Tips For Calculating Roof Area So Youll Know How Many Bundles Per Square Youll Need For Roof Area Coverage
So you need a new roof, whether its to adorn your newly built home or to replace your existing roof. Like most North Americans, youve wisely decided to go with asphalt shingles due, in large part, to their vast range of styles and color blends. Like most of your neighbors, you plan to have the shingles installed by a professional roof contractor who will handle all the material calculations however, the information below will help you understand how to estimate the amount of shingles and accessory materials you need for your roof.
Calculating how many shingles you need for your roof is very similar to calculating how much carpet you need for your floors or how much wallpaper you need for your walls simply determine the area of the roof and divide by the area covered by each package of shingles.
Sounds simple, right? The only hard part is getting the actual measurements, and there are various ways to do this. Most likely, the roofer will physically get on the roof and, using a good old-fashioned tape measure, measure the areas of all the various roof sections and total them together. Of course, if the house is a new construction, these values will be readily available from the architectural drawings.
When Is The Worst Time For Roof Replacement
Many home improvement experts recommend that the overall best time to get a new roof is in the fall. If you poke around the internet for advice, the fall season is most likely going to be a highly popular suggestion.
However, as you will learn in this post, fall is actually one of the worst times to get the job done. Roofers recommend it, because this is the time they can charge premium for their services.
What is a better alternative?
The short answer is: get your roof installed during the SLOW season for contractors.
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Calculating How Many Shingles You’ll Need
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Figure Out Your Homes Footprint
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.
The Shingles Are Curling
Shingles can curl in two ways: There’s cupping, which happens when the edges of the shingles turn upward and there’s clawing, which is when the edges stay flat and the middle starts to come up. “Both are signs of weathering and indicate that problems potentially leaks are relatively close to fruition,” says Mark Graham, vice president of the National Roofing Contractors Association.
How much time you’ve got left: “Depending on the extent of the curling, it could be anywhere from a year to five years before you need a new roof,” says Graham.
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How To Measure A Roof Using Google Earth
If youre looking for a free way to measure your roof using imagery you can find on a smartphone or computer, consider logging into Google Earth and searching for your home. If you live in a large enough metropolitan area, youll find both the 2D and 3D imagery needed to take roof measurements online.
Begin by entering your address into Google Earths search function. Youll get a birds-eye 3D view of the property, which will allow you to get a good view of the roof pitch. Position the view, so youre looking down on the roof.
Use Google Earths area measurement tool to outline the section of roof you want to measure, making sure to set the display to feet. Once you create a box, Google will tell you the length of each side and the total square footage.
You can use that number with the slope factor of your roof to come up with a fairly accurate estimate.
This method isnt as precise as the expensive apps, but it will give you a good enough estimate of the square footage of your roof to purchase shingles.
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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How Many Nails Will You Need
Nails will also be required for any roofing project. The average 3-tab shingle needs four nails per shingle. High wind areas and other types of shingles may need more. 320 nails will be needed to install a square of standard 3-tab shingles, assuming four nails per shingle and 80 shingles per square.
How Many Roofing Shingles Do I Need
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:
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:
- 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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How Long Does A Roof Last
Are you aware of the condition of the roof over your family or employees?
If you own a property, you should be.
Most of the time, property owners dont realize that their roof is beyond repair until it is too late.
Whats more, many property owners dont really know how long a roof lasts or when to replace a roof.
In this guide, youll get answers to this question how long should a roof last?
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Your Asphalt Roof Fails Prematurely
Your roofing materials should live as long as the manufacturer specifies. However, there are cases when your roof fails prematurely and leads to a roof replacement well before you should need one.
When your roof wasnt installed using correct roofing techniques youre going to find shingles in your yard or even full sections sliding off your roof. If your attic wasnt properly ventilated then the damage from the trapped heat and cold will drastically shorten your roofs life.
Be aware, when your roof isnt properly ventilated or properly installed the manufacturers warranty on your roofing materials will be voided. This leaves you with only your contractors workmanship warranty to fall back on to replace your prematurely failed roof.
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Plan For Waste Factor
The only roof that will generate no waste from cutting is that rare simple gable whose roof length is divisible by the 3-ft. length of a shingle. Other simple gable roofs will require cut shingles at the rakes. From there, the waste factor increases with every obstruction, such as a chimney, and with every hip or valley.
Laminated shingles typically generate less waste than three-tab shingles do because you dont have to maintain a cutout pattern, but its tricky to determine exactly how many square feet of shingles you will be able to salvage. Its best to plan your order using the same waste factor that you would use for three-tab shinglesat worst youll just have a couple of bundles to return.For a simple roof, I generally figure 1 percent as a waste factor. On a complex roof with open valleys, I add 5 percent and sometimes more. Theres no calculation you can use to determine the extra shingles youll need for waste. With experience estimating jobs, youll get a feel for how many extra shingles to order.
Waste is also generated when shingles are damaged, which is inevitable when youre moving shingles around a steep roof slope and some will slide off. You may be able to salvage part of the damaged shingle, but dont count on it. You can also waste shingles when you nail them improperly and have to remove them. You may drive nails too low in the exposure or fasten one off a control line.
Potential Signs That Your Roof May Need To Be Replaced:
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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.
How Do I Measure A Steep Roof
Most roofers wont go on a roof with an 8/12 roof pitch or greater with special equipment such as scaffolding and roof jacks and neither should you. Instead, use one of the four methods described above that allow you to measure the roof while standing safely on the ground or from the comfort of your computer.
While these methods may not be quite as accurate as taking actual measurements from the rooftop, theyre close enough for calculating how many shingles youll need to purchase for a new roof.
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You Can See Sunlight From Your Attic
You don’t need us to tell you that this isn’t a good sign because it’s not! If light can get in, so can rain, cold air, and snow. Check for light and also look for water stains. “If you find any, watch them over a few rainfalls and if they change shape or size, that means you’ve got an active leak,” says McGavic.
How much time you’ve got left: It depends on the extent of the damage, so call a pro. Small leaks can be patched, but larger ones, structural damage, and the age factor might make it wise to replace your roof sooner rather than later
Calculating The Area From The Building’s Square Footage
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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.