The simple way of measuring your roof for shingles is to measure your roof’s total surface area. To do this, multiply the length by the width of each plane on your roof to get your square footage. You then need to add the square footage of each plane together.
This then forms the basis of knowing how many shingles you’ll need.
Sounds simple, right? Well, knowing how to measure a roof for shingles the right way is a little bit more than this.
In this guide, we’ll show you the steps necessary for measuring a roof structure for a new shingle installation.
But, we give you a get-out-of-jail card at the end, so it’s worth sticking with us…!
Before You Begin….
First things first — you need to prepare and make sure you have everything you need to tackle this project. This not only includes the tools and equipment required, but also a good understanding of the process that lies ahead.
While the task might seem daunting at first, you’ll find that it’s perfectly manageable as we break it down into smaller, more digestible steps.
Why Accuracy Matters
Roofing materials are expensive, and shingles are no exception — the roof shingle repair cost in Wisconsin can easily run you hundreds of dollars.
This makes accurately measuring your roof essential so you purchase the right amount of shingles and avoid overspending.
Moreover, an accurate measurement also guarantees a proper fit for your shingles, preventing any potential issues and ensuring the longevity of your roof. The last thing you need is for shingles to come loose due to a bad fit and for your whole roof to deteriorate as a result.
Tools Required
Now you’ve got your accuracy hat on, here are the essential tools you’ll need to get measuring:
- Tape Measure: A 25-foot long tape measure should suffice for most residential roofs. This will allow you to get precise measurements of your roof’s length and width.
- Ladder: You’ll require a sturdy and reliable ladder to safely reach the top of your roof. Make sure that the ladder you use is appropriately sized for your house.
- Calculator: Handy for quick calculations and an essential tool for determining the total square footage of your roof (even if you’re excellent at mental arithmetic!)
- Notepad and Pen: Use these to jot down measurements as soon as you have them. This will help prevent any confusion later on.
- Angle Finder: Also known as a pitch gauge, this tool helps determine the slope of your roof, which impacts the total square footage.
Hold up! We know you’re about to skip ahead and think you don’t need these tools. If we had a dollar for the amount of times clients have forgotten their roof’s surface area…
Safety Considerations
Before you even think about setting foot on your roof, know that you’ll be working on one of the most riskiest areas of your home.
According to a study by the National Safety Council, falls remain a leading cause of unintentional injury deaths globally. Therefore, being adequately prepared and cautious can help minimize your risk when doing any kind of work on your roof.
No DIY task is worth risking your safety and well-being, so consider the following safety guidelines:
- Personal Protective Equipment (PPE): Ensure you have the right protective gear, including a sturdy pair of non-slip shoes or boots, gloves, and safety glasses. As an additional safeguard, consider using a safety harness to prevent accidental falls.
- Weather Conditions: Always check the weather forecast before starting your job. Avoid working on your roof during inclement weather conditions, particularly when it’s raining or windy, as this can make the roof surface slippery.
- Ladder Safety: When using a ladder, make sure it’s in good condition and firmly secured at both the bottom and top. Always maintain a 3-point contact (two hands and a foot, or two feet and a hand) while climbing up or down.
- Get a Partner: Having an extra set of hands will help you do the job safely and easily, especially if you need someone to hold the ladder. Be sure to have someone else present when working on your roof, in case of any emergencies.
- Roof Condition: If it’s in poor condition or has loose shingles, it may not be safe to walk on.
If you’re in Wisconsin and the above sounds like too much like hard work before you’ve even started, please get in touch with us so we can remove the burden for you.
Here’s How to Measure a Roof for Shingles Step-By-Step
Ok, it’s time. Are you ready?
You’ve got the tools ready, you understand you need to be accurate, and you’re aware of the safety precautions.
Now walk through these steps on how to calculate the shingles for a roof you’ll need:
1. Preparation
Before starting the measurement process, ensure your safety equipment is properly fitted and in good working condition. Double-check your tool kit as well, making sure you have everything you need on hand. We know we’ve already talked about making preparations for the job and you’re probably eager to get started, but we can’t stress this enough — safety is paramount.
So, ensure that you have everything you need and take the necessary precautions.
You don’t want to spend more time up there than necessary, and going back and forth for anything that you might have forgotten will not only be a nuisance but potentially dangerous.
2. Measuring the Roof
When you’re ready to start, climb onto the roof using your ladder then measure the length and the width each plane of the roof using your tape measure (including dormers).
You also need to determine the pitch or slope of the roof as it affects the total square footage of your roof and how many shingles you need. The steeper the roof pitch, the more surface area it covers, and hence, the more shingles it requires.
Note that the pitch of the roof is the vertical rise of the roof for every 12 inches of horizontal run and you can use the angle finder to measure it:
- Set the angle finder onto the roof with one side parallel to the edge of the roof
- Adjust until it’s level
- Note down the reading in degrees immediately to prevent any confusion later on
Once you have all the measurements, get down to a safe location and put away all of your tools. It’s math time!
3. Calculating the Area
- Calculate the roof square footage of each plane by multiplying the length by the width
- Sum the area of all planes together to get the total area of the roof.
For example, if your roof has two identical planes that are each 15 feet by 20 feet, then the total roof area is:
2 * (15 ft. * 20 ft.) = 600 sq. ft.
Next, you need to determine the pitch factor of your roof (the number of square feet per lineal foot). To do this, use the formula Pitch Factor = (1/Pitch in Degrees) x 12.
For example, if your roof has a pitch of 6 degrees, your pitch factor would be 1/6 * 12 = 2.
This means that every inch of vertical rise equals 2 inches of horizontal run. You then multiply the number with your total roof area to get the final figure.
Working example: So, let’s say your roof has a pitch factor of 2 and an area of 600 sq. ft. We would then calculate the area as (2 * 600) = 1200 sq. ft.
5. How Many Bundles of Shingles Do I Need?
To determine the amount of bundles of shingles you need, consider that a standard pack of shingles covers approximately 33.3 square ft. So, it’s a simple matter of dividing the total roof area (including the pitch) by 33.3 to find out how many packs of shingles you need.
But, hold on — this isn’t the final number, so don’t go off buying anything yet until you’ve been through this entire guide!
If, at this point, you’re confused as to how many bundles you need, are in Wisconsin, and would like us to take on the project instead, click the button below to get in touch with our team.
6. Calculating Roofing Materials
Once you’ve determined the approximate number of shingle packs required, it’s time to consider other essential roofing materials:
- Roofing Underlayment: A layer of waterproof or water-resistant material installed directly onto your roof deck. The amount needed is equal to the total roof area.
- Drip Edge: This material is installed along the edge of the roof to ensure water drips away from the fascia and into the gutters. To calculate, you’ll need to measure the total length of your roof’s eaves (the horizontal edges) and multiply it by 2, as you’ll need drip edge on both sides.
- Roofing Nails: Typically, you’ll need 4 nails per shingle. However, for roofs with a steep pitch or in areas with strong winds, 6 nails might be required. Remember to include an extra 10% to account for potential loss or damage.
- Flashing: Flashing prevents water from seeping into the joints or valleys of your roof. It’s recommended to replace flashing whenever you get a new roof. Measure the length of the valleys and chimneys to estimate how much flashing you need.
- Ridge Cap Shingles: These are special shingles that cover the ridge of your roof. To calculate how many you need, measure the length of your roof’s ridges and hips.
- Roofing Cement: Useful for sealing any potential weak points where water might get in. It’s generally sold in tubes, and a few should suffice for most residential roofs.
- Ventilation: Adequate ventilation is essential to protect your roof from excessive heat and moisture. Various types of vents are available; the best choice depends on your roof’s design and local climate conditions.
7. Accounting for Waste
While you don’t want to spend more than you have to, you also don’t want to run out of materials halfway through your project.
However, roofing projects inevitably produce waste, which must be factored into your calculations to ensure accurate estimates. Waste could result from:
- Damaged shingles and underlayment
- Off-cuts
- Errors during installation
Typically, you can expect waste in the range of 10%-15% for simple roof designs. However, for more complex roofs with multiple valleys, dormers, or turrets, the waste factor could increase up to 20%.
To account for this, calculate 10%-20% of your total material requirements (including shingles, underlayment, and other roofing materials) and add this to your initial estimate. This will give you a more realistic idea of the total quantity of materials required.
Disposing of roofing waste should also be considered. Many towns and municipalities have regulations regarding the disposal of construction waste, so it’s essential to check local rules and regulations.
Measuring a Roof for Shingles by Roof Types
While the steps outlined above provide a comprehensive guideline for measuring a roof for shingles and calculating the material requirements for a general roofing project, it’s critical to note that this process can vary significantly depending on the type of roof.
You see, each roof type comes with unique design features that can influence the number of roofing squares and required roofing materials.
Let’s dive into the nuances and considerations for different roof types.
How to Measure a Gable Roof for Shingles
To calculate shingles for a gable roof, take the length and width of each plane of the roof, including any dormers. Add these areas together to get the total area. Adjust this figure for the pitch of the roof, then divide by 33.3.
So, for example, if your gable roof has two planes, each measuring 20 feet by 30 feet, with a pitched roof of 6/12 (meaning the vertical rise is 6 inches for every 12 inches of horizontal run), then the total area would be (2 * (20 ft. * 30 ft.) * pitch factor = 1200 sq. ft.
Dividing this by 33.3 would give you approximately 36 packs of shingles required.
How to Measure a Hip Roof for Shingles
To measure a hip roof for shingles, measure the length and width of each plane, including the triangular “hip” faces. Add these areas together, adjust for the pitch, then divide by 33.3 to determine the amount of shingles you’ll need for the project.
For example, if your hip roof has four planes, each measuring 20 feet by 30 feet, with a pitched roof of 6/12, then the total area would be (4 * (20 ft. * 30 ft.) * pitch factor = 2400 sq. ft.
Dividing this by 33.3 would mean you need approximately 72 packs of shingles.
How to Measure a Gambrel Roof for Shingles
A gambrel roof, recognized by its distinctive double-slope on each side, requires careful measurements of each slope for accurate shingle estimation. Measure the dimensions of each plane, adjust for the pitch, then divide by 33.3. This will determine the required number of shingle packs for each slope of your gambrel roof.
If your gambrel roof has two different slopes, one measuring 20 feet by 30 feet and the other measuring 40 feet by 30 feet, with a pitched roof of 6/12, then the total area would be ((20 ft. * 30 ft.) * pitch factor) + ((40 ft. * 30 ft.) * pitch factor) = 1800 sq. ft. + 3600 sq. ft. = 5400 sq. ft.
Dividing this by 33.3 would give you approximately 162 packs of shingles required, with around half for each slope.
How to Measure a Roof for Shingles With Valleys
To measure a roof for shingles with valleys, measure the length and width of each roof plane, including the valleys. For the valleys, measure the length from the ridge top down to where it intersects with another plane. Add up these areas, adjust for the pitch, then divide by 33.3.
Remember to account for extra shingles for the valleys as they typically need more coverage. One extra bundle for every two or three in the field should suffice, depending on the valley design.
For example, if your roof has two planes, each measuring 20 feet by 30 feet, and a valley that measures 10 feet from the ridge top down to where it intersects with the other plane, then the total area would be ((2 * (20 ft. * 30 ft.)) + (10 ft. * 30 ft.) = 600 sq. ft. + 300 sq. ft. = 900 sq. ft.
Adjusting for the pitched roof of 6/12, this would give you approximately 27 packs of shingles required, with a few extra bundles for the valleys.
More on How Many Bundles of Shingles You Need
The number of bundles of shingles you need depends on the size and complexity of your roof.
While the general rule of a bundle of standard three-tab shingles covering approximately 33.3 square feet applies, we need to explore the core concepts that underpin roofing measurements and material calculations.
In the roofing industry, a “square” is a unit of measurement equivalent to 100 square feet. This term is essential to understand as it is widely used in discussing, estimating, and selling roofing materials.
When it comes to shingles, the amount you need is typically talked about in terms of “bundles”. Again, one bundle of shingle generally covers about 1/3 of a roofing square (or 33.3 square feet). This means that for every square of your roof, you’ll need about three bundles of shingles.
However, these numbers can vary depending on the type of shingle you choose.
For example, architectural or dimensional shingles, which are thicker and provide a more textured appearance, often come in smaller bundles that cover less area. This means you might need more bundles of these types of shingles to cover the same area as three-tab shingles.
Overall, the number of shingle bundles required for a roofing project can vary based on several factors:
- Roof size
- Type of shingle used
- Complexity of the roof design
- Accounting for waste
Using Advanced Measurement Techniques
Think you’ve got how to figure shingles for a roof nailed down already? Although you’re aware of the basics already, to determine the number of shingles for your roof, advanced measurement techniques can significantly increase the accuracy of your estimates.
One such method is the use of satellite roofing measurements, which uses high-resolution aerial imagery to capture detailed measurements of a roof. These services provide comprehensive reports that include measurements for each roof plane, pitch, and features like ridges, valleys, and hips.
An example of this is EagleView, which offers detailed roof measurements that are 95% accurate and provide a 3D model of the roof for easier visualization.
If this feels a bit overkill for you, you can use digital measurement tools to calculate the square footage to get the amount of roofing shingles you need. These provide accurate and reliable measurements by overlaying a grid on digital images of your roof. These tools often come with comprehensive software that can automatically calculate the area and the number of shingle bundles needed for each roof section.
A good example of this type of tool is the GAF Roofing Wizard, which uses drone-captured imagery and advanced software to provide precise roof measurements and material needs.
Of course, you can still rely on traditional measurement techniques like those outlined in this guide. However, with the increasing availability and affordability of advanced tools, it’s worth considering these options to ensure the most accurate estimates possible.
If You’re in Wisconsin, Let Us Do the Hard Work for You
If all this calculation and planning feels overwhelming, don’t worry — we’re here to help.
At Prairie Exteriors, our team of experienced professionals can take care of all the complexities of your roofing project.
From planning and measuring to installation and clean-up, as an expert Wisconsin shingle roofer, we handle every detail with precision, ensuring a stress-free process and a finished project that exceeds your expectations.
Why not contact us today for a free, no-obligation quote? Let us put our expertise to work for you.
Final Points on How to Calculate Roof Shingles
As you’ve seen, calculating the number of shingle bundles required for a roofing project is a technical task that takes into account various factors. This includes the total area of the roof, the complexity of its design, and the type of shingles used.
Though this process may seem daunting, it remains an integral part of successful roofing projects. With careful measurement, accurate calculations, and proper waste considerations, you can ensure that your roofing project runs smoothly and efficiently.
Remember to get prepared and put your safety first. And if you need assistance, don’t hesitate to reach out to our professional team — we’re always here to lend a helping hand.
FAQs on On How to Figure Out Shingles for a Roof
What Is the Formula for Measuring a Roof?
The formula for measuring a roof involves taking the horizontal area of each roof plane (length x width) and then multiplying by a pitch factor to get the actual area. You can measure pitch factor using an angle finder (also known as a pitch gauge).
How Many Square Feet Does 1 Bundle of Shingles Cover?
One bundle of shingles typically covers around 33.3 square feet. However, this can vary depending on the size and type of shingles used. To avoid errors and ensure precise calculations for your specific project, it’s always recommended to refer to the detailed specifications provided by the manufacturer.
How Many Square Feet Is a 12×20 Shed Roof?
A 12×20 shed roof is 240 square feet. This calculation is derived from multiplying the length (20 feet) by the width (12 feet). However, if the shed has a pitched roof, you will need to account for this in your calculations by using the pitch factor method.
So for example, if the pitch of your shed roof is 4:12, you would multiply 240 square feet by a pitch factor of 1.06 (obtained using an angle finder), giving you a total of 254.4 square feet.
What Is the Best Tool to Measure a Roof?
In terms of precision, accuracy, and convenience, digital measurement tools such as the GAF Roofing Wizard are considered the best option for measuring roofs. However, traditional methods like using a tape measure and pitch gauge can also yield accurate results with proper technique and attention to detail.
Should I Measure the Roof From the Inside or the Outside?
When it comes to measuring a roof, it is highly recommended to conduct the measurement from the outside. This approach ensures a higher level of accuracy as it takes into consideration any overhangs and eaves that may not be accounted for when measured from the inside.
