Quantity of Squares in Shingle Bundles

Installing a new roof is a major undertaking that requires careful planning and material calculations. One of the most critical steps is determining the total number of shingle bundles needed to complete the job. This depends on accurately measuring the roof's square footage and understanding how shingle bundles translate into coverage area.

Shingle bundles contain a standardized amount of individual shingle pieces that cover a set square footage when installed. By learning the relationship between bundle quantities and squares, you can estimate material requirements and avoid costly overages or shortages.

Breaking Down a Shingle Bundle

Shingle bundles are packaged groups of individual shingle pieces that contractors use for installation. The number of pieces per bundle depends on the shingle type:

• 3-tab shingles - 24-36 pieces per bundle
• Architectural shingles - 14-24 pieces per bundle

Although 3-tab shingles contain more individual pieces, each architectural shingle is larger in size. This results in an equivalent amount of total coverage per bundle between the two styles.

Standard Coverage Amount

The key specification to understand is the coverage amount per bundle. Most shingle bundles cover approximately 33-35 square feet of roof area when installed. This square footage accounts for the recommended overlap required between shingles.

Some specialty shingle styles may deviate slightly from the standard 33-35 square foot coverage. However, the vast majority of popular shingle brands and types adhere to this sizing convention.

Verifying Bundle Coverage

To verify the coverage for a particular shingle product, check the manufacturer's specifications. They should provide the square footage that each bundle covers when installed according to their guidelines. If you cannot find this info, reach out to the manufacturer directly for technical support.

You can also double check by measuring the dimensions of a shingle piece and multiplying the total number of pieces per bundle. This should give you the approximate bundle coverage. Comparing your manual calculation to the advertised coverage helps identify any inconsistencies.

Calculating Total Roof Square Footage

With the standard bundle coverage in mind, the next key step is calculating the total square footage of your roof. begin by measuring the length and width of each roof section or plane:

• Length x Width = Square Footage of Roof Section

Account for all sloped and vertical areas that will be shingled, including irregular sections like dormers, hips, valleys, and roof transitions. Drawing a roof plan or using aerial imagery helps ensure accuracy.

Add together the square footage of every measured section to get the total roof area. This must reflect the entire continuous shingled surface. Don't omit critical details that add up.

Dealing With Complex Roof Shapes

For roofs with complex geometries, consider investing in a professional roof measuring service. They use aerial photography and 3D modeling software to digitally calculate precise square footages, even for challenging roofs. The small fee for accuracy could prevent major mistakes.

If going the DIY route, take your time. Break the roof into logical rectangular sections that you can easily measure. Triple check your math, and have someone review to verify no areas are missing.

Converting Roof Dimensions

When measuring roof dimensions, make sure to convert any feet and inches into a decimal square footage format. For example, a roof section measuring 32 feet and 4 inches long by 24 feet and 8 inches wide would be:

Length: 32.33 ft (32 + 4/12 = 32.33 ft) Width: 24.67 ft (24 + 8/12 = 24.67 ft) Square Footage: 32.33 x 24.67 = 798 square feet

Avoid rounding until you have your final total square footage calculated. The small decimals make a difference.

Determining Number of Bundles

With accurate square footage and the bundle coverage specifications, you can now estimate the required number of shingle bundles:

Total Square Footage / Coverage Per Bundle = Total Bundles Needed

If the total roof area is 3,000 square feet, and each bundle covers 35 square feet, you would need approximately 86 bundles (3,000 sq ft / 35 sq ft per bundle = 85.71 bundles).

Round up to the nearest whole bundle as you'll want extra materials. Don't round down and risk running short on shingles mid-project.

Adding a Waste/Overage Factor

It's recommended to add a 10-20% overage factor to account for:

• Cutting loss around irregular edges and protrusions
• Manufacturing defects in shingles
• Minor measurement inaccuracies
• Inclement weather damage

For a 3,000 square foot roof with a 15% overage, the estimate would be:

3,000 sq ft x 1.15 = 3,450 adjusted sq ft 3,450 sq ft / 35 sq ft per bundle = 98 bundles

Having surplus bundles leftover is ideal compared to running short on materials. Plan for waste.

Calculating Starter Courses

Don't forget to account for starter strip shingles along eaves and rakes. About 20 linear feet of starters are needed per 100 square feet of roof. Determine your linear footage of starters and divide by 20 to get the estimated courses needed. Each starter course requires about 2 bundles.

Considerations for Specific Shingle Types

The standard 33-35 square feet per bundle is a reliable guideline for most common shingle styles. However, certain specialized products may deviate from this norm.

Architectural Shingles

Although architectural shingles are larger in size than 3-tabs, they still maintain a similar coverage ratio per bundle when following the manufacturer overlap recommendations.

If utilizing an increased exposure method, the coverage per bundle may be reduced. Always verify specifications.

Luxury Shingles

Premium luxury shingles, such as natural slate or shake replicas, sometimes provide less coverage per bundle. This is due to the increased material weight and labor involved. Reputable luxury brands still maintain coverage in the 30 square foot range per bundle.

Low-Profile Shingles

Certain low-profile shingles with reduced exposure heights can have up to a 10% increase in squares per bundle compared to standard products. This is attributed to decreased overlap requirements.

Regional Building Codes

Specific regional building codes may require elevated overlap amounts between shingles to withstand heavy winds, hail, snow loads and other weather. This would decrease the coverage per bundle. Consult local regulations.

The bottom line is to always reference the coverage charts for your specific shingle type and color. Never assume a blanket 36 square feet across different brands or styles.

Verifying Real-World Coverage

To validate coverage amounts, consider performing test installations before fully re-shingling:

Install a Few Bundles

Ask the roofer to install 2-3 bundles according to manufacturer specifications. Measure the area covered and compare to advertised square footage per bundle. Verify any discrepancies before continuing.

Rip Off Old Shingles

If replacing old shingles, have the roofer rip off a small section first. Count the courses removed and calculate the total square footage. Compare to how many bundles would be required to re-cover the area.

In some cases, doing the math ahead with individual shingles laid out on the ground can help identify coverage gaps before roof installation. This may be tedious but removes variables introduced by sloped roof planes.