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.
Potential Signs That Your Roof May Need To Be Replaced:
August 28, 2019 By Taylor-Made Roofing
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.
What Depth Of Gravel Do I Need
You would usually lay a 10mm aggregate at a depth of 30-40mm, but on a driveway this would need to be at least 50mm. A 20mm aggregate would need to be at least 40-50mm deep, and at least 50-60mm on driveways. A larger aggregate will settle and bond together better than smaller ones. The depth you will need to select for your gravel or slate will always depend on the aggregate size and what the surface will be used for.
How Do You Calculate The Square Footage Of 1010 Shed Roof
Figure out the area of the shed plus the overhangs:- determine the squre footage of the shed foot print by measuring the length and width of the shed including the overhangs. Assume the overhangs are 1 feet both sides eves and rake then you have 2 feet extra, so each dimension for 10×10 shed roof with overhangs is around 12×12 = 144 square footage.
Find the roof pitch or slope:- the roof pitch is the amount of slope. The slope is described by the rise in inches or how far up it goes over the run in inches or how far horizontal it goes. We will use a 6 in 12 pitch. For every 6 inches the roof goes up to the peak it goes 12 inches horizontally.
Calculate the square of rise and run and sum it:- square of rise 6×6=36, square of run = 12×12 = 144, add both 36 +144 = 180.
Find the square root of the sum:- square root of 180 = 13.417
Sum divide by 12 to get the product:- square root of 180 = 13.417 is divided by 12 as 13.417 ÷ 12 = 1.118, hence 1.118 equals the product
Multiply the product by the flat roof area and divide by 100:- our 10×10 shed square footage with overhangs is 144 sq ft, so 1.118 x 144 = 161 square feet, 161 / 100 = 1.61 squares.
Add 10% for wastes:- wastages 10% of 1.61 squares = 0.161, so final squares of shingles do you need = 1.61+ 0.161 = 1.8 squares, it is rounded to 2 squares.
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How Much Do Shingles Weigh
To calculate shingle weight, youâll need to understand bundles and squares. A square of shingles is a roofing term for 100 square feet of material. It typically takes 3 bundles of shingles to cover a square of roof. While youâll hear both terms, bundle is more commonly used when purchasing shingles, while square is associated with a completed roof or shingle removal.
Keep in Mind: The exact weight per bundle or square of shingles depends on the manufacturer. Also, remember that older shingles will weigh less as they are worn down by the elements over time.
Measuring The Area Of Your Roof
The area of a roof is actually a fairly straightforward calculation, though if you dont have the technical drawings to hand getting the original measurements may be a bit tricky. You will need to the full length along its long edge as well as the length of your roofs slope. Think of these two measurements as the horizontal and vertical sides of a rectangle. Simply multiply them for an estimated area. Remember to then double this number to account for the other side of your roof. If you roof is made up of multiple slopes and valleys, we would suggest separating each into an easily recognisable rectangle, calculating all of the individual areas and then adding these together for your final result.
Due to the difficulty involved in determining these measurements by hand, we would recommend either hiring a professional for a complete and accurate estimation or find yourself a laser measure. This will still involve some manual labour but will make an easier job of getting these numbers.
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How To Calculate Number Of Roofing Shingles
Fortunately, you dont 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 squareits 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 youll 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 youre 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 homes style. Be sure to keep local building codes in mind as you weigh your shingle options..
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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.
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Plan For Extra Valley Material
Valleys are either woven or cut both methods require about the same number of shingles. On a woven valley, each course of shingles is extended beyond the valley crease and at least 12 in. onto the adjacent roof plane. Youll use 2 ft. of extra shingle material for each pair of woven courses. In the case of cut valleys, the shingles from the first roof plane thats shingled also extend onto the adjacent roof plane at least 12 in. just like woven valleys. Shingles from the next roof plane are cut just up from the valley line, and the cutoff pieces usually arent big enough to use elsewhere on the roof. Order two extra shingles per linear foot of valley to account for the overlaps and cutoffs. On a 16-ft. valley, you would need 32 shingles or roughly one extra bundle.
How Many Shingles Do I Need For A 2424 Garage
For this example, well use the same type of roof a simple gabled roof. For our purposes, well say that the roof extends 1.5 around each side.
Well first calculate one face of the roof. The length of the roof is 24+1.5+1.5, which equals 27. The roof pitch is 4:12, which means the width of the roof is about 12.5. Add 1.5 of overhang to this number and you get 14 of roof width on one roof face.
Multiply 27 by 14 and you get 378 square feet for one roof face. The total roof area is 756 square feet. Divide this number by 100 to determine the amount of roof squares youll need, which equals 7.56 roofing squares.
Multiply 7.56 roofing squares by 3 bundles per square. Thus, 23 bundles of shingles are required to cover a 24×24 garage with 1.5 overhangs on all sides.
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Measuring The Length And Width Of Each Plane By Hand
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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Calculating How Many Shingles Youll Need
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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Can You Install A New Roof On Top Of Old Shingles
Many homeowners wonder whether or not its a good idea to install a roof on top of existing shingles .
The biggest reason for keeping the existing layer of old roofing is obvious extra cost. As we just explained above many people would rather avoid spending an additional $1,000 on removing the old shingles.
Despite the high cost, doing this is absolutely essential! Leaving the old material will greatly accelerate the disintegration of the new roof and shorten its life cycle.
This is because ventilation is reduced, which in turn increases the average temperature of the shingles, causing the product to dry up quicker and the granules to start falling off faster.
Another reason why you should NOT leave the old shingles is because a roofer will typically not install underlayment between old and new roofing. If there are pre-existing problems in the leak prone areas: such as skylights, chimneys, vents and valleys, installing new shingles will not solve them! This means that your new roof will continue to leak.
Failing to tear off old roofing will also negatively impact your warranty. Most large shingle manufacturers explicitly state that your material and labor warranty automatically becomes void, if their product was installed on top of an old roof.
In most states, the building codes require that you remove the old roofing materials, if there are more than two layers of it already there.
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