How many bundles in a square of shingles

It typically takes three bundles of standard three-tab asphalt shingles to cover one square on a roof. Therefore, a 40-square roof would require approximately 120 bundles of shingles. A “roof square” is equal to 100 square feet, so each bundle covers roughly 33 1/3 square feet.

The Owens Corning website notes that it is common to add 10 percent to an estimate for shingles to allow for trimming. If shingles get trimmed at the edge, bottom or top of a roof, three bundles would cover less than one square. Thus, a 40-square job would actually dictate 132 bundles, including an extra 12 bundles for trimming allowance.

One of the hardest home improvement jobs any homeowner can undertake is roofing projects. It is easy to see why so many leave this up to professional roofing contractors.

While this does make a lot of sense, there can still be a good reason to know how many roof shingles you need for your roof.

So you can obtain a good understanding of what you will need, here is all you need to know about
calculating the number of bundles and total shingles needed for your roof, regardless of who installs it.

How Many Bundles in a Square?

You will find roof shingles sold by the bundle and by the square. It takes a square of shingles to cover 100 sq. ft. of your new roof.

Shingles come pre-packed in either paper or plastic-wrapped bundles, and they design them to be an ideal weight for one person to carry.

Using this method, if you opt for heavier duty shingles such as you may need in high wind areas, you will need more bundles per square, because of the weight.

How Many Squares are in a Bundle of Shingles?

The most common you find apply to three-tab shingles and take three bundles of shingles for each square. It can also include some of the lighter weight laminated shingles.

Once you look at the more substantial three-tabbed variety, these require four per square and sometimes possibly five to cover the same square.

Once you have a three-bundle pack to cover a square, you will have 29 x 12 inches by 36-inch standard-sized shingles per bundle.

The hardest part is how you determine the number of bundles it requires you to order to cover all your roof areas.

You will find two methods to calculate your roof size and comprise the measurement method and the sheet-count method. You can find a less common method used for when you calculate bundles for shingles, which will lie over old shingles.

Once you have these measurements, you need to allow for wastage, your starter shingles, and the extra you need for hip and ridge caps.

How Many Bundles of Shingles Do I Need?

Here is a breakdown of the calculation methods to determine the total square footage of your roof.

How to Measure a Roof for Shingles

The most accurate calculation of the number of shingle bundles needed is climbing up to the roof and measuring each roof plane on the roof.

If all roof planes are rectangular, you can quickly multiply their length by the width of each plane. Add them together, and you have your square footage for the whole roof.

It does become more difficult when you have a complicated roof, and the planes are of different sizes.

In some cases, for safety reasons, it may be necessary to take measurements from the ground.

Measure the length of the building and estimate the possible overhang of the rake edge. For widths, climb up a ladder and measure from the roof ridge to the eaves with a rigid tape.

Sheet-Count Method

If you have sheathing, which is still exposed, this means it can be a suitable alternative to the measurement method.

It allows for a fast calculation, and you can do it from your yard. However, it is only suitable for roofs sheathed with 4-ft. by 8-ft. structural panels.

Each of these structural panels will be 32 sq. ft. and counting panels from the yard is straightforward.

If you are using three bundles to a square, calculating bundle numbers is simple. Each of your bundles can cover 33.3 sq. ft. of your roof area, which is close to the sheet coverage area of 32 sq. Therefore, order one bundle for every sheet of roof sheathing you have.

With other bundle counts per square, divide the sheet number by three and come up with the number of squares you need to cover your roof.

You find this crude method works because three sheets of sheathing are roughly the size of one square (100 sq. ft.).

How Many Extra Shingles Do You Need?

If you order shingles for the precise size of the roof, you won’t have enough. You have to account for starter shingle courses that run across your eaves and possibly the rakes. In your additional calculation, you also need to allow for cap hips and ridges.

You also create waste once you begin cutting, and in the areas of rakes, walls, chimneys, and valleys, you do need to cut for an exact fit of the asphalt shingles.

Some cutoffs may be large enough for some of your starter shingles or other areas, yet most will be waste.

When ordering for wastage, around one percent is sufficient for a simple roof, yet if you have a complex roof or you have a steep roof slope, and some shingles may slide off, you can increase this to around five percent wastage.

It is hard to calculate the number of squares this amounts to and can depend on your installation crew.

Extra valley roofing material is one area where the method differs. You have woven or cut, yet both take the same number of shingles.

Starter shingles can comprise 3-tab shingles, or you can use leftovers from a previous job. Rake edges don’t necessarily require starter shingles fitting, yet many roofers do this for a more delightful finish.

Hip and ridges are covered by cap shingles, which are one square foot in size. It is possible to cut standard shingles to make these caps, or it is possible to use leftovers if they are large enough.

On many occasions, for roofs that use laminate or multi-cutout, you may need to use specifically manufactured hip-and-ridge shingles. Calculating this just requires you to measure ridge and hip lengths and divide by 35.

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