A roof’s pitch, or slope, represents its steepness. Roof pitch is expressed as a ratio indicating the number of inches the roof rises vertically for every 12 inches it extends horizontally. For example, a pitch of 4/12 means the roof rises four inches for every 12 horizontal inches. The higher the number, the steeper the pitch.
We’ll explore the most common roof pitches found on residential buildings, how roof pitch affects roofing material choice, and common roof problems associated with improper pitch.
Common Residential Roof Pitches
While roof pitches vary from building to building, there are four roof pitches that are the most common among residential homes. Below, we detail and compare these common roof pitches.
4/12 Roof Pitch
A 4/12 roof pitch rises four inches vertically for every 12 inches horizontally, creating a gentle slope. Roofs with a 4/12 pitch are easier to walk on, and you’ll spend less on materials to cover the roof and labor due to ease of installation.
6/12 Roof Pitch
A 6/12 roof pitch has a 6-inch rise per 12 inches of run, creating a medium slope angle. A 6/12 roof pitch is steeper and has moderate snow-shedding abilities while maintaining traditional appearances. A steeper roof can protect your home from structural damage due to the buildup of heavy snow and ice dams.
8/12 Roof Pitch
An 8/12 roof pitch rises 8 inches per 12 inches of run, resulting in a steep slope that’s triangular in shape. A steeper roof has several benefits, such as enhanced rain runoff and snow shedding. A common problem for flat or low-pitch roofs is pooling water and snow buildup, so a steeper roof, such as one with an 8/12 pitch, is better for areas receiving heavy precipitation.
12/12 Roof Pitch
A 12/12 roof pitch is very steep, rising 12 inches per 12 inches of run. This type of roof is prone to roof leaks. Falling debris tends to collect in the gutters on steep roofs, and failing to regularly clean and remove the debris can cause water to back up, pool, and leak through the roof.
Roof Pitch Comparison
Roofs with a pitch of 4/12, 6/12, 8/12, or 12/12 have varying angles and are visibly different, but they do share some key traits. Most shingle options work with the most common roof pitches, but some roofs may require higher-quality shingles and additional supports or reinforcements.
Below is a chart comparing the most common roof pitches.
| 4/12 Pitch | 6/12 Pitch | 8/12 Pitch | 12/12 Pitch | |
|---|---|---|---|---|
|
Rise/Run |
Rises 4” for every 12” of run |
Rises 6” for every 12” of run |
Rises 8” for every 12” of run |
Rises 12” for every 12” of run |
|
Slope Angle |
18.4 degrees |
26.6 degrees |
33.7 degrees |
45 degrees |
|
Shingle Options |
Asphalt, clay or concrete, metal, slate, and wood |
Asphalt, clay or concrete, metal, slate, and wood |
Asphalt, clay or concrete, metal, slate, and wood |
Asphalt, clay or concrete, metal, slate, and wood |
Low Pitch Benefits
The biggest advantage to having a low-pitch roof is the cost. A low-pitch roof requires fewer materials and less labor during installation. A lower slope also provides easier walkability and accessibility. Here are the benefits of a gently sloping roof:
- Easier walkability and accessibility: A flat or low-pitched roof is easier to access and walk across without more than basic safety precautions.
- More affordable material cost: The lower the pitch, the less you’ll spend on materials. Higher-pitched roofs have a larger surface area and require more materials to fully cover the roof.
- Simpler installation: A lower-pitched roof has better accessibility and requires fewer materials, simplifying installation.
Steep Pitch Benefits
There are advantages to steep roofs, including more space and better protection against the accumulation of rainwater and snow. Not all materials work on a steep roof, but some material types, such as slate roofing, fare better on roofs with a steep pitch.
- Enhanced rainwater runoff: Rainwater will run down and off the roof more quickly and efficiently compared to a low-sloped roof.
- Improved snow-shedding ability: Snow slides off high-pitched roofs more easily. This reduces the potential for ice dam buildup or damage from heavy snow.
- Greater attic space: A higher roof gives homeowners the opportunity to build an attic for storage space or additional living space.
How Roof Pitch Affects Material Choices
Roof pitch can affect the materials you choose during installation. Most materials work on common roof pitches, but steeper roofs may require premium shingles, additional gutter supports, or reinforced framing.
Low-pitch roofs work best with commercial-grade roofing products, such as built-up roofing, tar and gravel, rubber, and standing seam metal. Average-pitch roofs work best with asphalt, wood, slate, clay, or cement. High-pitch roofs are heavier and may require lighter materials and extra support. Follow manufacturer guidelines for appropriate roofing materials based on pitch. Installation may require measuring for shingles to find the best types of shingles for your roof’s pitch.
Climate Considerations for Roof Pitch
Your roof’s pitch should also correspond to your local climate and weather conditions.
Steep roofs are the best roof types for colder regions where snow is common. A steep pitch can prevent snow and ice buildup. If the roof is too flat, heavy snow and ice can damage the roof structure or cause leaks. To minimize these risks, homeowners need to remove snow and ice and install an appropriate gutter system to manage heavy rainfalls. Check local building codes for minimum roof pitch requirements in your region.
Common Roof Pitch Problems
A roof with an improper pitch risks leaking, ponding, and other problems. This is why proper roof installation is essential to maintaining your home’s structural integrity. Below some common roof issues associated with pitch:
- Pitch too low for shingle type: Some common roofing materials don’t work on low-pitch roofs. For example, the minimum pitch required for asphalt shingles is 2/12, because these shingles aren’t designed to withstand standing water. A lower pitch will not enable water to drain off quickly enough, and the shingles will get damaged.
- Insufficient slope for drainage: If your roof’s slope is not steep enough, water won’t be able to drain off. It can then pool and seep into your roof.
- Pitch too low to bear snow load: If you live in a colder region with frequent precipitation in the winter, your local building codes should specify the minimum slope required to prevent damage from snow and ice buildup.
Our Recommendation
The ideal roof pitch range depends on your location’s climate, your budget, and the shingles you want to use on your roof. Common roof pitches are between 4/12 and 12/12, with lower pitches requiring specific materials and appropriate drainage systems to prevent sitting water. We recommend getting professional input on the best slope for your roof.
Common Roof Pitches FAQ
What is roof pitch?
Roof pitch is the number of inches that a roof rises vertically per every 12 inches it extends horizontally. The most common roof pitches are between 4/12 and 12/12.
How do you calculate roof pitch?
To calculate roof pitch, first, measure the vertical rise of the roof, which is the distance from the roof’s bottom edge to its peak. Then, measure the horizontal run of the roof, which is the distance between the two points on the roof’s bottom edges. Next, divide the rise by the run, and multiply the result by 12. The pitch is then expressed as the number calculated over 12; for example, 4/12.
What is the standard roof pitch?
Standard roof pitches are 4/12, 6/12, 8/12, and 12/12. Anything over 8/12 is considered a steep roof.
Can you change roof pitch?
Yes, you can change the roof’s pitch, but it requires altering the roof’s internal structure. Consult with a professional to determine if it’s possible for your home.
What causes a low-pitched roof to leak?
The most common cause of leaking on a low-pitched roof is poor drainage. The lack of slope makes it more difficult for water to run off the roof.
