## Different Materials Have Different Weights

Most homes have one of two different kinds of asphalt shingles on their roofs. There are three-tab shingles, a more traditional-looking specimen with a smooth, light-weight look, and architectural shingles, which are thicker and designed to give surfaces a textured appearance. As you might imagine, architectural asphalt shingles weigh much more than their three-tab counterparts.

However, those weights are typically nothing compared to the load from more specialized materials. Clay, slate, and concrete tiles all weigh more than asphalt, many times over. In general, asphalt hits somewhere around 2.5 to 3 pounds per square foot. On the other hand, a load of ¾-inch slate tiles might weigh as much as 26 pounds per square footso thats definitely a drastic difference. You can use a roofing weight calculator, like this one, to figure out how much each material you pull off will weigh.

Keep in mind that some roofs have multiple layers of shingles, so that can affect your weight as well.

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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.

## What Does It Measure

When it comes to roofing measurement, people talk about the square of roofing. A roofing square refers to a 10-foot by 10-foot section of the roof. So if a contractor quotes a price for 500 squares of shingles, they are referring to enough shingles to cover 5000 square feet of the roof. But why use this measurement instead of simply stating the number of square feet? This method brings efficiency to communication in the roofing industry- its much quicker to say, we need 20 squares of shingles rather than, we need 200 square feet of shingles. However, its important to note that a roofing square does not necessarily equal 100 square feet when taking into account the slope and other irregularities on your roof. So make sure you verify measurements with your roofing contractor before purchasing materials!

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## 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.

## Types Of Roof Coatings

GAF offers a variety of roof coating systems made with acrylic, silicone, and polyurethane. Below are the key features of each type of system.

**Acrylic coatings**are an ideal solution for structurally sound roofs in need of restoration. Products such as GAFs RoofMate coating can be used on a variety of substrates to help protect the substrate against weathering and UV damage. Additionally, some acrylic coatings systems are fabric-reinforced for an extra layer of protection.

**Silicone coatings,**like GAFs line of Unisil silicone coatings, help protect the substrate against weathering and UV damage while also providing protection against leaks due to ponding water. Silicone coatings provide strong adhesion to many substrates, and come in both high solid and low solid varieties.

**Polyurethane coatings,**like GAFs line of Elastuff coatings, provide an excellent balance of tensile strength, elongation, and hardness. Their hard finish makes them well-suited for installations that require high abrasion, impact, and chemical resistance.

**Also Check: How Much Does It Cost To Start A Roofing Company **

## Calculating How Many Packs Of Shingles You Need

With your roofs area and ridge length clear in your mind, the next step is to find the shingles you want to use. Lets take our customer favourite Coroshingles as an example. Each pack covers an area of 2m² with 14 shingle strips. With this, calculating the rough number of packs you need just involves punching the numbers into a simple formula:

*Roof Area/Pack Size*

Assuming the roof area was 50m², this specific example it would look like this:

*50/2*

This would give you a final answer of **25 packs.** However, that is just for the area of the roof. If you are also using shingles to cover the length of your ridge, you will need to determine how many strips are needed to cover the full run. This may require you to look at the width of the induvial strip to determine exactly how many extra packs you might need based on your initial ridge measurement. We would always advise rounding up, as this would help to account for any mistakes, wastage or off-cuts.

Also bear in mind that most shingles will require a detailing strip to be installed along the eaves first.

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## How Do I Calculate How Many Shingles I Need

**To estimate how many shingles youll need, you need to know the total square footage of your roofs surface. Find this number by measuring the length and width of each plane on the roof then multiplying length times width.**

Calculating the number of bundles, you need is simple if you are using shingles that come three bundles to a square. Each bundle covers 33.3 sq. ft. of roof areawhich is close enough to the 32 sq.

Thereof, How many bundles of shingles do I need for 100 square feet?

three bundles

Also to know is, How many square feet are in a bundle of shingles? 33.3 sq. ft.

Subsequently, question is, How many shingles do I need for a 24×24 garage? Additionally, how many shingles do I need for a 24×24 garage? Three bundles are equal to one square. Each square equates to 100 square feet. In the previous example, three squares, or 300 square feet, of shingles will be needed to cover the garage roof.

Also, How many bundles of shingles do I need for 200 square feet?

How Many Bundles of Shingles Will You Need. The average bundle of shingles covers 33.3 ft2, so three bundles of shingles are needed per square.

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## 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.

## How Many Rolls Of Felt Will You Need

Roofing felt is sold by the roll. The average roll of 15-pound roofing felt covers about 400 ft2, or 4 squares, while the average roll of 30-pound roofing felt covers about 200 ft2, or 2 squares.

Rolls of felt are 36 wide x 144 long for 15# and 72 long for 30#. Consider other underlayment options as needed, such as rubber or tar products.

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## The Type Of Roof You Want

**The type of roof you want will have a big impact on the cost of your roof replacement.** There are a variety of different types of roofs for you to choose from based on your budget and the look you want.

If youre on a tight budget and looking for an affordable roof, an asphalt shingle roof might be right for you. But if youre looking to upgrade to a longer-lasting and sharp looking roof, theres the standing seam metal roof.

Asphalt and metal are two of the most commonly seen roof types, but there are also premium shingle roofs that come at a premium price. These roofs give you a unique look that really stands out. These premium roofs include cedar shake, slate, and tile.

The premium shingle roofs can get expensive quickly and be more than triple the cost of an asphalt shingle roof.

## What Influences A Roofing Projects Cost

Although a roofs size is always a major factor in calculating project costs, other elements may influence a contractors quote, such as:

- Your location and the average roofing project prices in your area.
- Your choice of roofing material
- Roof accessibility and ease of installation
- The contractors certifications and level of work
- Project timeline

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## Builder Mike Guertin Explains 3 Ways To Calculate The Quantity Of Shingles You’ll Need For Your Next Roofing Job

One of the biggest challenges for experienced builder and novices alike is accurately estimating materials for a construction projectespecially for roofs, because they can be **difficult to access** for taking measurements.

But dont fretIn this excerpt from my book **Roofing with Asphalt Shingles**, I describe three reliable methods for determining the area of a roof, plus Ive included tips for estimating the number of extra shingles youll need for waste, overlaps, and starter shingles.

**Note:** be sure to take your time and double-check your numbers when calculating the quantity of shingles, underlayment, flashings, and other materials needed for your**roofing project**. The more accurate your estimates, the less time youll waste waiting for material deliveries during the project.

## Roof Replacement Vs Repair

**Here are some telling signs that an asphalt shingles roof need to be replaced:**

Many shingles are noticeably buckling or curling- A significant number of shingles is missing Many shingles are missing in the area of the roof valley Numerous shingles have large visible cracks- There is visible shingle discoloration as well as dark streaks on many areas of the roof. Overall, it looks very old and ugly.

**PRO TIP:**

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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 Much Does A Square Of Roofing Cost

The most frequent application for the term square throughout the roofing industry is in regard to pricing and ordering bundles of shingles, so it makes sense to cover the how much a square of roofing costs on average.

In the interest of time, well use the state of Massachusetts as our example. Massachusetts roofers in Boston and the Greater Boston area price their full replacement projects between $5 and $9 per square foot. We can convert *cost per square foot* to *cost per square* by multiplying the original number by 100. So in Boston, Massachusetts and the surrounding suburbs like Framingham or Braintree, the cost of a square of roofing is between $500 and $900.

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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.

## 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.

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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.

## 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.

**Read Also: How To Install Skylights On Low Slope Roof **

## 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.