How to Calculate Squares of Shingles

Estimating the amount of shingles for a roof is designated by a square. A square, when used in roofing terms, is equal to 100 square feet, or a 10-foot by 10-foot area. This is the exposed portion of the shingles that you can see from the ground. There are typically three bundles of shingles for every square of roofing. Roofing is sold in paper-covered packages, by the bundle. When ordering shingles, it will be a good idea to over-order by at least two extra bundles.

Difficulty: Moderate

Instructions

Things You'll Need:

• Ladder
• Tape measure

1. Set the ladder in an accessible area to gain access to the roof. If you are uncomfortable with climbing onto the roof, have someone help you.

2. Measure the length of the roof from one end to the other with the tape measure. Run the tape up the width of the roof. Area of the roof is found by multiplying the length times the width (A = L x W). In an example, a basic two-sided gable roof has the dimensions of 45 feet long by 20 feet wide.

3. Multiply 45 feet times 20 feet to find one side of the roof area. The one side is equal to 900 square feet. Double this area for the total of the complete roof, which is equal to 1,800 square feet.

4. Divide 1,800 square feet by 100 square feet to find that 18 squares of shingles will cover the roof. Multiply the 18 squares by 3 bundles per square to find that 36 bundles will be needed to shingle the roof area.

5. Add two extra bundles for a total of 38 bundles. These two extra bundles will be used for the first course of the lower edge of roofing and for the ridge cover. Typically the ridge is covered by cutting the three tab shingles into individual pieces. This single tabs are then nailed at the roof's peak onto the adjoining roof shingles (See Resources).

Tips & Warnings

• Break down odd-shaped roofs into smaller squares for calculating the area. It is better to over-figure the amount of shingles then to under-estimate the complete amount.
• Be aware or your surroundings whenever climbing onto any roof structure.

References

• Roofing

Resources

• Estimating Shingles for a Roof