It is essential for roofers, contractors, and homeowners to know accurately how to measure roof slope. Knowing your roof pitch is important for safety, accuracy, and material selection, whether you are replacing a roof, installing solar panels, or checking for proper drainage. In this article, we will look at five methods to easily measure roof slope, outdated methods to check slope yourself, and new options to measure slope digitally.
What Is Roof Slope and Why It Matters
The roof slope (also referred to as roof pitch) is the angle or steepness of a roof, commonly expressed as the ratio of vertical rise to horizontal run. For example, a 4/12 roof slope indicates that, for each 12 inches horizontally, the roof will rise 4 inches vertically.
Your roof slope will impact:
- Material choice (asphalt shingles vs. metal or tiles)
- Water drainage performance
- Safety during roof installation and inspection
- Appearance and structural stability
When you understand how to measure roof slope, your roofing project will be safe and effective with respect to budgets.
1. Measure Roof Slope Using a Level and Tape Measure
One of the most precise and conventional methods for how to measure roof slope consists of a level and tape measure. This is a simple measurement that doesn’t require complicated tools.
Step-by-Step Instructions :
- Put a 12-inch level horizontally across your roof surface.
- Mark the 12-inch point on the level.
- From that mark, take a vertical measurement from the roof surface up to the bottom edge of the level.
- The measurement you take in inches is the overall rise of your roof.
For example, if the rise is measured at 6 inches, your roof slope is 6/12 or 6 in 12.
Formula:
Roof Slope = Rise / 12
This procedure is very popular because it is quick to perform, inexpensive, and is an accurate measurement when properly executed.
2. Use a Roofing Square (Carpenter’s Square) for Precision
A roofing square or speed square is a professional tool that allows for the fast and accurate measurement of roof pitch.
Using a Roofing Square
- To use the square, place it at the edge of a rafter or directly on the roof deck.
- Using the square, align the pivot point with the bottom edge of the rafter.
- Tilt the square until one of the two sides of the square is flush with the roof.
- Using the square, read the degree of slope directly on the markings.
Using a pitch conversion chart or a roof pitch calculator can also be used to convert degrees to roof pitch.
Example:
18.4° = 4/12 , 26.6° = 6/12
Building professionals prefer this method as it is fast and accurate.
3. Measure Roof Slope from the Attic
If you cannot or do not feel safe getting up on the roof, it is incredibly easy how to measure roof slope from inside your attic, using the same level and a tape measure.
Follow these steps:
- Put a 12-inch level against the underside of a rafter.
- Hold it horizontal and mark where it meets the rafter.
- From that point, measure vertically to the rafter’s surface.
- The number you get in inches is your rise (vertical measurement) per 12 inches of run (horizontal measurement).
This method works, and is safe, as long as you are careful to get it level during the rain or snow when getting on the roof is dangerous.
4. Calculate Roof Slope Using a Smartphone App
Technology has simplified the process for accuracy in measuring roof pitch. Roof pitch calculator apps measure roof slope angles with your phone sensors and camera, and do it easily and have become very popular.
These are some roof angle slope apps:
- Pitch Gauge App
- iRoofing
- Angle Finder App
Church roof pitch calculator.
How it Works:
- Open the app and point your phone’s camera at the roof level.
- Use the guideline they provide to align the screen with the roofline.
- The app will auto-populate the pitch or degree of your roof.
These are great apps for a quick, easy, and good estimate, especially while completing roof inspections or getting some estimating for a project.
5. Measure Roof Slope Using Aerial Roof Reports
Aerial roof measurement services, such as Aerial Estimation, provide professionals who want the best accuracy without getting on a roof with slope calculations based on satellite images.
Benefits of Aerial Roof Reports:
- No physical access to the roof is required (recommended for safety)
- 3D modelling is very accurate
- Extensive roof data is provided (area, pitch, dimensions)
- Saves contractors time and insurance claims
Provide your property address, and you will have a detailed roof report provided to you with slope calculations in multiple pitch formats. The easiest and most professional way to measure a roof pitch is here.
Understanding How to Measure Roof Slope Ratios and Conversions
| Roof Pitch | Degrees | Roof Type |
|---|---|---|
| 1/12 | 4.76° | Very Low Slope Roof |
| 4/12 | 18.43° | Low Slope Roof |
| 6/12 | 26.57° | Medium Slope Roof |
| 9/12 | 36.87° | Steep Roof |
| 12/12 | 45° | Very Steep Roof |
Most residential roofs range from 4/12 to 9/12, providing the ideal balance between aesthetics, performance, and maintenance.
Tips for Accurate How to Measure Roof Slope Measurement
- Be certain to check the level is exactly horizontal before taking the measurement.
- For safety reasons, it is best not to access roofs in wet or windy conditions.
- Make sure that you check your readings for consistency.
- For larger or complicated roof structures, it is best to rely on digital technology or aerial data.
- Always document measurements in both pitch ratio and degrees for documentation purposes.
Common Mistakes to Avoid
- Measuring from an uneven surface or damaged area.
- Using a short level (less than 12 inches) for slope readings.
- Forgetting to account for roofing material thickness in final calculations.
- Ignoring conversion errors between pitch ratio and degrees.
By avoiding these errors, you ensure precise results and a smoother roofing process.
Final Thoughts
Determining how to measure roof slope of your roof is a straightforward process. With a few tools—a traditional level and tape measure, a smartphone app, or measuring technology—you can accurately assess the pitch of your roof in just a matter of minutes.
Homeowners can benefit from knowing roof slope for renovations or repairs, roofing material selection, and roofing companies get faster estimates, more accurate numbers, and more trust from their clients.
Learning how to measure roof slope correctly and easily is not just a technical skill, but an important process for maintaining and constructing safe, durable, and efficient roofing systems.
FAQs About Measuring Roof Slope
- How can a roof slope be measured the easiest way?
If you want the easiest and safest way to measure the slope of a roof, consider using aerial roof measurement services. You can get accurate roof slope and area information without ever climbing on the roof. Roof slope and area data can be obtained from satellite imagery. For instance, aerial measurement reports can be purchased without ever having to set foot on a roof.
- Is it possible to measure my roof slope without climbing up on it?
Definitely! You can measure your roof slope remotely via Aerial Estimation’s advanced technology. With high-resolution aerial imagery and a 3D modelling system, we can calculate slope, pitch, and dimensions accurately.
- Why is it important to understand the roof slope?
Understanding the roof slope helps you choose the right roofing materials, plan and budget for the proper drainage, and help to accurately calculate repair or replacement costs. This slope will also help with the overall safety and efficiency of the roofing process if you have a contractor provide two slope measurements.
- How accurate are reports that measure roofs using aerial data?
Aerial roof measurement reports are incredibly accurate, often within 1-2% of an on-site measurement. They provide detailed calculations of slope, pitch, and square footage information that contractors, insurers, and homeowners can use.
- Is Aerial Estimation able to generate reports for both Canada and USA?
Absolutely! it provides precise roof measurement reports for roofing professionals and homeowners throughout both the USA and Canada.
🌎 Get your report faster at www.aerialestimation.com