How to Measure a Roof for Shingles

DIY enthusiasts planning roof repairs must understand how to accurately measure their roofs for shingles. Knowing how to measure a roof for shingles is crucial to ensure you obtain the right amount of materials for the job. 

To determine the correct quantity of shingles, you can utilize either a roof square footage calculator or a roofing square calculator. Failing to measure the roof properly may result in incorrect measurements being inputted into the shingle calculation, leading to the purchase of an excessive amount or an insufficient number of shingles.

To obtain precise roof measurements, start by ascending to the roof’s summit equipped with a tape measure, notepad, and pencil. Carefully measure each section individually before calculating the required square footage, roofing squares, and the number of shingle bundles needed. It’s important to follow these steps diligently while ensuring you take the necessary safety precautions to measure your roof accurately.


Before You Begin to Measure a Roof for Shingles

Before climbing onto the roof, make sure to draw an overhead view in your notepad. This will enable you to accurately record the measurements. Since the roof consists of multiple distinct planes, when sketching each area, use clear and distinguishable 2D shapes like rectangles or squares.

Drawing your sketch to scale is not necessary. A basic representation of the roof will be sufficient to help you label each plane while taking measurements. Don’t worry about incorporating perspective to account for the roofing pitch. Simply draw the roof as it would appear from an overhead view.

Step 1: Set up the Ladder and Take Appropriate Safety Precautions

Working at heights can be dangerous. Before starting, make sure to set up the ladder on level ground with its base extending at least three feet (0.91 meters) away from the edge. This will provide a stable foundation for climbing. It is essential to have a second person on the ground to hold the ladder and be ready to call emergency services in case of an accident.

To prevent accidents or injuries, use fall prevention equipment such as a harness or a shock absorption lanyard. Maintain three points of contact by keeping your tape measure, notepad, and pencil in your pocket while climbing the ladder. Wearing closed-toe shoes with good traction will also improve your stability on the roof.

Step 2: Measure and Calculate the Square Footage of Each Plane

As you ascend to the top of the roof, ensure that the sketch of the roof in your notepad aligns with your position. This will ensure accurate labeling of each plane. Lay your measuring tape along the length of the plane and record the measurement in the appropriate location in your notepad. Then, extend the measuring tape across the width to determine the corresponding measurement.

To measure from the peak to the edge, position your feet at the top of the roof and extend the measuring tape downwards. Record the measurements from the exact peak to the edge.

If you need to measure along the peak, start by placing the tape at the edge of one side of the roof and run it along the peak.

Repeat this measurement process for both the length and width of the roof, and then descend from the roof using the ladder (with a partner holding it steady). Utilize these measurements to calculate the square footage for each roof plane. Keep in mind that some roof planes may have shapes other than rectangles or squares, such as trapezoids or triangles. Below are the formulas to calculate the surface area for rectangles, squares, and trapezoids.

Area of a rectangle or square:

A = L x W

Area = Length x Width

Example: 20 feet x 10 feet = 200 square feet

Area of a trapezoid:

A = [(B1 + B2) x H] / 2

Area = [(Top + Bottom) x Height] / 2

Example: [(5 feet + 10 feet) x 6 feet] / 2 = 45 square feet

Area of a triangle:

A = (B x H) / 2

Area = (Base x Height) / 2

Example: (5 feet x 4 feet) / 2 = 10 square feet

Use the total square footage of your roof to calculate its area after you’ve calculated each plane. Add up the areas of each plane to get the total roof square footage.

Step 3: Use the Square Footage to Calculate the Roofing Squares

After obtaining your measurements, it is necessary to convert the square footage. This is because shingle packages are commonly specified to cover approximately 1/3 of a roofing square. A roofing square, in the context of roofing, refers to an area of 100 square feet (9.3 square meters).

To convert your total square footage into roofing squares, you can utilize a roofing square calculator or simply divide the measurement by 100. For instance, if your roof measures 1,987 square feet, it is equivalent to 19.87 squares or rounded up to 20 squares.

Be sure to perform the conversion accurately to ensure you acquire the appropriate quantity of shingles for your project.

Step 4: Determine the Number of Shingle Bundles Required

The next step is to determine the number of bundles required for your roofing project. Typically, a bundle of shingles covers approximately one-third of a roofing square. Calculating the number of bundles needed is straightforward: multiply the number of roofing squares by three. For example, if your roof area is equivalent to 20 roofing squares, you will require approximately 60 bundles.

Additionally, the roofing square measurement can be used to determine the amount of roofing material needed. The material is available in rolls weighing 15 or 30 pounds, used to cover the roof shingles. A 30-pound roll covers 2 squares, while a 15-pound roll covers 4 squares. If you are using a 5-pound roofing felt, you can calculate the number of rolls required by dividing the number of roofing squares by four. On the other hand, if you are using a0-pound roofing felt, divide the number of roofing squares by 2 to determine the number of rolls needed.

Using these calculations will help you accurately estimate the amount of roofing material necessary for your project.

Step 5: Add 15 Percent to Account for Waste

You will likely come across roof angles with irregular shapes, which may require modifications to the tiles to fill the gaps. A few shingles in a package or two may be bent or cracked and unsuitable for use. Additionally, DIYers should anticipate some mistakes as not all cuts will be perfect. To accommodate these possibilities, it is recommended to have an extra 15 percent of the material. For example, if you need 50 bundles to cover the entire roof surface, you would multiply 50 by 1.15, resulting in a total of 57.5 bundles. Rounding up to the nearest whole number, you would need a total of 58 bundles of shingles for your roof.

Final Thoughts – How to Measure a Roof for Shingles

Even if you are simply ascending the roof to take a few measurements, there is still a risk of injury and other hazards. Accidental falls can result in injuries and fatalities, making them one of the most common accidents in both workplace and home settings. Working at heights poses inherent dangers.

If you’re not comfortable or experienced with measuring your roof for shingles, it’s highly recommended to seek the assistance of roofing professionals. All Star Roofing, located in Tampa, FL, has over 60 years of experience in the roofing industry. Their team of skilled experts can accurately measure your roof, ensuring precise calculations and a successful roofing project. 

Contact All Star Roofing today for a reliable and professional roof measurement service. Your safety and the longevity of your roof are their top priorities.

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