Shingles come in many shapes, sizes and designs. The most common types are asphalt shingles, which are packaged, stacked and sold as bundles. However, there are also cedar shake, aluminum shingles, plastic shingles and many other varieties. The one thing all shingles have in common is that bundles converted to squares (generally three bundles of shingles to a square) determine roofing coverage. Using a simple math formula, anyone can convert the square footage of a roof into the amount of squares needed for a cost estimate.
Measure the garage roof to determine how many squares you will need for coverage. Measure the length and the width of the garage roof. Any additions like overhangs or attached carports must also be measured.
Calculate the square footage by multiplying the width by the length. For example, a 20 foot long by 15 foot wide section will come to 300 square feet. Add the square footage together from all of the areas measured to get total square footage. This is the figure you will use for a shingle estimation.
Convert bundles of shingles into squares. Three bundles are equal to one square. Each square equates to 100 square feet. In the previous example, three squares, or 300 square feet, of shingles will be needed to cover the garage roof. After calculating the square footage needed, always add in an extra 10 percent to the total for shingle breakage.
Call around for the best estimate of shingle prices using the amount of squares calculated. Home improvement stores and building supply shops have a wide variety of shingles to choose from.