Home > Roofing > What Is Roof Pitch? | How To Calculate Your Roof Pitch

What Is Roof Pitch? | How To Calculate Your Roof Pitch

Updated Nov 22, 2022

Updated Nov 22, 2022

Home > Roofing > What Is Roof Pitch? | How To Calculate Your Roof Pitch

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A roof’s pitch is a measurement of its angle or slope, and it’s an integral aspect of your home. Roof pitch plays an essential role in your roof’s design, affecting what type of materials you can use and how well snow, ice, and water drain from your roof.

Roof pitch is a common term in the roofing industry, but one many people are unfamiliar with. This article will examine why roof pitch is important and how you can calculate your roof’s pitch.

What Is Roof Pitch?

Roof pitch is essentially the roof’s angle, slant, or slope. Generally, roofers express pitch as the amount of rise (in inches) for a single horizontal foot of length. The higher the first number, the steeper the pitch typically is.

For example, a 6/12 roof would vertically rise 6 inches for each horizontal foot. That will have a sharper angle than a 3/12 roof, which rises 3 inches vertically for every foot of length.

Roofs fall into one of four categories, depending on their pitch. The roof category will largely determine the materials you’ll need to use.

Flat Roof Pitch

Flat gravel roof on a red apartment building
Canva

A flat roof has a pitch of less than 2/12 but with a minimum of ¼ inch of rise per foot of length. While these roofs have a minor slope, many roofers refer to them as flat roof pitches. They’re common on commercial buildings, though you find them as part of some homes.

Low-Pitched Roofs

Home with a low-pitched roof made of clay tiles
Canva

A roof pitch between 2/12 and 4/12 is considered a low-pitched roof. These are somewhat angled but not much steeper than a flat roof.

Many commercial buildings feature low-pitched roofs, which are much cheaper than their steeper-sloped counterparts. You may see these roofs on structures such as factories and warehouses.

Conventional Roof Pitch

Asphalt shingle roof on a vinyl home
Canva

Most homes built today feature conventional-slope roofs. These roofs feature a slope between 4/12 and 9/12. A traditional gable roof typically has a conventional pitch.

High-Pitched Roofs

Steep metal roof with red underlay
Canva

High-pitched roofs, also known as steep-slope roofs, feature a pitch of more than 9/12. These roofs feature a sharp rise, climbing 9 inches or more for each horizontal foot of length. They create a striking finish on many homes with modern architecture.

Roof Pitch and Angle Chart

Roof PitchAngle (Approximate)
1/124.5°
2/129.5°
3/1214°
4/1218.5°
5/1222.5°
6/1226.5°
7/1230.5°
8/1233.75°
9/1237°
10/1240°
11/1242.5°
12/1245°

How To Calculate Roof Pitch

Infographic showing how to calculate roof pitch from the inside of your attic
Image Source: Elisabeth Beauchamp

Knowing your roof’s pitch is essential for nearly every roofing-related project, including replacing the roofing material, installing skylights, or incorporating an addition. Luckily, measuring your roof’s pitch is a quick and easy process. You don’t even need to climb onto your roof — you can complete this project from the attic.

Here’s what you’ll need:

  • Pencil
  • Tape measure
  • 18” or 24” level

Before you start:

  1. Measure 12 inches from the end of the level and mark the spot with your pencil. This will allow you to measure one horizontal foot of length easily.
  2. Once you’re in your attic, position the end of your level against the bottom of a roof rafter.
  3. Make sure the level is perfectly flat.

Once the level is in place, measure from the 12-inch mark on the level up to the underside of the rafter. Your measuring tape should create a 90-degree angle or right triangle with the level and rafter. Measure the number of inches between the bottom of the level and the roof rafter. This is your vertical rise.

If your measurement is 4 inches, your roof has a 4/12 slope.

Standard Roof Pitch

There is no standard roof pitch, though most roofs have a pitch that falls between 3/12 and 9/12.

As your architect develops the ideal roof pitch for your home, they’ll consider the appearance and other factors, including the weight of the roofing materials like shingles or tile, the cost, the projected lifespan of the roof, and the amount of maintenance it will need.

Roof Pitch FAQs

What is the smallest pitch a roof can have?

The minimum pitch a roof can have is ¼:12. So, for every horizontal foot of length, the roof rises ¼ of an inch. These roofs are nearly flat, so they don’t work for all climates and roofing materials.

How much does getting your roof pitched cost?

If you’re looking to know the roof’s pitch, a contractor will likely do this for free when they come to give you an estimate on a roofing project. Just ask your roofer about the pitch of your roof.

Changing an existing roof to a different pitch is a big job. Generally, you should budget between $15,000 to $20,000. However, several factors can affect the cost, such as the size and complexity of your roof layout and the type of materials you choose.

What is a 4/12 roof pitch?

A 4/12 roof pitch indicates a roof that rises 4 inches for every horizontal foot of length. This particular roof pitch translates to approximately 18.4 degrees.

What is the best roof pitch?

The best roof pitch for your home depends on several factors, especially the amount of wind or snow you typically receive. For example, if you live in an area that receives heavy snow throughout the winter, you’ll need a roof with a decent slope. This way, the roof can shed the snow as it melts, preventing it from pooling on the roof or building up and straining the roof structure.

Aside from climate, you’ll need to consider the type of roofing material you want to use for your new roof. Certain roofing materials don’t work with some slopes. For example, you may need special shingles for low-slope roofs. Flat roofs often need a specialized roofing membrane. Be sure you choose a material that works with the pitch of your roof.

Consult a roofing professional if you’re unsure about these factors and how they apply to your roofing project. Raising the pitch of your roof or building a new roof is a significant project, usually one best left to the professionals. However, a steep roof may be better, depending on your location.

What roof pitch is considered walkable?

Many roofers consider roofs with pitches of 7/12 or lower “walkable.” Any steeper than that and most roofing contractors will take additional precautions. Roofs with pitches higher than 8/12 usually require roof jacks or scaffolding for safety.

The steeper the slope, the harder it is to walk on. Even if you have a gentle-sloped roof, it’s usually best to avoid spending excessive periods on any type of roof.

What does a 12/12 roof pitch mean?

A 12/12 roof pitch is a steep-sloped roof that rises 12 inches for every horizontal foot of length. These roofs feature an angle of approximately 45 degrees, which is considered very steep.

What does a roof pitch have to do with water drainage?

The pitch of a roof plays a vital role in how well your roof sheds water. On a completely flat surface, water tends to pool in the middle. If you live in an area that receives heavy snow, snow might also be unable to fall from the roof. Instead, it would build up and strain your roof — potentially causing it to fail.

Local building codes typically reflect the climate in your area, requiring a roof slope within a specific range.

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