How to Measure a Roof for Shingles (In 12 Steps)

Whether you’re replacing old shingles or installing a new roof, accurate measurements are crucial. Ensuring you have the correct amount of materials not only saves you time and money but also prevents any delays in your project. Measuring a roof for shingles might seem daunting at first, but by following a systematic approach, you can simplify the process. In this guide, we will walk you through how to measure a roof for shingles, including:

• Understanding the basics
• Gather tools and materials
• Measure exterior walls
• Measure roof overhangs
• Calculate roof area
• Measure roof pitch
• Calculate roof pitch factor
• Calculate adjusted roof area
• Account for roof features
• Calculate total number of shingles
• Add a waste factor
• Verify your measurements
• Purchase shingles

🤔 Understanding the Basics

Before diving into the measurement process, it’s important to understand some basic concepts and terminology related to roofing:

1. Square Footage: Roofing materials are typically measured in squares. One square equals 100 square feet.
2. Roof Pitch: The roof pitch is the slope of the roof, often expressed as a ratio (e.g., 4:12).
3. Roof Sections: Roofs can have multiple sections with different slopes, angles, and shapes.

Now, let’s break down the process into manageable steps.

1. Gather Your Tools and Materials

To measure your roof accurately, you’ll need the following tools and materials:

• Measuring tape (preferably 100 feet)
• Ladder
• Notebook and pencil
• Calculator
• Safety gear (gloves, helmet, harness)
• Roof pitch gauge or smartphone app for measuring pitch
• A helper (optional but recommended)

2. Measure the Exterior Walls

Start by measuring the perimeter of your house at ground level. This will give you the overall footprint of your roof. Follow these steps:

1. Use your measuring tape to measure the length and width of each exterior wall.
2. Record these measurements in your notebook.
3. If your house has an irregular shape, break it down into smaller sections and measure each section separately.

Example:

• Front Wall: 40 feet
• Back Wall: 40 feet
• Left Wall: 30 feet
• Right Wall: 30 feet

Total Perimeter: (40 + 40 + 30 + 30) = 140 feet

3. Measure the Roof Overhangs

Roof overhangs are the parts of the roof that extend beyond the exterior walls. To account for these, measure the overhang distance on all sides of the house:

1. Use your measuring tape to measure the overhang distance (e.g., 2 feet).
2. Multiply this distance by the total perimeter of the house.

Example:

Overhang Distance: 2 feet

Total Perimeter: 140 feet

Total Overhang: 2 feet × 140 feet = 280 square feet

4. Calculate the Roof Area

Next, calculate the total roof area by adding the footprint area to the overhang area. Use the following formula:

Total Roof Area = (House Length × House Width) + Total Overhang

Example:

House Length: 40 feet

House Width: 30 feet

Footprint Area: 40 feet × 30 feet = 1,200 square feet

Total Roof Area: 1,200 square feet + 280 square feet = 1,480 square feet

5. Measure the Roof Pitch

The pitch of your roof affects the actual surface area you need to cover with shingles. Roof pitch is typically expressed as a ratio of vertical rise to horizontal run (e.g., 4:12). To measure the pitch:

1. Place your pitch gauge or smartphone app on the roof surface.
2. Record the pitch ratio.

Example:

Roof Pitch: 4:12 (this means for every 12 horizontal feet, the roof rises 4 feet)

6. Calculate the Roof Pitch Factor

The roof pitch factor is a multiplier used to adjust the roof area calculation based on the pitch. Use the following chart to find your pitch factor:

Pitch RatioPitch Factor3:121.034:121.065:121.086:121.127:121.168:121.20

Example:

Roof Pitch: 4:12

Pitch Factor: 1.06

7. Calculate the Adjusted Roof Area

Multiply the total roof area by the pitch factor to get the adjusted roof area:

Adjusted Roof Area = Total Roof Area × Pitch Factor

Example:

Total Roof Area: 1,480 square feet

Pitch Factor: 1.06

Adjusted Roof Area: 1,480 square feet × 1.06 = 1,568.8 square feet

8. Account for Roof Features

Your roof may have additional features such as dormers, valleys, and hips. These features can affect the total area and the amount of shingles needed. Measure and account for these features as follows:

1. Dormers: Measure the length and width of each dormer and calculate its area. Add this to the total roof area.
2. Valleys: Measure the length of each valley and multiply by the valley width to get the valley area. Add this to the total roof area.
3. Hips: Measure the length of each hip and multiply by the hip width to get the hip area. Add this to the total roof area.

Example:

Dormer Area: 50 square feet

Valley Area: 30 square feet

Hip Area: 20 square feet

Total Additional Area: 50 + 30 + 20 = 100 square feet

Adjusted Roof Area with Features: 1,568.8 square feet + 100 square feet = 1,668.8 square feet

9. Calculate the Total Number of Shingles

Shingles are typically sold in bundles, with three bundles covering one square (100 square feet). To calculate the total number of bundles needed:

1. Divide the adjusted roof area by 100 to get the total squares.
2. Multiply the total squares by 3 to get the total number of bundles.

Example:

Adjusted Roof Area: 1,668.8 square feet

Total Squares: 1,668.8 / 100 = 16.688 squares

Total Bundles: 16.688 × 3 = 50.064 bundles

Since you can’t purchase a fraction of a bundle, round up to the nearest whole number:

Total Bundles Needed: 51 bundles

10. Add a Waste Factor

To account for waste due to cutting and fitting shingles around edges, valleys, and hips, add a waste factor. Typically, a 10% waste factor is recommended:

Waste Factor: 10%

Total Bundles with Waste: 51 bundles × 1.10 = 56.1 bundles

Round up to the nearest whole number:

Total Bundles Needed with Waste: 57 bundles

11. Verify Your Measurements

Before making any purchases, double-check all your measurements and calculations. It’s always a good idea to have someone else review your work to ensure accuracy.

12. Purchase Your Shingles

With your final number of bundles calculated, you can now purchase your shingles. Be sure to buy from a reputable supplier and consider ordering a few extra bundles to account for any unforeseen issues during installation.

🙌 Master Your Roofing Project with Kraft Roofing

Accurately measuring your roof for shingles is a crucial first step in any roofing project, whether you’re a DIY enthusiast or hiring a professional. Taking precise measurements ensures you order the correct amount of materials, which can save you time and money. By following the steps outlined in this guide—such as sketching your roof, calculating the area, factoring in roof pitch, and accounting for waste—you can approach your roofing project with confidence. Investing time in careful measurement is an investment in the durability and success of your roof. If you need expert assistance, don’t hesitate to contact Kraft Roofing. Our experienced team is here to provide guidance, accurate measurements, and professional roofing solutions tailored to your needs. Reach out to us today to ensure your roofing project is smooth and successful.