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How To Measure a Roof For Shingles

How To Measure A Roof For Shingles

Whether you’re buying shingles for a brand-new house or re-roofing your home, you need to understand that a successful roofing project usually requires a significant investment of both money and time. As you begin looking for materials, you may wonder how to measure your roof for shingles. Roofing materials are priced per square foot and can vary greatly in cost. It’s best to contact a professional roofer to measure the size of your roof. However, if you want to get a rough estimate, you can climb the roof and measure it yourself.

How to Calculate the Total Roof Square Footage

To calculate your estimate, follow these steps. First, you have to measure the width and length of each roof plane, including dormers. Next, to get the square footage of every rectangular plane, multiply the length and the width.

Make sure to document the number of skylights, chimneys, or other obstructions and also include dormers. Also, measure the length of your house throughout the first step to calculate your total area. Finally, add the square footage of each plane together to calculate the total roof square footage.

Roof surfaces are measured in “squares,” and each square is 100 square feet. So if your roof is 20,000 square feet, that means you’ll need 200 squares to coat it.

As you’re shopping for materials, remember that you’ll probably need shingles for ridges and hips of the roof and also starter shingles to place along with the rakes and eaves. Your roofer will tell you how many extra shingles you may need for the project.

Determine the Roof Pitch

Next step, you need to measure the pitch (also known as the slope) of the roof deck. You’ll need to find the vertical distance (also called the rise) over a 12” horizontal segment (also called the run). Write down these numbers as roof rise overrun – the vertical measurement should be listed first and the horizontal one second. Keep in mind that the roof pitch is dramatically different for houses with a flat roof than houses with a steep roof.


A new roof also includes the purchase of underlayment, a waterproof or water-resistant barrier material adhered directly to the deck, under your chosen material. If you get 20,000 square feet of shingles, you will also need to get a matching 20,000 square feet of the underlayment.

You don’t have to worry if you don’t know how to measure your roof for shingles. The roofer can measure the roof surface to calculate the square footage, which will determine how many shingles you must get to fully cover the roof’s planes.

Also, climbing on a roof is not safe, so we don’t recommend measuring the roof planes yourself.  The measurement must be correct if it will be used to buy roofing materials. So it’s better to contact a reliable roofer to get an estimate than to do it all yourself.

Are you thinking about a home improvement project? Feel free to contact 1-800-HANSONS for a free estimate.

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