How Many Shingles for a 24x30 Garage Roof?
Roofing squares needed
8.3 squares
A 24 by 30 foot garage at a 4/12 pitch with ten percent waste.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Building length24 ft
- Building width30 ft
- Roof pitch, rise per 12 in4 /12
- Waste allowance10 %
- Ridge length, 0 if unknown30 ft
Roofing squares needed8.3 squares
| Footprint area | 720 sq ft |
|---|---|
| Slope multiplier at 4/12 | 1.05 x |
| Actual roof surface | 759 sq ft |
| Squares before waste | 7.6 |
| Squares with 10% waste | 8.3order to this number |
The material list this produces
| Shingles, bundles (3 per square) | 26 |
|---|---|
| Synthetic underlayment, rolls (10 sq each) | 1 |
| Starter strip, linear ft | 120 |
| Ridge cap, linear ft | 30 |
| Drip edge, linear ft | 108 |
| Roofing nails, lb | 18 |
Roof pitch compared
Pitch is the number most people guess at, and it is worth more shingles than any other input. Same house, five pitches.
| Roof pitch | Roofing squares needed |
|---|---|
| 4/12 | 8.3 squares |
| 6/12 | 8.9 squares |
| 8/12 | 9.5 squares |
| 10/12 | 10.3 squares |
| 12/12 | 11.2 squares |
What else matters here
Seven hundred and twenty square feet of footprint at 4/12 is 759 square feet of roof, 8.3 squares with waste, twenty six bundles.
The material list includes 108 linear feet of drip edge, which is the perimeter, and that metal is what the gutter hangs behind. Drip edge at the eave goes on first, directly on the deck and under the underlayment, so anything that gets past the shingles runs out over the metal. At the rake it goes on last, over the underlayment, so wind driven water cannot get behind it.
The point of the eave piece is to throw water clear of the fascia and into the gutter rather than letting it run back along the underside of the sheathing. If the gutter sits too low or too far out, water sheets past it in heavy rain no matter how good the roof is. Size the gutter and the downspouts to the roof area: a five inch K style gutter with a downspout every thirty five or forty feet handles a roof this size in most of the country, and more downspouts beats a bigger gutter.
What this calculator assumes
- Footprint times the slope multiplier gives the actual roof surface. A 6/12 roof is 11.8 percent larger than the ground it covers, which is the number most people forget.
- Three bundles per square is standard for both three tab and architectural shingles. Check your brand, a few premium lines run four.
- Synthetic underlayment is figured at 10 squares per roll, starter and ridge cap at one linear foot per foot.
Questions people ask
How many bundles of shingles for a 24x30 garage?
About 26 bundles at a 4/12 pitch with ten percent waste, which is 8.3 squares.
Does drip edge go over or under the underlayment?
Under it at the eave and over it at the rake. That order sends water out over the metal at the bottom and keeps wind driven rain from getting behind it at the sides.
How many downspouts does a garage roof need?
One every thirty five to forty feet of gutter is a reasonable rule. Adding downspouts helps more than going to a larger gutter.
The roofing calculator takes any dimensions you like and hands back the same list.