A roofer measuring a tiled roof.

How to Calculate the Size of My Roof

Knowing the roof’s square footage is an essential part of any roofing project you have coming up as it will help you determine how much roofing it may cost to have your roof repaired. However, there are a few considerations to keep in mind when you need accurate roof measurements. 

If you don’t plan on using a roofing contractor for this step, read about the intricacies of roof measurement estimates in our guide below. You will learn how to get accurate roofing measurements of your home’s roof. 

A benefit Legacy Roofing offers you is our Online Roof Estimate Tool. We encourage you to try this first before investing the time and energy into DIY options. 

Understanding Roof Shapes and Terms

Before we dive into the nitty gritty of getting an accurate measurement of your roof, we will first give you a quick 101 on the most common roof shapes and terms. Knowing this basic knowledge will help you measure even the most complex roof. 

Roof Shapes

  1. Gable Roofs: This is the most common type of home roof shape, which has two sloping sides that meet in the middle in triangular form. This roof shape is often seen in traditional-style home roofing, cottages, and barns. 
  2. Hip Roof: This style of roof has slopes on all four sides of the home’s exterior walls. The slopes meet at a ridge in the middle of the roof and are common in bungalows, ranch-style homes, and contemporary-style homes. 
  3. Flat Roof: Flat shapes have no slope and are horizontal. These types of roofs are common in modern homes, apartment buildings, and in commercial roofing

Key Terms Related to Roof Measurement

  1. Eaves: A horizontal edge of a roof that hangs off the roof over the home’s exterior walls. The purpose of eaves is to provide a horizontal runoff of water, protecting the home’s structure while also contributing to its aesthetics. 
  2. Ridges: The highest point where the roof surfaces meet, typically running horizontally along the top of the roof. Ridges maintain the structure of the roof and ensure ventilation. 
  3. Valleys: The V-shaped, inward slope of two roof planes promotes appropriate flashing and sealing, preventing leaks. 
  4. Pitch: The pitch is the steepness or angle of a roof’s slope that affects water runoff, snow capacity, the aesthetic appeal.
  5. Dormers: Small structures on the roof, projecting from the slope, creating a larger roof that includes a window. Dormers provide additional space and natural light to upper levels. 
  6. Skylights: Fixed or operable windows installed on the roof to allow natural light into the interior space. 

Tools and Materials Needed 

The tools and materials needed for measuring your roof’s square footage include: 

  • Measuring tape
  • Roofing square
  • Ladder
  • Calculator
  • Pen and paper
  • Smartphone or digital camera
  • Safety harness and anchorage system
  • Roof boots or roofing shoes
  • Gloves
  • Safety glasses 
  • First aid kit 
  • Roofing buddy

Roof Size Calculator Process: How to Measure Your Roof

Now that you know some of the common terms, and roof shapes, and we have all our tools and materials required to measure your roof, you can set off to work to measure the roof area. Follow our easy step-by-step guide below and be sure to call a roofing contractor for help if necessary. 

1. Prepare the Area

Start by clearing the roof of any debris like leaves, dirt, and twigs. Debris can often result in an incorrect roofing measurement. 

Make sure that the weather conditions are not wet, icy, or windy. Set up safety precautions, use a sturdy ladder, and wear a safety harness to prevent slipping and falling as you work. 

2. Choose Measurement Method

When choosing the measurement method, you get to choose from two options; manual or digital. 

  • Manual: Using a tape measure to measure each section of the roof. This method is cost-effective but can be time-consuming.
  • Digital: Provides accurate roof measurements and eliminates the need for physical access to the roof. Most digital methods offer 3D modeling and estimates, though the use of these methods usually costs more than manual options. 

The method you choose will depend on what is readily available and affordable to you. We recommend reaching out to a roofing contractor if you want the most accurate measurements of your roof. 

3. Measure the Length and Width

The way you measure your roof will depend on its shape: 

  • Gable Roof: Measure the length and width of each rectangular section separately. Start at the eaves and measure along the slope to the ridge for length, and from one end to the other for width.
  • Hip Roof: Divide the roof into separate sections and measure the length and width of each section individually. Take diagonal measurements for accuracy in irregularly shaped sections.
  • Flat Roof: Measure the length and width of the entire roof surface in one go, ensuring to account for any protrusions or obstructions.

Be sure to use a measuring tape or roofing square for the most accurate measurements and measure from the same starting point. Also, take multiple measurements and average them for accuracy. 

4. Calculate Roof Area

Once you get your measurements, you will need to follow a simple formula to get the area. 

Area of your roof = Length x Width

For triangular sections: Area = 0.5 x Base x Height

Total Roof Area = Sum of all individual section areas

Be sure to break down each roof section into smaller sections when the roof is an irregular shape. 

5. Account for Pitch Factor and Overhangs

Be sure to measure the overhangs of the roof separately and subtract their area from the total roof area calculation. Do the same for dormers and skylights. 

Contact Legacy Roofing for Your Roofing Needs

Do you need a roof repair or roof replacement? Whether you just need to measure the square footage of your roof or need help with other roofing needs, you can count on us for effective and experienced assistance. Call Legacy Roofing today. We are here to help.

Schedule an appointment or inspection with Legacy Roofing today!

If you would like Legacy Roofing to inspect your roof and offer a free estimate, please call us, or fill out the contract form below. Legacy will send a trained estimator to inspect and offer an experts opinion on the size and scope of your job.

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Servicing All of Northern Arizona

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Legacy Roofing LLC - Prescott