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How To Measure Your Roof For Shingles

Why Is It Important To Have An Accurate Roof Measurement

Roof sales is not for everyone. How one video can change your life | Ben Menchaca 2.0

As a homeowner reading this you may be saying so what. If someone makes an error perhaps this is in our favour. The answer is, that often when an error is made on measuring, and a contractor has effectively under-sold the job that corners can be cut, to make up for costs that were not originally factored into a job. Another result is that a job can drag on because of a material shortage is which is discovered when the project is underway.

Where a homeowner should be concerned is during the estimate process.

It is a good idea to ask the estimator to demonstrate how they arrived at the roofs size. Heres why:

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Walk To Your Roof And Measure Physically

Once youre on the roof, its time to check out the map and tape measure so you can get started. Carefully measure the length and width of all sections of the roof, paying special attention to the dimensions in the corresponding sections of the diagram. If your roof has triangular sections, such as a cornice, it is important to measure these as well, as they must also be shingles. Once youre done measuring the entire steep roof, its time to lower the ladder and use the measurements effectively. Finally, increase the total by 15% to account for any waste.

How To Calculate Number Of Roofing Shingles

Fortunately, you dont have to make a haphazard shingle estimate when planning for your roofing project: your roof size and chosen shingle type will guide the purchase process.

Shingles are sold in prepackaged bundles, not individually. Roofing manufacturers take the guesswork out of how many bundles you need per squareits listed in the specifications of each shingle they make. The specs for any given shingle will tell you how many bundles make up a square, how many shingles are in a square, and even the approximate number of nails youll need per square.

Often, three bundles of prepackaged asphalt shingles make one square, as is the case with the Timberline® HDZ Shingles. That said, the number of bundles you need can vary depending on shingle design. For example, five bundles of architectural asphalt shingles with artisan-crafted shapes, such as the Grand Sequoia® Shingle, cover one square. Once you know the number of squares of material your roof needs, check the shingle manufacturer specifications so you get your hands on exactly what you need.

If youre still deciding on the perfect shingle for your roof, play around with the GAF VirtualRemodeler. The free online tool helps you envision how different shingle colors and styles would work with your homes style. Be sure to keep local building codes in mind as you weigh your shingle options..

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How Many Roofing Shingles Do I Need

To estimate how much roofing material you need, such as bundles of architectural shingles or rolls of synthetic roofing underlayment, you need to know the total square footage of your roofs surface.

How to Calculate Total Square Footage of Your Roof

To find your roofs total square footage:

  • Measure the length and width of each plane on the roof then multiply length times width.
  • Add the square footage of each of the planes together.
  • Example #1: Shed Roof with One Roof Plane

    For example, this shed roof has one roof plane.

    Multiply length times width :

    A x B = 40 x 30 = 1200 sq. ft. for the total square footage of the roof.

    Example #2: Gable Roof with Two Roof Planes

    This gable roof has two planes.

    So to derive the total square footage of the roof, you would:

  • Multiply length times width and length times width to get the square footage for each plane.
  • Add the two planes together.
  • For example:

    • Plane 1 : 40 x 30 = 1200 sq. ft.
    • Plane 2 : 40 x 30 = 1200 sq. ft.
    • Plane 1 + Plane 2 = 2400 sq. ft. for the total square footage of the roof.

    How Shingle Quantities Are Measured

    3 Ways to Measure for Roof Shingles

    Roof shingles are sold by both the bundle and by the square. A square of shingles is the quantity needed to cover 100 sq. ft. of roof. Shingles are packaged in paper- or plastic-wrapped bundles designed to be light enough for a person to carry, so heavier shingles require more bundles per square. Three bundles to a square is most common, which applies to most three-tab strip shingles and some lightweight laminated shingles. Heavier three-tabbed shingles and laminated shingles require four, or sometimes five, bundles to cover a square. When shingles come three bundles to the square, there are 29 standard-sized shingles in each bundle.

    Figuring out the roof area is the first step to determine how many bundles youll need to order. There are two ways to size up a new or freshly stripped roof: the measurement method and the sheet-count method. Theres a third method for calculating bundles when youll be laying new shingles over old or if the old roof is still in place.

    Once you have a bundle or square count for the main roof area, youll add additional shingles to account for waste, starter shingles, and extra shingles for hip and ridge caps.

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    What If You Have A Steep Roof

    To measure a steep roof, use one of the following alternate methods:

    Method 1

    Calculate the roof length by measuring the exterior walls plus the overhang for the length of the house parallel to the ridge.

    Next, throw a rope over the ridge and mark it where it meets each eave. This will give the width dimension to use in figuring your area. This should be done on each roof section containing a horizontal ridge.

    Method 2

    Determine the roof area by using a mathematical formula that accounts for the roof length, total span, and roof pitch:

  • Determine your roof pitch by using a pitch gauge or a smartphone app .
  • Measure the length of the roof surface, including overhangs.
  • Measure the span of the roof, including overhangs.
  • Multiply the length x the span. The result will be the plane area. Use the chart below to calculate the total area of the roof.
  • Calculate the total roof area Plane Area x Correction Factor = Roof Area
  • Plan For Extra Valley Material

    Valleys are either woven or cut both methods require about the same number of shingles. On a woven valley, each course of shingles is extended beyond the valley crease and at least 12 in. onto the adjacent roof plane. Youll use 2 ft. of extra shingle material for each pair of woven courses. In the case of cut valleys, the shingles from the first roof plane thats shingled also extend onto the adjacent roof plane at least 12 in. just like woven valleys. Shingles from the next roof plane are cut just up from the valley line, and the cutoff pieces usually arent big enough to use elsewhere on the roof. Order two extra shingles per linear foot of valley to account for the overlaps and cutoffs. On a 16-ft. valley, you would need 32 shingles or roughly one extra bundle.

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    How To Measure My Roof For Shingles

    Measuring a roof for shingles involves many steps. To get a good estimation, youll determine the square footage of the house and multiply it by the roofs pitch. But for accurate measurements, its good to measure each plane on the rooftop.

    Once you get the total area of your roof surface, use the measurement to determine the number of shingles needed for the roof. Unfortunately, some roofs are hard to access, making it tricky for homeowners to take the correct measurements.

    The bottom line for measuring a roof for shingles is to calculate the roofs pitch and the buildings base area. Ground measures are ideal for gabled roofs with two rectangular pitches. But for complex roof structures, youll need a professional roofer to help you.

    Now, lets dive deeper into the steps of how to measure my roof for shingles.

    Roofing: Calculate The Number Of Shingles

    SideBar & Shingle Gauge

      Roofing is a very important part of your house because it protects it from water. Without a watertight room water would be allowed to enter and stream down the walls in your house. It’s essential that the roof is in the very best condition.

      Pitched roofs are commonly weatherproofed by using shingles, and these are arranged so that they overlap one another. It’s important that you have the right number of shingles on your roof, because if you have too few then it won’t be waterproof. You will then need to go back to the store a second time to buy more. Ordering too many roofing shingles will waste money.

      There are a number of calculations that you can use to work out exactly how many shingles you need to correctly cover your roof. These calculations aren’t scary because you don’t need to worry about anything you learned in school.

      Step 1 – Calculating the Square Footage

      The first thing that you will need to do is work out the size of your roof in square feet. This is very easy, as it’s simply a matter of measuring the length and height of the room. Multiply the length and height of the roof together to work out the number of square feet that you need to cover. Remember to work out the total square footage around the whole of your house. For a simple room this will be very easy. However for larger, more complicated shapes you will need to work slowly.

      Step 2 – Working out Number of Squares

      Step 3 – Work out Number of Bundles

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      What Else Impacts The Cost Of Your New Roof

      Now you know how to roughly calculate your roofs square footage and 3 more factors that impact the cost. Remember, the only way to get a 100 percent accurate measurement is to have a local roofing contractor come out to professionally measure your roof.

      Knowing your square footage and the 3 other cost factors lays the groundwork for learning the size of your roof investment. However, there are even more factors that impact the cost of your new roof besides whats listed in this article.

      To understand where your hard-earned money is going when you invest in a new roof, we broke down the 9 factors that affect the cost of your new roof.

      The team at Bill Ragan Roofing has provided high-quality roofing services in the Nashville area since 1990. We give you an experience rare in the roofing industry with our workmanship and customer service.Thats why were proud to offer you a lifetime warranty.

      Hire A Professional Contractor To Measure The Tiles

      As you can see, measuring a tile roof is not as difficult as many would have you believe. However, because it can be difficult to walk on a roof and measure it, it can be dangerous work for inexperienced people. For a simple roof, I generally figure 1 percent as a waste factor. To make life easier and safer, its best to hire a professional contractor to measure your shingles and the best experts.

      Learn To Clean Roof Tiles.

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      How To Calculate Square Footage Of Roof For Shingles

      The most precise way to calculate the square footage of the roof for shingles is by taking exact measurements. This is also one of the riskier methods, as it involves you climbing up on the roof with a tape measure and physically measuring each plane of the roof. If the roof is 8/12 or steeper, do not attempt this method!

      Once on the roof, use a tape measure to take measurements of the length and width of each plane of the roof. Multiply the length and width of the roof to get a measurement of each planes total area. For example, a roof with a single plane that is 50 feet long by 30 feet wide has a total square footage of 1,500 square feet.

      For roofs with two roof planes, such as a gable roof, add up the areas of each plane to get the total square footage of the roof. For example, a roof with two sides that are each 30 by 50 square feet would have the total square footage of 3,000 square feet.

      Do I Need Underlayment Under The Shingles

      3 Ways to Measure for Roof Shingles

      Underlayment is an important part of a roofing project. Some people will try to skip the underlayment to save money, but this can be very costly in the long run. Unless you want to get on the roof every time a few hailstones fall or a branch hits your roof, you probably will have a cracked shingle or two on your roof from time to time.

      If you dont have underlayment, moisture will seep into the crack, seep into your roof decking and eventually cause mold, mildew and rot. It also is a way for insects to get in.

      If moisture gets in because of an undiscovered cracked or broken shingle, youll eventually have a more expensive roofing project to replace the damaged decking that will end up costing more in materials and labor than the underlayment would have cost. Since a roof is something that you want to last a long time, why skimp on it?

      Your roof measurements not only apply to the shingles but also to figure the number of rolls of underlayment youll need. Typically, a 15-pound roll of underlayment will cover about four squares. Again, youll want to allow about fifteen percent more to cover accidental tears or cover odd shapes.

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      How To Measure A Roof For Shingles From The Ground

      Remember when your high school algebra teacher said you needed to know how to calculate slope. He may have been thinking about measuring the square footage of a roof.

      This method allows you to calculate roof slope and determine the roof area while keeping both feet firmly on the ground.

      Begin by measuring the distance from the edge of the eave to the point at which you can barely see the slope of the roof. This works best if you can attach the tape measure to the eve, then walk to the appropriate place and take the measurement at eye level.

      This measurement is the horizontal run of the roof. Now, stand under the gutter of the roof you are measuring the slope for and measure the distance from your eye to the roof overhang. This is the roof rise.

      Divide the roof rise by the horizontal run to get your roof pitch. For example, if the rise is 60 inches and the run is 120 inches, youll have a roof pitch of 6/12.

      As in the method described above, measure the length of the roof from the edge of one eave to the other and the width from one eave to the other. For example, a roof that measures 60 feet by 40 feet would be 2,400 square feet.

      Next, use the table below to determine the slope factor. In our example, the 6/12 roof would have a slope factor of 1.118. In our above example, you would multiply 2,400 square feet times the slope factor to get the total square footage of 2,683 square feet.

      How To Measure Your Total Roof Area

      Length x width = square footage

      In order to determine the amount of shingles you need for your roof, youll need to know the square footage of your roofs surface. Measurements for the area of the roof will depend on what roof type you may have, whether its a gable roof with fewer planes or a hip roof with more.

      To find the square footage of your roof, measure the roof length and roof width of each plane, including overhangs, and multiply them together. Then, add up the square footage of each plane. This will give you the total square footage.

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      Calculating How Many Shingles Youll Need

    • 1Convert the area into roofing squares, the measurement used for materials. In roofing terms, a square is 100 square feet . Therefore, divide your total area by 100 to get the number of squares.XResearch source
    • So, for instance, if your total is 2,381 square feet, thats approximately 23.8 squares or 24 squares, rounded up.
    • You can also use an app or a roofing calculator to decide how many shingles youll need.
    • If youre in a country other than the U.S., check the size of roofing bundles in your area before making this calculation, as they can vary from country to country.
    • 2Determine the number of shingle bundles youll need by multiplying by 3. Shingles typically come in a bundle thats large enough to cover 1/3 of a square. To figure out how many bundles youll need, multiply the number of squares by 3.XResearch source
    • So if you have 24 squares, multiply that by 3 to get 72 bundles.
    • 3Figure out the amount of roofing felt youll need by dividing by 2 or 4. Felt is what goes under the shingles. If youre buying 15-pound felt, 1 roll will be enough for 4 squares. If youre buying 30-pound felt, 1 roll will be enough for 2 squares. Divide your squares by one of these numbers to get the number of rolls youll need, depending on the thickness of felt you want.XResearch source
    • If youre trying to cover 24 squares, divide by 4 for a 15-pound roll to get 6 rolls.
    • If youre trying to cover 24 squares with a 30-pound roll, divide by 2 to get 12 rolls.
    • How Do You Calculate Roofing

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      Roof Measurements Measure each plane of your roof by length and width. Divide this number by 100 to determine how many squares you have in your roof area. Add 10 percent for any overage that might be needed when installing the shingles. Divide the total number by 3, and you will know how many bundles you need to purchase for your roofing project.

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