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How Do You Figure Square Footage Of A Roof

So What Is A Roofing Square

How to Measure the Square Footage of a Roof

A roofing square is a measurement, but it has nothing to do with square feet, meters, yards, or miles. A roofing square is commonly used by roofing companies and is roughly equivalent to 100 square feet. This measurement does not change whether it is a square of shingles or a square of tarp. This is because roofing squares are used to make calculating the cost of materials and labor easier than if you had to use square feet or yards.

Calculating Gable Height Knowing Wall Length And Roof Pitch

This calculation is done using the same units. Using mixed units, like feet and inches, can make it hard to do the calculation.

gable wall-length = 24 feet roof pitch = 6 : 12 a 6-inch rise for every 12 inches of run

Take half the length of the gable wall and divide this by the run of 12 inches

288 ÷ 2 = 144
Half the gable wall has a length of 144 inches.

Measured from outside to the centre of the gable, at 144 inches, is the location of the peak. At this location is the highest point of the gable.

Calculate the number of 12-inch runs that there are in 144 inches

144 ÷ 12 = 12
The total area of the gable is 72 square feet.
gable wall-length = 34 feet 3 inchesroof pitch = 5 : 12 a 5-inch rise for every 12 inches of run

Get rid of the mixed units used for wall length

34 * 12  = 408 + 3 = 411
34 feet 3 inches = 411 inches
411 ÷ 2 = 205.5
Half the length of the gable is 205.5 inches.
205.5 ÷ 12 = 17.125
There are 17.125 x 12-inch runs in 205.5 inches of wall length.
17.125 * 5 = 85.625
The gable at the centre has a height of 85.625 inches = 7 feet 1 5/8 inches.
Calculating the gable’s square footage
gable wall-length = 34 feet 3 inches wall height = 7 feet 1 5/8 

Again, divide the gable wall length in two, creating two triangles. Join the two triangles to form a rectangle.

This rectangle shape has a length of 205.5 inches and a height of 85.625 inches. Multiply the length by the height

205.5 * 85.625 = 17595.9375 rounded to 17595
17595 ÷ 144 = 122.1875 rounded to 123

Tips For Getting Started

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

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Average Shingle Roof Cost Calculations

The average 2,000 square foot single story home will range from $9,000 to $11,000 or more depending on the type of shingle used. Additional factors that could lead to higher cost are how steep your roofs pitch is and the amount of dormers that have to be worked around.

Generally speaking, roof cost will be different between manufacturer type and grade of shingle. For example, architectural shingles are twice to three times as thick and will cost more than standard asphalt shingles, while GAF shingles will generally be more expensive than IKO shingles, with warranty coverage matching price. As a general rule of thumb, the more upfront investment in a roofing material, the longer the manufacturer warranty, with GAF offering up to a 50 year warranty for installations.

Convert Among Square Inch Square Foot Square Yard And Square Meter

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

You could, for example, perform all of your measurements in inches or centimeters, calculate area in square inches or square centimeters then convert your final answer to the unit you need such as square feet or square meters.

To convert among square feet, yards and meters use the following conversion factors. For other units use our calculator forarea conversions.

  • Square Feet to Square Yards
  • multiply ft2 by 0.11111 to get yd2
  • Square Feet to Square Meters
  • multiply ft2 by 0.092903 to get m2
  • Square Yards to Square Feet
  • multiply yd2 by 9 to get ft2
  • Square Yards to Square Meters
  • multiply yd2 by 0.836127 to get m2
  • Square Meters to Square Feet
  • multiply m2 by 10.7639 to get ft2
  • Square Meters to Square Yards
  • multiply m2 by 1.19599 to get yd2
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    Make The Calculations For Your Roof Pitch

    A roofs pitch is its slope. Lower pitch generally means an easier install, which means a lower price. Low pitches rise three inches every foot of roof length, while medium pitches rise 6 inches every foot and high pitches rise a foot for every foot of roofing.

    In order to properly calculate the total pitch of your roof, youre going to need a ladder, a tape measure and a level. What youre going to want to do is measure up the roofline by one foot. Make sure to set the edge of your level at that spot . With the level in place, tip it so that its completely level from the spot you measured to out over the edge of the roof. From the end of the level, measure downwards to the bottom edge (so that your measurement goes to the bottom of the roof.

    Whatever the total vertical distance is, is the overall pitch of your roof.

    So to recap: the level should be one foot in total length or more. Use your measure to measure up your roof from the base up 12 inches.

    Place the level at the 12 inch mark, outwards at a ninety degree angle. Measure downwards from the level to the roof baseline and youll have the pitch. 3 Inches is considered a low pitch, about 6 inches a medium pitch and 12 inches a high pitch.

    Keep The Slope And Complexity Of Your Roof In Mind

    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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    Who Uses Roofing Squares

    The roofing square size form of measurement is only used within the roofing and construction industries. Though you can use the measurement yourself to try to calculate the cost of re-shingling your homes, such tasks are usually best left to an experienced roofing contractor. Nonetheless, even if you have confidence in your ability to determine the correct amount of materials needed, there are still a few steps you should take before you try.

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    Calculate The Square Footage Of Your Roof

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

    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.

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    What About The Waste Factor Should I Order Extra Roofing Materials

    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.

    How To Account For Shingle Wastage

    There will always be a certain amount of wastage when constructing a shingle roof, but this can vary hugely depending on the shape of your roof and any extra features it has.

    For a complex roof with lots of corners, you can expect to go through more wastage and offcuts of shingles compared with a simple roof. Roofs with dormer windows or skylights will also have more wastage compared with those that dont, as you will need to make more cuts in the shingles, and the leftover portions will be unusable.

    For any roofing project, you should buy between 10 and 15 percent more shingles than you have calculated. So for a roof that measures 20 squares, you should buy an additional 2 or 3 squares to account for wastage. This is because 10 percent of 20 is 2, and 15 percent of 20 is 3. If you are ordering your supplies in bundles, then this will mean you will want between 6 and 9 extra bundles, based on the fact that there are 3 bundles in each square.

    Although this might seem like needless extra expenditure, you dont want your project to be delayed if you run out of shingles and cannot get hold of more of the same ones immediately. It is always safer to have more shingles than you need as opposed to less.

    If you have shingles left over at the end of your project, you should save them for future repairs or replacements on your roof, so you wont have to have mismatching shingles.

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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
  • Find The Area Of The Footprint Of The Roof

    How Many Shingles In A Square Of Roofing

    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.

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    Why Is It Important

    A roofing square is an important measurement for roofers. It is the most common way to measure a roofs size. Roofers use this measurement to calculate the amount of material they will need to cover a roof. This measurement is also used to price a new roof. A roofing square is equal to 100 square feet.

    Roofers will measure the length and width of a roof and divide it by 100. This will give them the roofs square footage. Most roofs are not perfect squares, therefore this measurement may be difficult to calculate without a roofing square ruler or tool such as a credit card that is 100-square inches long.

    Measuring The Length And Width Of Each Plane By Hand

  • 1Draw an overhead view of your roof. Each area on the roof is a single plane, which just means its a surface with a 2D shape, like a rectangle or square. Add lines where the different planes come together. Make sure to include all the planes, as well as any shingled sides of dormers your roof may have.
  • You dont have to draw this to scale. You just need a basic drawing of what your roof looks like.
  • Draw the roof like flat planes. Dont try to add perspective for the pitch. So if you have 2 rectangles meeting together at an angle, just draw 2 rectangles with a line in between.
  • 2Climb a ladder with a notepad, a pencil, and a measuring tape. Stow these items in a shoulder or hip pack while climbing for easy access. Wear closed-toe shoes with good grip and avoid working on wet or windy days.XResearch source
  • Use a sturdy extension ladder and prop it against the side of the roof. Make sure the ground is level underneath if its not, use plywood to even it out by placing pieces under one side. Tie the ladder to stakes to steady it on the ground, and then tie it with wire to a 20d nail driven into the roof.
  • To step onto the roof, hold on to the ladder extending above the base of the roof with 2 hands. It should extend at least 3 feet from the base of the roof.
  • Read the measurement and write it down on the small map you made of the roof, putting the measurements on the correct sides as you do.
  • Always be careful to balance yourself while youre making measurements.
  • 5
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    Measure The Base Area Of Your Property

    Now, use that tape measure again and take the distance from the edge of one of the eaves to the other edge along the same wall. Record that figure in feet. That will be the roof base width.

    Then, measure the distance of the other side of the structure from the edge of the eave to the other. That will be the roof base length.

    Multiply those figures together to get an estimate of the base area for the roof structure. For example, if your roof base width is 35 feet and your roof base length is 60 feet, the total base area would be 2100 square feet.

    How Many Roofing Shingles Do I Need

    How to Calculate Square Footage | The Home Depot

    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.

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    Roofing Pitch For Square Roof Area

    Finally, the more complex part is measuring your roofs pitch.

  • Estimate or calculate the pitch of your roof .
  • Climb to the peak of your roof. Bring a two foot level. Hold your level outward, perfectly horizontal from your roof, so the bubble is in the middle of the indicator glass. Then, using a tape measure, determine how many inches are between the middle of your level and your roof. .
  • Multiply the number of roofing squares by the following digits below.
  • Low Pitch: 1.07 x Roofing SquaresMedium Pitch: 1.185 x Roofing SquaresHigh Pitch: 1.36 x Roofing Squares

    NOTE: We understand a roofs pitch makes this process somewhat tricky. Enjoy Home Advisors free roofing square calculator right here.

    What Is A Square

    The first step is to figure out the square footage of your roof’s surfaces which will involve a little math. Depending on the complexity of your roof this can range from a simple task to a complex combination of equations. For the purposes of this article lets just keep it simple and look at a two plane gable roof system.

    We were all taught this in high school, but the area of a surface is figured by multiplying the length by the width. If you do this for both sides of the roof and add them together you will find your total square footage of the roof.

    With this information in hand, we can then start to calculate how many squares of shingles we will need. In roofer-talk, 1 square translate to 100 square feet. So for an easy example lets say we have 2 seperate roof slopes that are 1000 sqaure feet each. That would give us 20 squares. At Prostruct we created a simple calculator to estimate the amount of squares a given roof is by using the liveable square footage.

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