For a 24×24 ft. garage with a gable roof, you will need 24 bundles of shingles. Now, I will explain the process of obtaining this footage and some other tips that will be useful for you.
We have the design of this 24×24 ft. garage, typical gable roof, pitched, the roof overhangs 2 feet on each side of the garage so it is 26 feet long and slopes up 15 feet.
With this model done, it is super easy to get the amount of square footage of the roof and therefore the amount of shingles.
It is only necessary to multiply 15×26 feet (length x height) and we have 390 square feet, as the roof is symmetrical, it has the same amount of footage on the other side therefore it would be:
390 sq ft x2= 780 sq ft of roof area.
How many shingles are needed for a 780 sq. ft. roof?
The number of shingles required for a roof typically depends on the type of shingles you’re planning to use, but most commonly, people use three-tab asphalt shingles for their roofing projects.
A standard three-tab shingle bundle covers about 33.3 square feet. Therefore, to cover a 780-square-foot roof, you would need approximately:
780 square feet / 33.3 square feet per bundle = 23.42 bundles of shingles.
Since you can’t buy a fraction of a bundle, you’d round up and buy 24 bundles of shingles. It’s also a good idea to buy a little extra to account for any waste or errors, so purchasing 25 or 26 bundles may be a good idea.
What additional materials are required for installing shingles?
So, when you’re installing shingles on a roof, it’s not just about the shingles themselves. There are several other materials that you’ll need to complete the project.
One of these is the roofing underlayment, which is also sometimes referred to as tar paper or felt. It’s a water-resistant material that goes directly onto the roof deck, underneath the shingles. Its job is to provide an extra layer of protection against water and wind.
Next, you’re going to need something called drip edge. This is a type of metal flashing that you install at the edges of your roof. The purpose of the drip edge is to direct water away from the fascia and into the gutters.
Speaking of flashing, you’ll also need additional pieces of flashing for any parts of the roof where water could potentially penetrate the shingles, like around chimneys, skylights, or roof valleys. It’s an important material for preventing leaks.
Another crucial component is the roofing nails. They’re specifically designed for roofing projects, with a wide, flat head and a barbed shank that helps them stay in place.
Lastly, you’ll need ridge cap shingles. These are special shingles that are used to cover the peak of the roof, where the two slopes meet. They not only add a finishing touch to the roof but also provide crucial protection against water and wind at these vulnerable points.
And then, of course, there’s the roofing cement. This is used to seal around flashing, vents, and in some cases, it can be used under the shingles themselves to help them stick better and provide additional protection against wind uplift.
How much of these materials will you need for a 24×24 ft. garage roof?
Roofing underlayment: Most commonly used is #15 felt underlayment, which typically comes in rolls covering 432 square feet. For a 780 sq. ft. roof, you would need two rolls.
If you are using #30 felt (a heavier, more protective underlayment), rolls usually cover 216 sq. ft., so you’d need four rolls.
Drip edge: Drip edge typically comes in 10-foot lengths. For a 24×24 foot garage, you’d need at least 96 feet to cover all edges (assuming a simple gable roof), so that’s 10 pieces.
However, it’s a good idea to get some extra in case of cutting errors or damage, so let’s say 11 or 12 pieces.
Flashing: The amount of roof flashing you need depends greatly on the features of your roof. If you have a chimney, skylights, or multiple valleys, you will need more.
For a simple gable roof on a garage without these features, you might not need much beyond the drip edge. Anywhere from 1-3 pieces (again, often sold in 10-foot lengths) might be needed for areas like around the roof vent or any minor features.
Roofing nails: The rule of thumb is that you’ll need approximately 320 nails for every 100 square feet of roofing, for standard three-tab shingles. For a 780 sq. ft. roof, you would need approximately 2,496 nails.
Nails usually come in 1-pound boxes, and there are about 250 nails in a pound. So, you’d need about 10 boxes of nails.
Ridge cap shingles: You would need to measure the linear feet of the ridge to calculate this. On a 24×24 gable roof, the ridge is 24 feet. Ridge cap shingles typically cover about 20 linear feet per bundle, so you would need 2 bundles.
Roofing cement: A single 10.1 oz. tube of roofing cement can provide 30 linear feet of a 1/4″ bead. For a simple roof, a couple of tubes should be sufficient, although having extra on hand isn’t a bad idea.
How do you estimate the amount of waste when shingling a roof?
Estimating the amount of waste for a roofing project is a crucial part of the planning process.
First off, you need to understand that not every shingle you buy will end up on the roof. There will be some cut-offs and breakages during the installation process.
Also, there could be instances where a shingle may get damaged or even simply blown away by the wind during installation.
So, the amount of waste can depend on several factors. For instance, the more complex the roof, the more waste you’re likely to have.
If your roof has a lot of valleys, hips, or angles, there’s going to be a lot more cutting involved. And the more cutting there is, the more waste you generate.
On a simple roof, such as a single or double gable roof, the waste factor is usually around 10%. So, for every 100 square feet of roof, you’re going to generate about 10 square feet of waste.
But on a more complex roof, the waste factor could be 15% or even as much as 20%. It’s one of those things where it’s better to overestimate than underestimate.
The last thing you want is to be in the middle of roofing your house and run out of shingles.
For instance, if you’re dealing with a 780 sq. ft. roof with a simple design, you could plan on about 78 sq. ft. of waste (which is 10% of 780). So you’d want to purchase enough shingles to cover 858 sq. ft. (780 + 78).
If you think the roof is more complex, you might want to estimate a 15% or 20% waste factor instead.