Before you can install cedar shingles on the roof of your house, you'll need to calculate how many shingles it will take to cover your roof effectively. Cedar shingles are often sold by the bundle, and beginners may not understand how to figure out the number of bundles they will need for a given project. A bit of measuring and math will help you to figure out how many bundles you'll need to shingle your roof.
Measure the width and height of one section of the roof, and multiply the numbers together to get the square footage of that section. Repeat with the rest of the sections and add the products together to get the square footage of the entire roof.
Divide the square footage of the roof by 100 to get the number of "squares" needed. (A "square" of shingles covers 100 square feet of roof.)
Look at the bundle (package) of cedar shingles to see how many bundles it takes to make up one square of shingles. It will usually take three or four bundles to make up one square.
Multiply the value in Step 2 by the value in Step 3 to determine how many bundles of shingles you will need. Round this number up if you need to buy whole bundles.
This article applies to shingling a roof using the typical amount of exposure (about five inches). If you are using a much larger or much smaller amount of exposure, adjust the calculations accordingly.
Round up slightly to take into account shingles that might split or break during the shingling process.