How to Figure Out How Much Sheet Metal Is Needed for a Metal Roof

If you enjoy the sound of rain on a metal roof, you might want to apply sheet metal to your own roof.
Sheet metal comes in a variety of colors and styles.Sheet metal comes in a variety of colors and styles.
Sheet metal is an attractive roofing option that often outlasts other types of roofing materials such as asphalt or fiberglass shingles. One of the first steps to installing a metal roof is to determine the amount of sheet metal that you will need for the job. This calculation allows you to plan for materials and expenses associated with the project.

Step 1

Draw a simple sketch of your roof. Divide the drawing into rectangles and, if necessary, triangles.

Step 2

Climb onto your roof and measure its dimensions with a tape measure. You'll need to measure the length and width of the rectangular portions of the roof, as well as the base and height of any triangular sections. Write these measurements onto your sketch.

Step 3

Find the square footage of each section of the roof. For rectangular sections, multiply length times width. For triangular sections, multiply base times height and divide by 2. Add the square footage of each shape to find the total square footage.

Step 4

Determine the square footage of a piece of sheet metal by multiplying its length times its width. For example, if the sheet is 20 feet long by 2 feet wide, multiply 20 times 2 to get 40 square feet.

Step 5

Divide the total square footage of the roof by the square footage of a single piece of sheet metal. For example, assume that a roof contains 1,800 square feet of space and a piece of sheet metal has an area of 40 square feet. In this case, you would divide 1,800 by 40 to get 45. This means that you would need 45 pieces of sheet metal to cover the roof.

Step 6

Multiply the total amount of sheet metal by 0.08 to 0.10 and add the product to the total amount to account for waste. In this example, you could multiply 45 times 0.10 to get 4.5. Then add 4.5 to 45 to get 49.5 pieces of sheet metal.

Things You Will Need

  • Pencil and paper
  • Ladder
  • Measuring tape

About the Author

Charlotte Johnson is a musician, teacher and writer with a master's degree in education. She has contributed to a variety of websites, specializing in health, education, the arts, home and garden, animals and parenting.