How To Determine The Amount Of Roofing Shingles You Need

by | Oct 7, 2022 | roofing

roofingRoofs are a critical structural component of your home. A successful roof replacement project will require a significant investment in time and money. We recommend that you hire a professional roofing contractor to do the job properly.

Roofing Estimate

First, estimate the roof’s total surface area to determine how many shingles are needed. Measure the length and widths of all the roof planes, dormers included, to determine the required number of shingles. To calculate the square footage for each plane, multiply the width by the length. Then, add the square footage from each plane together to calculate the total roof area.

A shed roof, for example, just has a single roof plane. Just measure the length (A), width (B) and height (C):

The gable roof is made up of two planes. To get the square footage of each plane, multiply length (A), x width (B). Add the two planes together and you will get the total roof area.

Roof surfaces are measured in “squares”. One square refers to a 100-square-foot area of roof. Divide the 24,000 square foot total by 100 to find the squares of the gable roof. This gives you 240 squares, which means that you will need 240 squares to cover the roof. Three bundles are usually required for a typical shingle type, the three-tab or strip.

You will need the same amount underlayment for a new roof. In the above example of a gable roof, you would need to have 240 squares underlayment. Rolls of underlayment are usually 4×4 in square. For a total of 240 squares, 60 rolls would be required. If you apply shingles directly to an asphalt roof, no underlayment is required.

Trim allowances should be added to your material totals by 10%

If you have any questions regarding your estimate, contact a local roofing contractor in Florence SC. Many will give you a free estimate.

What’s the slope of the roofing system?

Also, you will need to determine the slope of your deck. This can be done by measuring the vertical rise of your deck over a 12-inch horizontal distance. If the rise is 4 inches, your roof slope will be 4 in 12. A roof slope is always expressed using the vertical rise and the horizontal run (12″) first.

What happens if your roof is steep?

An alternate method is required to measure steep roofs. Measure the length of your roof from the outside walls to the ridge. Next, place a rope on the ridge and mark each eave with it. This will provide the area’s width. This should be done for each section of the roof that has a horizontal ridge.

How about nails?

Also, you will need to decide how many nails you will need for the roof installation. You should generally use four nails per shingle. This would be 320 nails per square for regular three-tab shingles. Six nails per shingle (480 nails per square) are needed for high winds areas and when shingles are being applied on a mansard.

This calculation is based on 80 squares of shingles. Different styles of shingles might require more or fewer nails per shingle, and may have more or lesser than 80 shingles per square. For the right nailing pattern, refer to the instructions on the shingle wrappers.

You can purchase nails by the pound. Ask your dealer to determine the right amount of nails needed for your roof size and length. To determine how much drip edge is required, measure the lengths of the eaves and rakes.

Call Florence Roofing Experts now if you need the help of a roofing contractor.

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Florence Roofing Experts
Florence, SC 29501
(843) 773-4787

Serving: Lake City, Marion, Darlington, Hartsville, Florence

Contact Us

Florence Roofing Experts
Florence, SC  29501
(843) 503-2348

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