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How To Figure Out Square Footage On A Roof

Tips For Getting Started

How to Measure the Square Footage of a Roof

Tip 1: Measuring to the nearest inch along eaves and across gables can be done from the ground just dont forget the overhang.

Tip 2: If you know the dimensions of your previous asphalt roofing job, you can use this info to cheat a little. Typical 3 Tab asphalt shingles have tabs that are 1 foot wide with a vertical exposure of 5 inches. Make sure to physically verify these dimensions by measuring 4 or 5 courses. Counting the shingles can give you eave to ridge dimensions from the ground.

Tip 3: 100 Square Feet = 1 Square in Roofing Terms

How To Measure A Roof

This article was co-authored by David Bitan. David Bitan is a roofing professional, licensed contractor, and the owner and founder of Bumble Roofing based in Southern California. With over 12 years of construction industry experience, David specializes in restoring, repairing, and maintaining residential, commercial, and industrial roofs. With over 60 years of combined experience, Bumble Roofing provides easy, friendly services to structures including residential, commercial, industrial, multi-family, and government buildings along with hospitals, hotels, and churches.There are 13 references cited in this article, which can be found at the bottom of the page. This article has been viewed 342,863 times.

Measuring your roof is the first step in a successful re-roofing project. You can actually get an estimate of your roof’s measurements from the ground if you’d rather not climb a ladder and get up on the roof yourself. Otherwise, you can climb up onto your roof to take more accurate measurements. Either way, we’ve got you covered! This article will walk you through each process step-by-step.

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 .

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How Many Bundles Of Shingles Per Square

A package of roofing shingles is called a bundle. Laminate or architectural shingles, one of the most common types of roofing shingles, are generally packaged in three bundles per square.

So in the 2400 square foot gable roof example, you would need 72 bundles of shingles .

Here are a couple more examples:

Convert All Of Your Measurements To Feet

Roofing Calculator
  • If you measured in feet skip to “Calculate the Area as Square Footage”
  • If you measured in feet & inches, divide inches by 12 and add that to your feet measure to get total feet
  • If you measured in another unit of measure, do the following toconvert to feet – inches: divide by 12 and that is your measurement in feet – yards: multiply by 3 and that is your measurement in feet – centimeters: multiply by 0.03281 to convert to feet – meters: multiply by 3.281 to convert to feet

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How Do You Calculate Square Footage For A Roof

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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.

  • Things You Will Need

    Figuring Out The Square Footage Of Your Roof

    While it may seem difficult at first, you can divide your roof into 10 x 10 roofing squares, a standard unit of measurement used by roofers.

    But first, some terminology you’ll need to know:

    • Ridge – Where two sloped roof areas meet
    • Valley – Where two sloped roof areas meet , often with a metal channel running along the fold
    • Hip Roof – Type of roof where all sides slope downwards to the walls
    • Hip End – The triangle shaped end of a hip roof

    Related: Roofing 101: What Are the Different Parts of the Roof Called?

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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
  • Figure Out Your Homes Footprint

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

    If you use the square footage of your home, youll only get a vague idea of what the square footage of your roof is. Thats why you have to figure out your homes footprint.

    A person of average height will have a stride somewhere between 2 to 2.5 feet. To figure out your homes footprint, you can step off the dimensions of your roof by counting the steps you take to get the length of your home. You will then step off the width of your home.

    After stepping off the length and width of your home, youll multiply the two numbers to get your homes footprint.

    Length x width = your home’s footprint

    Your calculations are going to be off, but measuring this way can give you a basic idea of your homes footprint. Keep in mind, square footage of a house does not equal the square footage of a roof.

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

    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.

    Straight To The Answer

  • Divide your roof pitch by 12. Roof pitch is given as the number of inches in height change over the distance of one foot. Dividing by 12 gives the ratio of inches in rise per distance. For example, a standard roof pitch is likely to be about 4. So for a pitch angle of 4, divide by 12 and get 1/3.

  • Square the result of Step 1. So keeping with our roof pitch of 4 this gives us 1/9.

  • Add 1, then take the square root. Adding 1 gives us 1 + 1/9 = 10/9, then taking the square root gives us about 1.0541.

  • Multiply by the square footage of a single floor of your house. So continuing our example, if you’ve got a two story house with a total square footage of 2,700 square feet, with each floor having 1,350 square feet, multiply 1,350 by 1.0541 to get 1,423 square feet. So you’d need 1,423 square feet of roofing.

  • Things You Will Need

    • Square footage of your house

    • Pitch of your roof

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    Calculating The Area Of A Complex Roof

    Areas of complex roofs with multiple hips and valleys take the most time to calculate. Start by making a rough sketch of the roof. To simplify the calculation, break down the sketch into rectangles and right triangles , then take as many measurements of the roof as you can to match the sides of the rectangles and triangles on the sketch.

    Use visual cues from the existing roof shingles or roof sheathing to determine square lines off eaves edges or ridges. These cues will help you measure the lengths of the sides of the rectangles and triangles. For instance, the cutout slots on shingled roofs run perpendicular to the eaves, and nail rows in sheathing are pretty close to square also. It is difficult sometimes to get accurate measurements. Dont get too concerned though just round lengths to the nearest 6 in.

    With the sketch filled in with measurements, you can determine the size of the roof area. The area of a rectangle is length multiplied by width, whereas the area of a right triangle is the length of the two sides that meet at the 90-degree corner multiplied together and divided by two .

    Tally the square footages of all the rectangles and triangles, which will give you the total square footage for the roof. The example here shows the calculation for a roof with two hips.

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    How To Measure Your Roof Area From The Ground

    Roofing Calculator

    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 roofs 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, youll need to work with a roofer or measure from on top of the roof itself to calculate its total area.

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    How Many Bundles Of Shingles Will You Need

    The average bundle of shingles covers 33.3 ft2, so three bundles of shingles are needed per square. Asphalt shingles range in price from about $25 per bundle for a standard 3-tab style to around $50-$75 or more for an upgraded architectural style.

    Since transportation is a major cost factor, expect prices to vary by location. A typical bundle of shingles weighs about 75 pounds, while some premium products can weigh over 100 pounds per bundle, so consider delivery of materials.

    Calculate The Simple Roof Areas

    On a simple hip or gable roof, multiplying the eave to ridge length by eave length will give the area to be multiplied by pitch factor. Ridge vent openings are best finished with coil rather than partial shingle. Using flat coil stock allows the ridge caps to lay flat and can also be formed with an extra water stop at the ridge opening.

    Area for the roof in Figure 3 is 1784 ft2 The blue dash line divides the roof into 2 rectangles. There is a small area calculated as 8/12 that is actually 4/12. On a small area such as this, it is better to err on the side of the higher pitch since it should not significantly affect the total.

    Pro Tip: Pythagorean Theorem can be used to calculate the length of the valleys. A general rule of thumb is to add at least 12 lineal inches of valley material to be safe.

    Figure 3. Calculating Simple Roof Areas

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    Calculate Roof Pitch From The Ground In Three Quick Steps

    Roof pitch is one of those things that middle school math and geometry instructors can easily point to, and say, See? Learning how to work with rise over run is fun and useful, right? If at any moment you start having PTSD flashbacks to algebra or geometry class, take a deep breath. Well walk you through this slowly in three simple steps. All you need is a tape measure, and possibly a helper to hold it.

    Step One: Grab that tape measure, notepad, and pencil and head outside. Find the slope of your roof youd like to measure, and start measuring the distance from the outer edge of the eave to the point at which the plane of the roof slope is barely visible to your eye. Write that number down in both inches. This figure is the horizontal run.

    Step Two: Stand directly underneath the gutter or edge of the roof plane you want to calculate the slope for. Measure the distance from your eye to the top of the drip edge of your roof overhang. Write that number down in inches, too. This figure is the roof rise.

    Step Three: Take the roof rise figure in Step Two and divide it by the horizontal run from Step One. In the example above, the rise is 60 inches and the run is 120 inches. This reduces down to a roof pitch of 6/12. Well use this figure in just a bit, so keep it handy.

    How Many Squares Per Roll Of Underlayment

    How To Measure The Square Footage Of A Roof With Google Earth. Measure A Roof For Metal Or Shingles.

    The roll size depends on the type of underlayment product. Synthetic underlayment comes in 10 square rolls, while regular #15 felt comes in 4 square rolls.

    So for the 24 square roof example, you would need 2.4 rolls of synthetic underlayment, or 6 rolls of regular #15 felt.

    • 24 squares ÷ 10 squares per roll = 2.4 rolls of synthetic underlayment
    • 24 squares ÷ 4 squares per roll = 6 rolls of regular #15 felt

    Remember: Add 10%-15% for the waste factor on underlayment, as well.

    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.

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    Finding The Size Of The Roof In Squares

    Roofing contractors estimate projects and materials by the square, so it is crucial to find this measurement to estimate the amount of material needed accurately. A square simply refers to a 10 x 10 square of roofing. This is simply 100 square feet of roof.

    To find the squares, divide the overall roof area by 100 and then round up. For instance, if the roof is 1550 square feet, then it is 16 squares.

    How To Measure A Roofing Square

    Starting a new roofing project can introduce homeowners to many roofing-specific terms, and one of the first you’re likely to come up against is “roofing square.” Measuring in squares is unique to the roofing industryfor homeowners, understanding how these measurements work can be an unfamiliar but vital part of planning for your roof repair or replacement.

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    How Do You Calculate The Square Footage Of Your Roof

    Is it time for a roof replacement? Are you trying to figure out how much youll have to invest in your new roof?

    If so, youre probably overwhelmed trying to learn everything that goes into the cost of your roof replacement. To help you understand the size of your roof investment, you first need to know the size of your roof. Thats why were going to break down how to measure your roofs square footage.

    The team at Bill Ragan Roofing has been repairing and replacing roofs in Nashville and surrounding areas since 1990. We take extreme pride in everything we do, especially our workmanship.

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