Roofing Pitch For Square Roof Area
Finally, the more complex part, measuring your roofs pitch.
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.
Determine The Roof Slope Multiplier
Note: If you already know the roof slope in degrees, then all you have to do to find the roof slope multiplier is find the secant using a scientific calculator.
For example, if the roof slope angle is 45°, then sec = 1.414213. That will be your roof slope multiplier.
So, to proceed.
Once you have the slope of the roof expressed in standard pitch, you can consider yourself in possession of the lengths of the a and b sides of a right triangle. Now you need to pull out your trusty Pythagorean Theorem and figure out the length of the hypotenuse.
A good calculator can be found at web2.0calc.com.
As Im sure you remember, a² + b² = c². So, if your slope is 6:12,
6² + 12² = c²
36 + 144 = c²
13.416 = c
So 13.416 is the length of the hypotenuse.
Now that you have the length of your hypotenuse, 13.416, you want to think of that as the length of a line on the actual sloped roof surface over a horizontal distance of 12 inches. You want to find out how much longer that line is than the 12 inches it covers.
You will express this difference as a number, called the roof slope factor .
Once you know the roof slope multiplier for any particular roof slope, you can use it to find the actual area of a roof of any size that has the same slope.
So in this case, for every 12 inches the roof goes across horizontally , while rising 6 inches , theres actually 13.416 inches of roof .
If you divide the 13.416 inches by the 12 inches , that gives you 1.118.
Whats Your Roof Slope
You will also need to know the slope of your deck.
To determine this, measure the vertical rise of your deck in inches over a 12 horizontal distance.
If this rise is 4, then your roof slope is 4 in 12.
Roof slopes are always expressed with the vertical rise mentioned first and the horizontal run mentioned second.
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How To Measure A Roof For Shingles
August 28, 2019 By Taylor-Made Roofing
Whether youre re-roofing your home or purchasing shingles for a brand-new house, its important to understand that a successful roofing project often requires a significant investment of both time and money. As you begin shopping for materials, you might wonder how to measure a roof for shingles. After all, roofing materials vary greatly in cost and are priced per square foot. To determine the size of your roof, contact a professional roofer who can measure your roof and provide an estimate for the roofing project.
Calculate The Surface Area Of The Roof
Take the area of a roofs footprint, say its 5,000 square feet, and multiply 5,000 by 1.118.
That gives you 5,590 square feet, which is the actual area of the surface of the roof. And thats what you were looking for.
This applies to rafter lengths as well as areas. A rafter for a roof with a 6:12 slope will be 1.118 times as long as the horizontal length that it covers.
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Estimating Roof Area Using Pitch And Square Footage
If you are mathematically inclined or have a roofing calculator, you can estimate the roof area if you know the pitch of your roof and the square footage of your home. To illustrate, if your pitch is 4/12 and your two-story home has 1,400 square feet on each floor, these are the calculations.
Divide the pitch. For a 4/12 pitch, the answer is 1/3. Square the above answer, which in this example would yield 1/9. Add 1, expressed as a fraction. That is, you would add 9/9 + 1/9 for a total of 10/9. Take the square root of 10/9, which is approximately 1.054. Multiply 1.054 by 1,400, the square footage of the home used in this example. You should get 1,475.6. Divide 1,475.6 by 100 to determine the number of squares required. You will need at least 14.756 squares of roofing. However, you should add about 10 percent for starter strips, valleys, waste and hip and ridge.
Expressing Slope In Standard Pitch
Note: All of these calculations work the same whether you are using inches or centimeters. You just have to plug the numbers in. A roof that rises 10 cm for every 30 cm of horizontal distance has the same slope as a roof that rises 4 inches for every 12 inches of run.
In the U.S., the slope of the roof is typically given in standard pitch, which is a ratio expressed as rise-in-run, X-in-12, or X:12.
Traditionally, 12 is always used as the run, because there are twelve inches in a foot, and you are stating how many inches the roof rises vertically for every foot the roof spans horizontally.
Pitched roofs commonly have slopes between 4-in-12 and 12-in-12 . A roof that goes up at a 45-degree angle has a slope of 12:12.
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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.
S To Measuring Roof Square Footage
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How Do You Calculate Roof Squares
Roof surfaces are measured in squares. A square is an area of roof which measures 100 square feet. To determine the number of squares on the gable roof above, simply divide its total of 24,000 square feet by 100. The result is 240, and this means you would need 240 squares of shingles to cover that roof.
Calculate The Square Footage Of The Roof Area With The Roof Pitch And Base Area
Find your roof pitch from the first step in the following table and multiply the amount you just got by the corresponding roof pitch multiplier. The result is the total roof square footage youll need to get roofing material for.
In our example, the roof pitch was 6/12. The pitch multiplier would be 1.118. So, take the 2100 square feet, multiplied by 1.118 to get 2347 square feet of roofing material. Since roofing material like shingles come in squares of 100 square feet apiece, wed need at least 24 of them. If you have a relatively flat roof , you can simply avoid using a pitch multiplier and make sure to round up on your equipment estimate.
Roof Slope |
1.414 |
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Calculate The Square Footage Of Your Roof
After considering 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:
56′ x 28′ = 1,568
1,568 x 1.3 = 2,038
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. After getting your roofs rough square footage, put that number in our free Roofing Calculator to get an idea on the cost of your new roof.
How Many Squares Per Roll Of Underlayment
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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How To Calculate Number Of Roofing Shingles
Fortunately, you don’t 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 squareit’s 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 you’ll 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 you’re 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 home’s style. Be sure to keep local building codes in mind as you weigh your shingle options..
How To Measure Residential Roof Plans
The first thing to check is what scale the roof is drawn in. The roof below is drawn in 1/8 scale This means that, if using a regular tape measure that 1 inch would equal 8 feet. In this drawing a 1/8 scale ruler is being used. The next thing to determine is the roof pitch see The easiest and most accurate method to measuring a roof plan is to square everything off.
This means that you want to divide the roof into sections. Notice the bold dotted line this dotted line separates the main roof from the gable pop-out on the front of house. With this method only 2 calculations are needed. Measure all the hips, rakes, and valleys.
Add for pitch. Measure all the eaves and top ridge. Just add for roof pitch and you have a complete takeoff Determine how much add for roof pitch
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Two: Split Tricky Shapes Into Squares And Rectangles
Once you have these figures, return to the safety of your home. Notice in the image above, the hip roof is made of two triangles and two trapezoids. Trapezoids are tricky to get the area measurement of, so were going to split each of them into two triangles and a rectangle:
We know enough about the overall measurements of the roof to fill in the missing values. Lets fill the figures in now:
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.
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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.
Expressing Roof Slope In Degrees
The rest of the English-speaking world uses degrees, which seems simpler, but it takes a few extra steps to figure it out mathematically.
It also doesnt immediately convey as much information about the roof on a practical level as the rise-in-run ratio expression.
To express the slope in degrees, you divide the rise by the run and find the inverse tangent of the result.
But you still need to know the rise and the run, the X-in-12, in order to find the roof slope in degrees, unless youre using a slope finder that tells you the slope in degrees.
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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.
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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How To Measure Your Roof Area From The Ground
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.