If you are planning to replace or repair your roof, you need to know its size and shape. Measuring a roof is not as hard as it may seem, but it does require some basic math and safety precautions. In this article, we will show you how to measure a roof step by step, and how to estimate the amount of materials you will need.
What You Will Need
To measure a roof, you will need the following tools and equipment:
- A measuring tape
- A ladder
- A level
- A calculator
- A notebook and a pen
- A sketch of your roof
Step 1: Sketch Your Roof
The first step is to draw a simple sketch of your roof on a piece of paper. You don’t have to be very accurate, but you should include the main features of your roof, such as the ridge, the eaves, the valleys, the hips, the gables, and any dormers, chimneys, or skylights. Label each section of your roof with a letter or a number, and mark the dimensions of the base of your house.
Step 2: Measure the Length and Width of Each Section
The next step is to measure the length and width of each section of your roof. You can do this from the ground or from the roof, depending on your preference and safety. If you measure from the ground, you will need to use a ladder to reach the eaves and the ridge of your roof. If you measure from the roof, you will need to use a level to find the horizontal and vertical distances.
To measure the length and width of each section, follow these steps:
- Hook your measuring tape to the edge of the eave or the fascia board, and extend it along the bottom of the roof section. Record the measurement in your notebook.
- Hook your measuring tape to the edge of the eave or the valley center, and extend it up to the ridge of the roof section. Record the measurement in your notebook.
- Hook your measuring tape to the edge of the rake or the gable end, and extend it along the side of the roof section. Record the measurement in your notebook.
- Repeat these steps for each section of your roof, and write down the measurements on your sketch.
Step 3: Calculate the Pitch of Each Section
The pitch of a roof is the angle or slope of the roof, expressed as a ratio of the rise (vertical distance) to the run (horizontal distance). For example, a pitch of 4/12 means that the roof rises 4 inches for every 12 inches of horizontal distance. The pitch of a roof affects the amount of materials you will need, as well as the difficulty and cost of the installation.
To calculate the pitch of each section of your roof, follow these steps:
- Place a level against the roof a few feet away from the edge, and adjust it until the bubble is centered.
- Measure the distance from the end of the level to the surface of the roof. This is the rise of the roof.
- Divide the rise by the length of the level. This is the pitch of the roof.
- Repeat these steps for each section of your roof, and write down the pitch on your sketch.
Step 4: Find the Area of Each Section
The area of a roof is the amount of surface that the roof covers, measured in square feet. To find the area of each section of your roof, you will need to use some geometry formulas, depending on the shape of the section. Here are the most common formulas you will need:
- For a rectangle or a square, multiply the length by the width.
- For a triangle, multiply the base by the height, and divide by 2.
- For a trapezoid, add the bases, multiply by the height, and divide by 2.
To find the area of each section of your roof, follow these steps:
- Identify the shape of the section, and choose the appropriate formula.
- Plug in the measurements of the length, width, base, and height into the formula, and calculate the area.
- Repeat these steps for each section of your roof, and write down the area on your sketch.
Step 5: Adjust the Area for the Pitch
The area that you calculated in the previous step is the area of the roof in a flat plane. However, since your roof is sloped, you need to adjust the area to account for the pitch. To do this, you will need to use a pitch multiplier, which is a factor that increases the area based on the pitch. You can find the pitch multiplier for your roof using a table, a chart, or a calculator.
To adjust the area for the pitch, follow these steps:
- Find the pitch multiplier for each section of your roof, using the pitch that you calculated in step 3.
- Multiply the area of each section by the pitch multiplier, and round up to the nearest whole number. This is the adjusted area of each section.
- Repeat these steps for each section of your roof, and write down the adjusted area on your sketch.
Step 6: Add Up the Total Area
The final step is to add up the adjusted area of all the sections of your roof. This is the total area of your roof, measured in square feet. To make it easier to order materials, you can convert the total area into roofing squares, which are units of 100 square feet. To do this, simply divide the total area by 100, and round up to the nearest whole number.
To add up the total area, follow these steps:
- Add up the adjusted area of all the sections of your roof. This is the total area of your roof in square feet.
- Divide the total area by 100, and round up to the nearest whole number. This is the total area of your roof in roofing squares.
Conclusion
Now that you know how to measure a roof, you can estimate the amount of materials you will need for your project. You can also use the measurements to get quotes from roofing contractors, compare prices, and budget accordingly. Remember to always follow safety precautions when measuring a roof, and to account for some waste and extra materials when ordering.