The way roofs are measured and roofing materials are calculated is not always simple. When trying to estimate the amount of shingles or other roofing supplies, you may have found that your calculations don’t match up with the way roofing companies or suppliers talk about their products. Instead, they may refer to roofing supplies in terms of roofing squares. What is a roofing square and how can we use it to calculate the roofing materials you’ll need? Let’s find out.

What is a Roofing Square?

The term roofing square does not refer to square feet or yards. In fact, it is a unit used to express 100 square feet, in order to simplify the grouping and ordering of roofing materials such as shingles, tiles, or other supplies. Roofing squares are commonly used to calculate the materials needed for roofing projects, so you may hear your roofing contractor or your materials supplier refer to your roof in these terms.

For help calculating the total roofing squares in your home’s roof, some manufacturers offer free roofing square calculators online, or you can have your roof assessed and receive a free quote from a professional roofing company. Or, you can DIY by measuring your roof yourself.

Measuring Roofing Squares

If you need to measure the amount of roofing squares your roof contains, you can do this simply by measuring the total square footage of your roof, and then using that amount to calculate the number of roofing squares it contains. Let’s go over 4 steps to do this safely and effectively.

#1 Prepare

First, make sure you have all the right equipment to get onto your roof and measure it safely. This will include a tape measure, a small notebook and pencil, a sturdy ladder, and a buddy to hold the ladder still and supervise while you’re on your roof. Tread carefully on your roof so you don’t slip or cause damage to your roof.

#2 Measure

To find the square footage of your roof, measure the length and width of each plane of your roof, including the sides of all dormers, into valleys, and all other roof design details that are covered with roofing materials. Find the area of each plane by multiplying the length and width.

#3 Calculate 

Add all the area totals together to get the total square footage of your roof.

#4 Convert

To find the number of roofing squares your roof contains, convert the square footage to roofing squares by dividing number you found in Step #3 by 100. For example, if the total square footage of your roof was 1700 square feet, your roof contains 17 roofing squares.

Keep in mind that roofing squares is not the only information you need when estimating the required materials for completing a roof replacement or installation. Roofing pitch also factors into the total amount and cost of materials for your roofing job. The higher the pitch of your roof, the extra materials you’ll need to cover your roof effectively. Also, if your roof has many complicated details like dormers and valleys, it will need more specialized materials to make sure these sensitive areas are reinforced against leaks or damage.

Measuring Roof Pitch

Roofing pitch is described in degrees, relative to a right angle. To calculate your roof pitch, you need to know the rise and the run of your roof.

  • The rise refers to the height of your roof, from the top of the wall to the peak of your roof where the planes meet.
  • The run is the distance between the roof plate and the point directly underneath the center ridge or roof peak

Once you’ve measured these two elements, you’re ready to calculate your roof pitch.

Finding Roof Slope

We find the roof slope by plugging the rise and the run into the pythagorean theorem, where the slope of your roof, or the rafter length (squared) = the rise (squared) + the run (squared).

For example if the rise of your roof is 6 feet, and the run of your roof is 12 feet, then:

(6×6) + (12×12) = the square root of 180, or about 13.42 

This completes our triangle, so we know the length of all sides.

Calculating Roof Pitch

You can find the pitch of your roof by dividing the rise by the run. Using our example that would be 0.5 or 50 percent. If you want to express this percent as an angle, you’ll need to plug the percentage into this equation using a scientific calculator or an online tool:

Pitch angle = arctan(or tan-1) x (pitch percentage)

Using our example: arctan (0.5) = 26.57 degrees

Now that you know how to measure your roof, calculate a roofing square, and find your roof’s slope and pitch, you should have all the information you need to order materials for your roof! It’s always a good idea to check your calculations with a professional roofer and make sure all materials are installed correctly to give your roof the best, longest-lasting protection.

Looking for a bit more roofing information? Whether you’d just like a bit more help figuring out how many roofing squares are in your roof, or you’re interested in a brand new roof, the experts at Werner Roofing would love to help. Give us a call or reach out to our team online with any and all roofing questions.

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