The term’ roof pitch’ refers to the angle or slope of a roof. It is typically presented in one of two ways: as a ratio or a percentage. Understanding what these terms mean and calculating them can help you better understand the roof’s pitch and how to measure it.
Understanding and measuring the roof pitch isn’t just a technicality; it’s a practical step that can significantly impact your project. Knowing the roof’s pitch before installation can ensure you have the correct number of materials, making your project smoother and more efficient.
How To Calculate Roof Pitch
As mentioned, roof pitch is calculated in degrees and ratios, so knowing how to calculate both options can help ensure everything is correct and you know what to expect.
This is where geometry is essential. Geometry is vital for calculating the roof space and giving a more accurate projection of the roof’s size, bringing it into a 3D form from 2D dimensions.
When we talk about the ‘pitch value’ assigned to hips, rakes, and step walls, ‘we’re referring to these roof features’ specific angles or slopes. These features often have different pitches than the main roof, and not accounting for them in your calculations can lead to inaccurate measurements and material estimates. By incorporating the correct roof pitch, including these additional pitch values, you can improve the accuracy of your project and work towards a better compilation and preparation.
To calculate your roof pitch, you will need a few tools. These include a scientific calculator, a level, a tape measure, and somewhere to jot down your measurements and pitch once you’ve calculated them for future reference. Having these tools ready before you start measuring will make the process smoother and more efficient.
Calculate Roof Pitch in Ratio
When calculating roof pitch as a ratio, the pitch is always determined as x:12. The ’12’ refers to the horizontal run, and the first number is the inches over 12 from the horizontal run. Historically, most pitches are between 3:12 and 12:12, 3 inches over 12 inches above the horizontal run. For instance, a 3:12 pitch is considered a low slope and is often used in residential construction, while a 12:12 pitch is a steep slope and is often used in commercial or industrial buildings.
To calculate the pitch of the roof as a ratio flow, these steps;
- Grab a level and a tape measure.
- Hold the level steady against the roof rafters. Measure 12 inches towards the pitch from the rafter. Once you have this measure from the roof’s peak to the 12-inch marker, this is your pitch number, i.e., your first number for the equation.
- Display your pitch as an equation. For example, if the pitch is 6 inches over the 12-inch run, you should display it as 6:12 (or 6/12, if you prefer).
Calculate Roof Pitch As A Percentage
If you need to know the roof rises as a percentage instead of a ratio, you need to follow the same direction as measuring for a ratio. The difference is simply the conversion you use.
- Calculate as above using the 12-inch rise.
- Divide the rise by the run, e.g., 4:12, which will be 0.3333333333
- Use a scientific calculator to find the arctangent of the rise. This gives you your pitch in percentage form. For 4:12, it would be Artcan 18.43.
If you want to work this out without a calculator, follow these simple steps to get the pitch.
- Divide the rise by the run
- Multiply by 100%
Calculating the pitch of your roof is more straightforward than it may seem. For instance, if your pitch has a rise of 4 feet and a run of 8 feet, all you need to do is divide 4 by 8 and then multiply by 100%. This gives you 50%, meaning the roof’s pitch is under 45 degrees. It’s that straightforward! This simplicity should provide you with confidence in accurately measuring roof pitch.
How To Measure Roof Pitch Accurately
Understanding the rise and run concept is crucial when measuring your roof pitch, as it forms the basis of the most common method used. The rise is the straight-line distance from one roof’s edge to its highest point, while the run is the straight-line distance from one side of your house to another.
Let’s delve into a practical example to bring the concept of roof pitch measurement to life. Imagine you have an L-shaped house with an exterior wall that runs along one edge and then turns 90 degrees before connecting with another exterior wall. In this case, there will be two rises: one at each end where those two walls meet. Both rises would be equal—you’ve just gone up straight instead of turning at any point during those two spans.
It is essential to consider the challenges in measuring roof pitch for non-standard roof structures. For instance, how do we account for roofs that aren’t perfectly flat? A great example would be pitched roofs like gabled barns or shed roofs, which often feature large overhangs! If these overhangs were removed from our measurements, what kind of pitch would you be left with? These are essential considerations you need to consider.
Using Apps and Calculators to Measure Roof Pitch
It’s essential that you use a calculator or a roof pitch app or tool to ensure that you get the correct configuration and measurements for your project. Even being out slightly can impact the build and lead to mistakes.
You must have as accurate a calculation as possible, so you should always double-check your measurements and use trusted apps or calculators to help you convert your requirements to get the correct percentage or ratio for your roof pitch. If you don’t notice a mistake, the result will be delays and potentially an inefficient roof leading to leaks.
Knowing how to measure roof pitch is vital for many reasons. Not only can it help you to determine the materials you need, but it will also give you an overall better and more exact finish for improved quality and standards. From being able to order the right shingles for your roof to getting the proper slope for rain runoff or even carrying out repairs or renovations, knowing how to calculate the roof’s pitch is something you should be able to do before commencing any work in this area.