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How Do You Calculate Roofing

What If You Have A Steep Roof

How To Calculate Materials for Roofing

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
  • How To Measure Roofing Materials

    How do I calculate the total cost of roofing material? Simply calculate the total square footage of the roof using the lengths and width . A x B = 120 x 100 = 12,000 square feet. Is metal roofing measured in squares? The square foot is 100 square inches in real life. Roofs are typically measured in squares rather than yards or feet. The square footage of a roof is what determines its surface area rather than its height or depth. What are the dimensions of metal roofing? The length of the corrugation is between 1.25 and 4 inches. They are available in 18 gauges, 22 gauge, and 24 gauge sizes, as well as 27 gauge and 46 gauge sizes. The 42-inch panel can cover 8 to 10 feet in length, while the 27-inch panel can cover up to 20 feet in length.

    How To Calculate The Square Footage Of Your House

    A house that sounds roomy and spacious online may actually have 800 of its square feet contained in a four-foot-tall dirt-floor basement. Whats up with that? In Washington DC, clients are often confused at the square footage discrepancy between whats listed and what they see on tour, and colleagues in other markets hear similar things.

    Why the conflicting information? Well, the American National Standards Institute guidelines on how to calculate a homes square footage are considered the standard, but there are no official laws that govern this process. In addition, some Multiple Listing Services report all finished and unfinished square footage of a house as a single number, adding to the confusion. Since the rules arent standard, some listing agents just post their best guess on a homes square footage. As a result, buyers and their agents often have to investigate.

    If you love a home, does it matter if the 2,000 square foot charmer turns out to be officially 1,600 sq ft in length? Since square footage is used to determine a homes market value, it can matter a lot. When it comes time for you to sell, 400 fewer feet in measurement can impact the price youll get, particularly in a buyers market. Which is why we created this guide on how to calculate square footage of a house.

    Also Check: Does A New Roof Lower Home Insurance

    How Roof Pitch Is Calculated

    To accurately calculate the area of your roof, you must first determine its slope, or pitch. A roofs pitch is determined by how much it rises vertically for every foot it runs horizontally. Thus, a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. A 12 in 12 pitch is a steep, 45-degree angle roof. See the image below for more explanation on rise, run and pitch.

    How To Measure Your Roofs Square Footage

    How to Calculate Roof Square Footage? What

    The square footage of your roof has a huge impact on the cost of your replacement. It affects a number of cost factors, including the amount of materials used, labor, and time.

    Be aware, the only way to get a 100 percent accurate measurement is to have a local roofing contractor come out to professionally measure your roof and give you a quote. However, I can give you the calculations to get a rough measurement of your homes square footage.

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    How Do You Determine The Slope And Height Of A Roof

    The slope of a roof is determined by the rise over the run in other words, the amount of change in elevation divided by the horizontal distance. To find the slope, you will need to measure the height of the roof at two different points, and then divide that number by the horizontal distance between those points. The height of the roof is simply the vertical distance from the eaves to the peak.

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

    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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    What Is A Bundle Of Shingles

    A package of roofing shingles is called a bundle.

    How many bundles of shingles per square?

    Laminate or architectural shingles, one of the most common types of roofing shingles, are generally packaged in three bundles per square:

    3 bundles = 1 roofing square

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

    Here are a couple more examples:

    What About The Waste Factor Should I Order Extra Roofing Materials

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

    You want to order extra material to account for waste. Waste factors vary.

    10%-15% is a good rule of thumb, but your results may be different. More complicated roofs will have a higher waste factor because there are usually more cut shingles around corners, walls, and edges.

    It is okay to have a few shingles left over. They can be saved in case there is roof damage later or if repairs need to be done in the future.

    So for the 24 square roof example, you would want to add 2.4 squares which equal about 7 or 8 more bundles.

    Also Check: How To Calculate Metal Roofing

    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.

    Why Should I Measure My Own Roof

    If you plan on re-roofing your own home then you will need to calculate materials so you wont waste your own time and money. If youre like most people, youll need to hire a professional.

    Knowing your numbers will help you figure out what roofing materials are within your budget and having your square footage handy is a great way to protect yourself from inflated quotes.

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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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    Schedule Regular Inspections With A Roofing Contractor

    This is part 2 of our Roof Pitch guide. In the first part, weâve ...

    The old adage is that “an ounce of prevention is worth a pound of cure.” The speaker very well may have had the roof in mind. An experienced roofing contractor can spend an hour on your roof every year taking care of minor issues that left unattended, might result in hundreds of dollars of interior damage to your home. The contractor can also provide you with advance notice of when to start budgeting for a new roof and help you choose from the many types of roofing materials available today.

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    What Is A Roof Pitch Multiplier

    A roof pitch multiplier, also known as a roof pitch factor, is a number that, when multiplied by the area covered by a sloped roof, gives the actual area of the roof. The math behind this number is that it is the square root of 2 + 1). Roof pitch multipliers are extremely useful in estimating the amount of material required to fit your new sloped roof, as conventional mathematics will leave you short!

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    Factors That Affect Roofing Prices

    The cost of your roof is determined by various factors.

    Raw materials, processing costs, and designs of the roofing panels affect their pricing. Aluminum and Galvanized Steel are more common in residential roofing due to their top performance and affordability. Stainless steel, copper, and zinc, provide exceptional performance but are too expensive for most people.

    Interlocking panels have a more comprehensive production process, have more structural features and require more room on a shipping truck, thus cost more than overlapping panels. Panels that interlock on four sides produce better quality finish and cost more.

    Accessibility and physical location determine the required special licenses, permits and specialized equipment to fit in tight spaces. It will cost more to install a roof near power lines and tree branches.

    Complex architectural roof designs are more time consuming than simple designs due to fitting and angles. Windows, valleys, skylights, dormers, and chimneys increase material and labor costs. A steep roof pitch may require additional equipment and more time to complete while taller houses are more expensive due to the danger associated with height.

    A coating can radically transform the lifespan of your metal roof. Polyester based paints have a short lifespan and are the cheapest while Polyvinylidene Fluoride offers a remarkable lifespan, adhesion, and fade and chalk resistance.

    Also Check: What Is The Best Color Roof For Energy Efficiency

    How Do You Estimate The Cost Of A Metal Roof

    The 15,000ft2 / area is calculated using dividing the roofs area by the panels area and rounding it up. To find out how many numbers there are, multiply 256 by 8. Well need at least 8,438 metal panels to do this. If we purchased metal panels for $3 per piece, the total cost would be $3,438 x 8.438 = $25.31 per piece.

    How Much Does It Cost To Get A Roof?

    The average hourly cost of roofing labor varies greatly from state to state, but most roofing contractors charge between $40 and $80 per hour. A metal roof installation is typically priced between $7 and $14 per square foot, with the project typically charging the roofing square. To calculate your roof area, multiply your roofs length by its slope height and divide by two.

    What Is The Minimum Roof Pitch For Snow

    How To Calculate Roofing Shingles including Hip Roofs by PawPaw

    The minimum roof pitch for shedding snow is around 30°, or a 6:12 or 7:12 slope. However, this is not a definite, as the material of your roof, the direction of the snow and wind are some factors that can affect whether or not snow will slide, as roofs of as little as 10° have been reported to shed snow. Roofs of steeper pitches will likely retain less snow, so, if you live in snow-prone regions, a steeper pitch is highly desired.

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    Understanding The Roofing Calculator Inputs

    House Base Area – This is the surface area of the house, the parallel plan with the ground. You can simply calculate the base area of your house if it has a rectangular shape. However, for more complex shapes, you would either have to calculate each part of the shape individually or know what the area is priorly. If your house has a complex shape, the calculator would give more accurate results if you separate it into parts and calculate each part on its own.

    Roof Pitch – The roof pitch is measured as a ratio of the vertical rise of the house over its horizontal run. In the U.S., this ratio is shown as the number of inches of vertical house for every 12 inches of horizontal run. For example, if the roof pitch is 5/12, this means that the roof rises 5 inches for every 12 horizontal inches.

    Price – The calculator allows you to input the estimatedprice per square footof constructing the roof in order to find out how much would be needed in total to cover the whole roofs surface area.

    How To Measure Your Roof

    When it comes to calculating the amount of plywood you need to sheathe a roof, the old adage measure twice, cut once definitely applies. To determine the number of 4×8-foot sheets of plywood needed to cover the surface area of your roof, start by measuring its length and width in feet. Once you have those numbers, multiply them together to get the square footage of your roof. For example, if your roof is 30 feet wide and 40 feet long, its square footage would be 1,200.

    Once you know the square footage of your roof, divide that number by 32 . This will give you a good estimate of how many sheets youll need for sheathing. In our example, 1,200 divided by 32 equals 37.5 sheetsso youd need 38 sheets to cover a roof with those dimensions.

    Keep in mind that this is just an estimate actual coverage may vary depending on the type and style of roof you have. When in doubt, always err on the side of buying more plywood than you think youll needits easier to take unused sheets back to the store than it is to make a run for more in the middle of a project!

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    What Degree Angle Is A 12 12 Pitch Roof

    A 12/12 pitch roof has a pitch angle of 45°. To convert between American roofing ratios and pitch degrees, follow these steps:

  • Divide the first part of the ratio by 12 to work out the pitch.
  • Find the inverse tangent of the pitch to find the angle in degrees.
  • Check your results with the Omni Roof Pitch Calculator.
  • at your mathematical prowess.
  • What Roof Type Is Best Suited For Your Roof Pitch

    Calculating the Amount of Roof Tiles &  Slatesï½Roof Stores

    If you have roof pitch of 3/13 or lower, it is highly recommended that you use/install a flat or low slope roofing .

    If your roof slope is above 3/12 , you can install either asphalt shingles, or a metal roof, or one of the exotic roof types: Slate, Tile, Wood, etc.

    Metal roofs have the highest wind blow-off resistance, and are best suited for ice dams prevention especially if your roof slope is below 6/12!

    Read Also: How To Roof Over Shingles

    Good Better Best Bid For Roofing

    Knowing how to achieve a particular margin is important, but it doesnt help you decide which margin will work best for your business. Instead of picking a single margin, offer your clients three , and see what they choose. This strategy is called good, better, best pricing.

    There are a few different ways to accomplish this pricing scheme. You can offer homeowners different shingle and underlayment combinations, making three discrete packages. For example, a customer who wants a premium shingle, like IKOs Crowne Slate, will pay the best prices. On the other hand, an elderly couple who have traditional tastes and are on a tight budget might prefer a good package with IKOs 3-tab shingles. So, you might present your bid with three packages that look like this:

    • Good Package: 3-tab shingles. Cost: $1,052.
    • Better Package: Architectural shingles, and superior cleanup services. Cost: $1,311.
    • Best Package: Premium Designer shingles, higher-end vents and accessories, superior cleanup services and second roof inspection. Cost: $1,876.

    Youre not only adding on the price of the higher cost shingles, but youre also adding a higher margin for each package. Perhaps you can see the rationale already: Though these numbers are made up just to serve as an example, you can see that its a much lower jump to the better package than to the best. You can see the value of the higher-end packages and so can your client.


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