steeper angle, on the other hand, means the home should have plenty of storage area above the regular living space.

The Most Common Roof Pitches

Different roof pitch angles are chosen by builders depending upon the type of building, the amount of space required, the weather in the region, and aesthetic factors. The pitch angle depends largely upon the type of roof being utilized. Some roofs are more complex and may even feature several different angles.

Roofs usually have an angle anywhere from 4:12 to 9:12, although they’re by no means required to remain within these ratios. If the ratio is less than 4:12, the roof will be referred to as a low-slope roof. The opposite also exists: steep-slope roofs have a pitch greater than 9:12.

You may be wondering if the flat roofs frequently utilized by commercial and apartment buildings have a ratio of 0:0. In the vast majority of cases, they do not. While they are still referred to as “flat” roofs, they almost certainly will have some kind of angle—2:12 or less—to allow rain and snow to slide off the top of the building.

The Different Roofs You’ll See

There are many different types of rooftops, of course, and the roof pitch angles will vary depending upon their design requirements.

Among the most common types of rooftops in the United States are gable roofs, sometimes also referred to as pitched roofs. These are the pointed rooftops that come to mind when you picture a cottage in the woods. They can have an incredible amount of variance due to their simple design. They are vulnerable, however, to heavy winds and other extreme weather conditions.

Hip roofs allow for a little more stability. They feature four slopes that come together to form ridges at the top of the building. They usually work best with lower angles of about 4:12 to 6:12. Gambrel roofsbetter known as barn roofs—have two sides and very steep slopes, while skillion roofs have only one side (these are the types of roofs you’ll see on top of sheds). Multiple single-sided, sloped roofs are referred to as sawtooth roofs.

There are many, many other types of roofs, but these are the most common for houses in the United States.

What These Roof Pitches Mean

The angle of your roof has a practical meaning for you as a homeowner. The mentioned storage space issue and weather concerns are chief among these. There are other concerns as well. The angle of your rooftop greatly affects the type of building materials you can make use of. It also affects the ease of repairs: a roof with a low slope will be much easier for a roofer to walk around on than one with a steeper slope.

Roofs that have flatter slopes shouldn’t utilize shingles. Because they don’t have much of an angle, water and snow will build up on top of them and can easily seep between the shingles. For a flat roof, the best material to use is some sort of membrane; often, asphalt or gravel are utilized. On the other hand, roofing shingles made from wood, slate, or other materials can be excellent for rooftops with greater slopes, both for keeping the elements out and for an aesthetic sense.

Making Sure Your Roof Has the Right Pitch

Because there are so many variables involved in ensuring your roof has the optimal materials for its roof pitch angle and is being repaired properly, you’ll need to utilize the services of a professional roofer. Contact Interstate Roofing for advice on how to ensure your roof is working at its maximum efficiency in terms of protecting you from the climate and the elements. They’ll ensure you have the right materials as well as perform repairs in a safe manner to keep your roof in excellent condition for years to come.

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