aerial roof measurement

Roofing Measurements

Getting accurate roof measurements can be difficult but with this roofing calculator, you’ll be well prepared to take measurements of any roof. Whether you’re a contractor looking to train a new employee or a homeowner looking to do some renovations, you’ll find this guide helpful for any roofing project. Use the step-by-step guide below to accurately measure your roof and estimate roofing costs.

How to measure your roof area from the ground

A more accurate way to calculate the area of the roof than using Google Earth is to get outside to estimate the roof pitch and the base area of the property. Using these two figures, we can get a good idea of the shingle roof’s square footage and estimate your asphalt shingles’ needs and costs. This DIY technique can be helpful, especially if you are not comfortable getting on your roof, or if you have limited access to it.

Ground measures only work well for a gabled roof, since there are usually just two main rectangular pitches to calculate area for. For more complex roof shapes, like hip roofs, you’ll need to work with a roofer or measure from on top of the roof itself to calculate its total area.

HIRING A PROFESSIONAL SERVICE

There are a number of local services in every community that will measure your roof and give you an accurate coverage area. This is the easiest solution to finding out your roof’s dimensions. Often, roofing professionals will offer this service as a part of their installation costs, or even sometimes for free.

ROOF SAFETY & AWARENESS

If you’re thinking about measuring your roof yourself, please take caution as falling from roofs is a regular injury. Be sure to wear proper safety equipment, and if possible, have someone else there to assist you. Take extra precaution as you move up or down from the roof itself.

Estimate The Amount of Shingles

roofer

To estimate how many shingles you’ll need, first estimate the total square footage of your roof’s surface. To do this, measure the length and width of each plane on the roof, including dormers. Then, multiply length x width to get the square footage of each plane. Finally, calculate your roof’s total square footage by simply adding the square footage of each of the planes together.

For example, this shed roof has one roof plane. Simply measure length (A) x width (B): A x B = 120′ x 100′ = 12,000 sq. ft. for the total square footage of the roof.

This gable roof has two planes. So, multiply length (A) x width (B) to get the square footage for each plane. Then, add the two planes together to derive the total square footage of the roof:

  • Plane 1: 120′ x 100′ = 12,000 sq. ft.
  • Plane 2: 120′ x 100′ = 12,000 sq. ft.
  • Plane 1 + Plane 2 = 24,000 sq. ft. for the total square footage of the roof.

Roof surfaces are measured in “squares.” A square is an area of roof which measures 100 square feet. To determine the number of squares on the gable roof above, simply divide its total of 24,000 square feet by 100. The result is 240, and this means you would need 240 squares of shingles to cover that roof. The most common type of shingle, called a three-tab or strip shingle, is generally packaged three bundles per square.

For a new roof, you will also need the same amount of underlayment. So, in the gable roof example above, you would need 240 squares of underlayment. Underlayment usually comes in rolls of 4 squares each. So, covering 240 squares would require 60 rolls of underlayment. No underlayment is needed if you are applying shingles directly over an existing asphalt roof.

Be sure to add 10% to all of your material totals for trim allowance.

Finally, if you have any questions about your estimate, ask a roofing contractor in your area. Most will be happy to give you a free estimate. For a listing of roofing contractors in your area, use our Find a Roofing Professional locator tool.

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Roofing Calculator – How to Measure a Roof

How to Calculate Total Square Footage of Your Roof. To find your roof’s total square footage: Measure the length and width of each plane on the roof (including dormers) then multiply length times width. Add the square footage of each of the planes together.

How do you calculate the roof area?

  1. Begin with calculating the area of your house in a plane parallel to the ground. If your house is rectangular, all you need to do is multiply the length and width of the building. If the shape of your house is more complex, simply enter the total area (after measuring the exterior dimensions) into the appropriate box.

  2. Determine the roof pitch of your house. Roof pitch is the slope created by the rafters. If you don’t know how to calculate it, head to our roof pitch calculator. You can input it either in degrees, as a percentage or as a ratio of x:12.

  3. Once you know these values, you will be able to calculate the roof area. Begin by converting the roof pitch to an angle expressed in degrees, using the following formulas:

    pitch(%) = x / 12 * 100%

    pitch(deg) = arctan[pitch(%)]

  4. Then, use the following equation to find the total area of the roof:

    roof area = base area / cos[pitch(deg)]

Tips on measuring for roofing

Measuring your roof’s dimensions is one of the most important aspects of any roofing job, so make sure your tools are up to par. An accurate ruler, tape measure, and a sturdy ladder are all required.

The problem is that not everyone is comfortable with climbing a ladder to do this. What’s more, there is no guarantee that the measurements will be correct. That error can cost you more money, time, and effort.

That’s why it’s best just to hire or consult a professional roofing contractor. They will have the tools, knowledge, and experience to help you accurately measure your roof and figure out how much materials you need with minimal waste.

How to Measure a Roof for Shingles

Don’t worry too much if you don’t know how to measure a roof for shingles. Your roofer will measure the surface of your roof to determine the total square footage, which will dictate how many shingles must be purchased to fully cover the roof’s planes.

But if you’re curious how the measuring process works, think back to your geometry classes in school. To calculate a rough estimate, follow these steps:

  1. First, you must measure the length and width of each plane of the roof, including dormers. If the planes aren’t rectangles, this may be complicated.
  2. Next, to calculate the square footage of each rectangular plane, multiply the length by the width. For example, if a plane is 130 feet long and 100 feet wide, it’s 13,000 square feet.
  3. Finally, add together the square footage of each plane to calculate the total square footage of the roof. So if there are two planes that both measure 13,000 square feet, the total square footage of the roof is 26,000 square feet.
Aerial measurement

Roofing Resolutions for the New Year

Since we already wrapped up 2020, we’ve all geared up to rang in the New Year. It’s an excellent time to look past the holidays and focus in on the health of your roof this year. A lot of us like to create lists containing our New Year’s Resolutions to achieve on a personal level. Some of the most common resolutions include losing weight, giving up smoking, saving money and vacationing more. But have you considered focusing your resolution efforts on your home or business and making some money-saving roof resolutions?

Clean your commercial roof: OMG! We have literally inspected thousands of commercial flat roofs that were full of debris. Beside the obvious, a clean flat roof looks better than a dirty flat roof; a clean flat roof performs better than a dirty one. If your flat roof has leaves, foliage and other roof debris it not only inhibits drainage but it foster organic growth. Roof debris can clog in-roof drains and scuppers. This roof debris begins to decompose on your roof’s surface, which can cause your roofing membrane to deteriorate prematurely… ROT!

If you have a single ply roof system like TPO, an annual roof cleaning of the roof’s surface will bring back it to its bright white appearance and its reflectivity, which will improve the energy efficiency of the TPO roof system.

Resolve to Schedule Annual Maintenance

One of the best (and easiest!) things you can do for your roof this year is schedule an annual inspection and maintenance visit with a professional. While your roof is designed to last for decades, the only way to get the most out of it is to keep it well-maintained. This includes making repairs and replacing worn-out or damaged parts.

While the average homeowner can do a lot to help maintain their roof, a professional roofer has the knowledge and experience to catch the issues you may miss. Working with a professional can bring you peace of mind knowing your roof is receiving the best possible care.

The benefits of professional roof maintenance include:

  • Fewer repair problems
  • Improved energy efficiency
  • Extended lifespan of your existing roof
  • Reduced maintenance costs overall

Educate Yourself

Even if you have been in roofing for your entire career, believe us, there are things that you don’t know. That may sound harsh, so let us follow up with a positive spin: there’s so much left to learn! Take some time this year to explore educational opportunities for yourself and others at your company. You can go low-effort and join an industry Facebook group, or take a bigger step and join your local Builders Exchange. Either way, you’ll be exposed to new thoughts, new ideas, and new products that can benefit your business.

Mind The Landscaping: Roofing is intended to protect your home from the weather, not repel trees. Keep branches trimmed away from your roof each spring and fall, and prevent damage. Similarly, make the effort to clean your gutters and downspouts of leaves and other debris every fall to ensure proper drainage.

Know Your Roof: Every roof eventually needs to be replaced. Do you know your roof’s expected lifespan? Stay in front of repairs – and the damages to your home that can be caused by a failing roof – by knowing when it’s time to start planning for a new roof.

Invest in Roof Repairs Early

Finally, it is also a great resolution to invest in repairs for a roof as early as possible. Some of the most common signs of roof damage include damaged flashing and missing shingles. If people put off their roof repairs, this can lead to an even larger repair bill down the road. Catch these problems as early as possible. This will prevent the damage from building up down the road. Even though these issues might seem minor at the time, this damage can also lead to pest infestations and water leaks.