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How To Calculate Square Footage Of A House Roof

How To Calculate A Roofing Square

How to Measure the Square Footage of a Roof

Before beginning, make sure you can safely access your roofif you cant, contact a roofing professional for help.

Grab your measuring tape, level, pen and paper, roof safety equipment, and your ladder. With these in hand, you can measure your roof in five simple steps.

  • Determine the number of planes. Your roof is made up of planes. If you have a flat roof, it has one plane. If you have a simple gable roof, it has two planes. The more architectural details your roof has, the more planes you will have to measure.
  • Measure each plane. Find the length and width of each plane. Then, multiply those two numbers together to find the square footage of that plane. For example, a 35 ft. X 36 ft. plane = 1260 sq. ft.
  • Find the total of all the planes. Add the square footage for each roof plane into one total. 1,260 sq. ft. + 1,260 sq. ft. = 2,520 sq. ft.
  • Divide to find the squares. To find how many squares are on your roof, divide the total square footage of all your planes by 100. In our example, the total was 25.2 squares 2,520 sq. ft. divided by 100.
  • Remember the roof slope. Roof slope indicates how steep your roof is and may increase the number of squares of materials you need. Roof slope is calculated by determining how many inches a roof rises vertically for every 12 inches it extends horizontally. For example, if that vertical rise is 4 inches, the slope is 4:12.
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    How To Figure Out The Square Footage Of A Roof

    Repairing or replacing your roof can be expensive, especially if you dont know how to calculate its square footage. A wrong estimate can cost you thousands of dollars and might even delay your roof repair, leaving your home exposed to the elements. The good news is you can easily estimate the square footage of your roof with a few tools and basic geometry.

    General Concept To Calculate Roof Area

    The area of any of the surfaces is calculated by multiplying length and width. Measurements of base length and base width are needed to evaluate the square footage of the roof.

    Base length is the distance from one roof corner to another following the long side of the house, whereas base width is the distance from one roof corner to another following the short side of the house.

    The calculation is done at the point for a flat roof. However, many roofs have angles that mean one last measurement is needed to calculate the roof area, i.e., roof pitch.

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    How To Measure A Roof From The Ground

    Measure out from the face of the wall below the fascia or rafter tails to a point that aligns with the outer edge of the roof. Multiply this measurement by the length of the roof from end to end, and add this to the first result. Double the result to determine the total area of the roof at both sides.

    How do you measure the pitch of a roof from the outside?

    measureroof pitchmeasuremeasureroof

    Is the square footage of a house the same as the roof?

    Square Footage of Your Roof:

    So a trick to estimate your roof size is to multiply the square footage of your house by 1.5 .

    Draw Each Shape Individually Calculate Each Area And The Total Square Footage Of Your Roof

    Roofing Material Calculator

    Now we have eight shapes to find the area of six triangles and two rectangles. Instead of breaking out the old textbooks to calculate triangle areas, we like to use a triangle calculator. It makes figuring out the area of triangles a lot simpler.

    In the example above, we have two triangles with sides of 30, 20, and 20 feet. Pop those figures in the three-sides calculator and youll get an area of 198. Since we have two of those triangles, multiply by 2 for a running total of 396 square feet.

    We have four remaining triangles, all with dimensions of 15, 20, and 25 feet. That same calculator reveals a result of 150 square feet. Since there are four of those triangles, multiply by 4 to get 600 square feet.

    Lastly, we have two rectangles of 15 by 30 feet. This one is easy, just width times height for a total of 450 square feet for each one. Multiply by 2 and their total square footage is 900.

    Adding all the areas up yields a total of 1896 square feet . Since roofing material comes in 100 square foot squares, youll need at least 19 of them for your roofing project. Itd be wise to get at least 20 to account for mistakes and waste.

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    Gable Roof Area Calculation

    You will first need to evaluate the roof length as it is the length of the roofs ridge from end to end. Then you will need to assess the slope height of the roof.

    It is the length from eaves to the ridge, not the distance between your roof deck and apex. If you do not know about these measurements, you can find them on the building plans when you purchase the property.

    To calculate the roof area, multiply the length of the roof by the slope height of the roof and multiply it by 2. It will give you the total roof area, excluding chimneys or other sections not covered by tiles.

    Area of roof = roof length * slope height of the roof

    For instance, the slope height of the roof is 7 meters, with 9 meters roof length having a pitch angle of 45 degrees. Using the above calculation * 2 = 126 square meters. Add about 10% extra for the damages if any occurs.

    How Do You Calculate Square Footage For A Roof

    Related Articles

    When a roof needs to be replaced, one of the first steps you may perform is figuring out the roof area. Both the roof area and pitch contribute to the cost of a roofing job. Calculate square footage for a roof by measuring and by performing some basic math equations. With the area measurement, you can learn the approximate cost of a new roof. Use this information if you are purchasing a home that needs a new roof or if your current home needs one.

  • Measure the ground dimensions of the house using a tape measure, and write down these dimensions. Multiply the length by the width to arrive at the ground area of the house. If the house has an irregular shape, measure each part separately, figure the separate areas and add them together.

  • Convert the area to roofing squares. Because each 100 square feet of roof is one roofing square, divide the total area from Step 1 by 100. The answer is the number of roofing squares for the roof.

  • Estimate the pitch of the roof. Roofs have one of three pitches: low, medium or high. A low pitch rises 3 inches every 12 inches of base horizontal length. A medium pitch rises 6 to 9 inches every 12 inches of base horizontal length. A high pitch roof rises more than 9 inches for every 12 inches of base horizontal length. Estimate the roof pitch by sight or calculate it with a level in the next step.

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    Recommendation Of How To Calculate Square Footage Of A Roof

    The construction process likes precision. To correctly build and lay a roof firstly it is necessary to understand all nuances of how to calculate square footage of a roof.

    Very often people decide to make a roof and a house itself on their own. In this case they should definitely know how to calculate square footage of a roof. In the space calculation you must be especially careful, since with the wrong approach you risk not only to get an ugly structure appearance, but also spend money for the purchase of excess materials.

    Keep The Slope And Complexity Of Your Roof In Mind

    How to measure a roof and calculate square feet. | 01/2020

    You have to keep in mind the makeup of your roof when doing the calculation for the square footage. The steepness and complexity will change the number you multiply the footprint by.

    For example:

    For an easy up and over, walkable gable roof, youll multiply the footprint of the roof by 1.3 to get the square footage of your roof.

    For a hip roof with a low slope, you’ll multiply the footprint of the roof by 1.4 to get the square footage of your roof.

    For a steep and complex roof, you’ll multiply the footprint of the roof by 1.6 to get the square footage of your roof.

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    Roofing Square: How Its Calculated And More

    Can there be anything more exciting than building your own property? There are so many things that go into building your establishment, be it commercial or residential.

    You have to think of the location, the layout, the size and measurement of the rooms, and so much more. The type of roofing you will opt for is another important aspect to take into account. While all of this sounds exciting, it can be equally tedious.

    When you leave it to a contractor to choose a roof type for your home, or to replace the roof in your home, you may come across them using the following term, roofing square to describe the size of your roof.

    No matter how good you are at math, you may have found that your calculations in terms of how much roofing supplies are required to put up the roofing system in your home are entirely different from what the roofing contractors you hired calculate them.

    When it comes to building roofs, there are two important aspects to keep in mind:

    • Roof measurements
    • Roofing materials estimation

    The one word that commonly gets thrown around in the world of roofing construction is roofing squares. Lets look more into what a roofing square is and why and how it matters in evaluating the shingles or roofing materials you will require in the following sections.

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    Calculate The Square Footage Of Your Roof

    Now that you thought about the slope and complexity of your roof, youre ready to learn how to calculate the square footage of your roof.

    To get a rough estimate for your roofs square footage, youll use this equation:

    For example, if you have an easy up and over, walkable gable roof and a house that measures 56 feet lengthwise and 28 feet widthwise, your calculation will look like this:

    1,568′ =

    x 1.3

    2,038 = square feet of roof area

    Using this equation wont be 100% accurate, but knowing your roofs square footage is a great jumping-off point to learn how much youll have to invest in your replacement.

    Also Check: How To Repair Roof Trusses

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    Below, there is a simple triangle, and the math used to work out how to make a proper measurement. Once you work through the basic triangle, we will review a typical roof, and how to apply some simple math to calculate how much material you will need for a roof used in our hypothetical example.

    1 roof square = 100 square feet The length times the height of a triangle is twice its area . So if you divide your answer of a product of length times height by two, you will get the area of a triangle. /2 = Area

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    In Figure above: l=30 feet h=12 feet /2 = 180 square feet

    Now that the basic concept has been covered, lets take a look at a more complex roofing system. In this overhead view you see both a hip-end section, and gable ends. With a more complex roof such is this one, it is highly recommended that you make a basic sketch. By doing so, it will be easier to mark your measurements, and calculate the necessary materials for the project. For this example we will break this roof up into sections labeled A through E.

    In the figure B. above, a sketched portion is a basic triangle. As we did in the first example, measure the length of the eaves, and the vertical line from the eaves half way point to the peak. Multiply these numbers, and then divide the answer by two./2 = 270 square feet

    S1 = /2 = 135 square feetS2 = 50 × 15 = 750 square feetS3 = /2 = 135 square feet

    How Many Bundles Of Shingles Do I Need Calculator

    How to calculate square footage of a roof with different shapes?

    The most accurate way to calculate how many bundles of shingles youll need is to get up on the roof and measure each roof plane. If all the roof planes are rectangles, you simply need to multiply the length times the width of each plane to get the square footage then you will add up the square footage of each plane.

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    Measuring Or Calculating Gable And Hip Lengths

    The slope factor is also used to determine gable lengths when the run length is known. For example, in Figure 4 the bottom left gable measures 16 across from eave to eave and therefore has a run of 8. When this is multiplied by 1.202 the gable distance is 98 . Note that this run can also be multiplied by the hip/valley factor of 1.563 to get a valley length of 126.

    Record all your calculations on your drawing as seen in Figure 5 below.

    Figure 5. Completed Roof Plan Drawing

    Pro Tip: A Note About Waste Factor

    Once you have figured out your roof area, you will need to also calculate how much room you need to allow for waste. For metal roofing products on a medium complex roof a waste factor of 15% is advisable. In other words for the 2468 ft2 roof in our example you should multiply by 1.15 giving you 2838.2 ft2 roofing material needed.

    Important Note: Most metal roofing products are packaged and sold by the square so for our example roof the number of squares or boxes to purchase is 29.

    Find The Area Of The Footprint Of The Roof

    To calculate a roofs dimensions, you need to measure the roof as if it were flat, then account for roof pitch, calculate square footage, and finally determine how many squares of material are required for the roof.

    The calculator above can handle all of this, simply enter the length, width, and pitch, and it will determine the size of the roof in squares.

    Start by measuring the roofs length and width in feet as youre standing on the ground. Remember that the length and width need to be found for the roof, not the house, so take into account that the roof overhangs the building.

    Then determine the area of the roof as if it were flat. Multiply the length by the width in feet to get the area measurement.

    Also Check: Cutting Roof Trusses

    Ask Alpha Roofing For An Estimate

    As you can see, a roofing calculator can give you an idea of the materials for a roofing project however, its complicated. Roofing contractors have different methods that can be used, so you really should ask a professional for help.

    Alpha Roofing is an award-winning contractor serving Austin, Texas and surrounding areas. We offer a full range of rooftop services, including asphalt shingle installation and repairs, metal roofing systems and chimney repair. We also installsiding and skylights. Our crews are highly trained and work only for us. We are committed to providing quality work and outstanding customer service at affordable rates. Call 777-1086 or complete the online form to request a free quote.

    We service the areas of Buda, Kyle, Killeen, Cedar Park, Leander, Belton, Hutto, Tyler, Lakeway, Lago Vista, and Taylor, TX!

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    Home Diy : Measuring Your Own Roof To Get An Accurate Quote

    Roof Area video

    Theres perhaps nothing a Dallas / Ft. Worth contractor dreads more than a potential customer calling up and asking how much to build a garage or what would it cost to remodel my basement? Theres simply too many details that go into any contracting project for it to be fair to the customer or the builder to give a rough quote over the phone.

    Along those same lines of common projects with almost unlimited variables is putting a new roof on your house. Factors such as how many layers of shingles underneath need to be torn off, the condition of the plywood sheeting, and the type of new shingles being installed all change the estimate of a new roof. For somebody with a roof leaking into the house, time is of the essence and you might not be able to wait for a contractor to get to your home, measure the roof, and draw up the bid. One way you can narrow down prospective roofing companies is by measuring your own roof with these steps and asking for a quote based on your exact square footage and design.

    Know Your Roof Type
    Get a Friend, Get On the Roof, and Measure Your Roof
    Make a Blueprint and Calculate Roofing Square

    Once youve created a blueprint and calculated the total square footage, you need to convert that into roofing square. A roofing square is 100 square feet this means that if the total area of your roof after adding together all the plains was 2000 square feet, youd divide that by 100 to need 20 square of shingles.

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    Estimating Materials Based On Actual Measurements

    Measuring each roof plane requires you to actually go onto your roof. If your roof has a number of planes and numerous hips, ridges and valleys, this is the most accurate way to calculate the materials needed. Take a metal tape measure and a pen and paper. Measure each planes length and width. Record your measurements. Once you are safely on the ground, use your measurements to determine the square footage.

    For rectangular areas, multiply the length by the width. For example, if a plane measures 30 feet by 100 feet, this would be 3,000 square feet. For triangular areas, you may need to dust off your geometry book. If the area forms a right triangle, you can make use of the Pythagorean theorem. Otherwise, you might want to look up how to calculate the semiperimeter and then use Herons formula to find the area. Be sure to add extra for valleys, hips and ridges.

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