On the surface, a roofing square is just a simple unit of measurement. One square equals a 10 by 10 foot area, or 100 square feet. That’s simple enough.
But a roof square is also vital for running a successful roofing business. Squares help you forecast everything from materials to labor needed for a job. Also, they’re critical for generating accurate estimates quickly.
If you’re not sure how to measure with roofing squares, read on. This guide offers step-by-step instructions and tips for what to do when manually measuring with squares isn’t the best way forward.
The Importance of Accurate Roof Measurement
With close to 100,000 roofing companies in the US, there’s no question that this industry is competitive. That’s why creating fast, accurate quotes is so important. And an accurate quote starts with accurate measurements.
Roofing squares help here because they tell you exactly how much material you need. They are the standardized measurements for the entire industry. They’re also the unit manufacturers use to sell roofing materials.
Using roof squares to generate accurate measurements also translates to:
- Less waste: When you know what to buy, you can avoid overspending on projects or over-quoting clients.
- Faster jobs: With the right amount of materials, your team can lay the roofing quickly.
- Fewer delays: Mistakes in measurements can cause project delays. But when your dimensions are flawless, you don’t have to worry about ordering more materials or explaining hiccups to your clients.
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9 Steps for Measuring with Roofing Squares
Roofing squares make it easier to measure a large space—like a roof—quickly. Instead of measuring with small units like feet or yards, you’re looking at the number of 10-by-10-foot blocks.
For example, a roof with 2,400 square feet is 24 roofing squares.
That’s because 2,400 square feet divided by 100 square feet (the equivalent of one roof square) is 24.
Keep in mind: a roof square isn’t exactly 100 square feet. It’s actually a measurement for the amount of roofing material for 100 square feet. It’s not necessarily the actual physical space.
So, while a roof square is close to 100 square feet, the roofing square you use to create a quote and order materials will usually be slightly more because of one or all of the following:
- The roof’s pitch (slope)
- Headlap (the overlap of shingles or tiles)
- Architectural factors, such as dormers and valleys
Knowing the background behind this handy unit of measurement, let’s look at the steps for measuring with roofing squares.
1. Gather Necessary Tools
To measure a roof, you’ll need the following:
- Measuring tape
- Ladder
- A two-foot level
- Pen and paper to record the dimensions
2. Measure the Roof Planes
Take measurements for each plane. A roof plane is a flat surface at an angle that has four sides.
Measure the length and width of each in feet.
3. Find the Square Footage of Each Plane
Once you have the length and width, you can calculate the surface area of each plane in square feet.
Multiply the length times the width to find the area. For example, a roof plane that’s 12 feet high and 20 feet wide has a surface area of 240 square feet.
4. Calculate the Total Area of the Roof
Add up the square feet of every roof plane to determine the total square footage.
Using this total, you can find a rough estimate of your roofing squares. Dividing the total by 100 tells you how many squares of material you need.
Here’s an example:
A roof has four planes. The length times width for the first plane is 240 square feet. For the second, it’s 1,200 square feet. The third is 1,400 square feet. And the fourth is 160 square feet.
Add all those measurements, and the roof has 3,000 square feet.
Next, divide 3,000 square feet by 100 square feet to find the number of roofing squares. So, for this roof, you’d need material for 30 roofing squares.
This number will change based on the slope, your roofing materials, and the roof’s features, so consider 30 roof squares as your ballpark figure.
5. Determine the Roof’s Slope
Pitch (slope) impacts how much roofing material is necessary to cover a roof’s surface. The steeper the roof, the more roofing material that’s required to cover the surface.
How do roofers determine how much more roofing material is needed based on the pitch?
With a roofing pitch multiplier. But to calculate that, you must find out the roof’s slope first.
Here’s how to do just that:
- Take your two-foot level and go to the roof’s peak.
- Extend the level horizontally outward at the peak.
- Take out your measuring tape and measure the distance from the 12-inch mark on the level to the roof.
- This distance is the drop, also known as the rise in the slope.
Maybe you remember from high school math that slope equals rise over run.
In this case, rise is the drop or vertical distance. The run is 12 inches. That’s the horizontal distance you used from the roof’s peak.
Let’s say the drop is five inches. That means the slope is 5 ⁄ 12.
Once you have the slope, you can calculate the roof pitch multiplier.
6. Calculate the Pitch Multiplier
The formula for the roof pitch multiplier is based on the Pythagorean theorem: a2 + b2 = c2.
a = the rise
b = the run
c = the hypotenuse
The hypotenuse is the longest side of the triangle. When measuring the slope of the roof, the hypotenuse is the rafter, which you can calculate using the Pythagorean theorem. Once you do that, you can find the roof pitch multiplier, which is c ⁄ b.
Here’s an example of how this calculation works:
In our example, we measured 5 ⁄ 12 for the slope. So, a = 5, and b = 12.
Using the Pythagorean theorem, a2 + b2 = c2, we can solve for c.
5 squared + 12 squared = c2
25 + 144 = c2
c2 = 169
The square root of 169 is 13. So, c = 13.
Next, divide c by b to find the multiplier.
13 ⁄ 12 = 1.08
1.08 is the roof pitch multiplier when your slope is 5 ⁄ 12.
Calculating the pitch multiplier helps you understand the math behind this figure. You can also use this list of each slope and the corresponding multiplier as a shortcut:
- 1 ⁄ 12 — 1.0035
- 2 ⁄ 12 — 1.01
- 3 ⁄ 12 — 1.0308
- 4 ⁄ 12 — 1.05
- 5 ⁄ 12 — 1.08
- 6 ⁄ 12 — 1.12
- 7 ⁄ 12 — 1.16
- 8 ⁄ 12 — 1.20
- 9 ⁄ 12 — 1.25
- 10 ⁄ 12 — 1.30
- 11 ⁄ 12 — 1.36
- 12 ⁄ 12 — 1.4142
7. Multiply the Roofing Squares by the Pitch Multiplier
Once you have the multiplier, you can find a more accurate estimate of your roofing squares.
Simply multiply the multiplier by the roofing squares.
In our example above, we measured 30 roofing squares. With a slope of 5 ⁄ 12, multiply by the pitch multiplier (1.08).
30 x 1.08 = 32.4 roofing squares
8. Consider the Headlap Based on the Roofing Material
Headlap is the amount of a lower part of a tile or slate that overlaps with the tiles or slates below. This overlap increases the actual amount of roofing material you need to cover the surface.
The standard minimum headlap is three inches. However, it varies with different roofing materials. You can check the headlap for the material you’re using for a job by checking the manufacturer’s recommendations.
You don’t need to calculate the headlap when measuring your roof. But it is important to understand that when you buy one roofing square, you’re buying enough material to cover 100 square feet of the roof’s surface. And because of the headlap, the actual material will be more than 100 square feet.
9. Factor in Complex Features with Multipliers
If you’re working with a roof with dormers, hills, valleys, and other complex features, you’ll need more roofing materials. With extra material—the roofing waste—you can cut the shingles or tiles to fit the shape of the roof.
For example, for a roof with two gables, you might use a multiplier like 1.3. You can estimate the complexity multiplier based on your experience. Another option is to get professional help for measuring with roofing squares or use software.
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When to Seek Professional Help
The more complex the roof, the more factors that go into determining how many roofing squares of material you need. Being as accurate as possible is important so you don’t buy too little or too much material. Also, it will help you create a more accurate estimate.
So how do you know when to get outside help?
Here are three scenarios that warrant either using software or a professional estimator:
- You have a new roofing company. Until you have more experience with roofing estimates, hiring a professional or using roofing software can help ensure you produce accurate measurements.
- The roof is complex. When a job involves multiple levels and more than one extra architectural feature, don’t try to measure it yourself. The time and energy involved to do it manually isn’t worth it.
- You are under time constraints and want a faster option. Roofing software can generate accurate roof estimates in under 30 minutes.
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Top Takeaways on Utilizing Roofing Squares
- Make sure you have the right materials. You need measuring tape and a level to find the dimensions for most roofs. Consider using a digital tape measure for faster measurements.
- Establish your multipliers. A big part of roofing square measurements is the multiplier. Keep the list of pitch multipliers handy so you don’t have to calculate it each time. If you work with complex roofs, use software to make sure you’re getting accurate measurements.
- Familiarize yourself with roofing material prices. Find out the typical prices for the various roofing materials in your area. Knowing how much asphalt, metal shingles, clay tiles, and other materials cost will help you discuss prices with your clients.
