How Many Shingles for a 30x40 Pole Barn Roof?
Roofing squares needed
13.9 squares
A 30 by 40 foot pole barn 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 length30 ft
- Building width40 ft
- Roof pitch, rise per 12 in4 /12
- Waste allowance10 %
- Ridge length, 0 if unknown40 ft
Roofing squares needed13.9 squares
| Footprint area | 1,200 sq ft |
|---|---|
| Slope multiplier at 4/12 | 1.05 x |
| Actual roof surface | 1,265 sq ft |
| Squares before waste | 12.6 |
| Squares with 10% waste | 13.9order to this number |
The material list this produces
| Shingles, bundles (3 per square) | 42 |
|---|---|
| Synthetic underlayment, rolls (10 sq each) | 2 |
| Starter strip, linear ft | 156 |
| Ridge cap, linear ft | 40 |
| Drip edge, linear ft | 140 |
| Roofing nails, lb | 31 |
Roof pitch compared
Same house, five pitches.
| Roof pitch | Roofing squares needed |
|---|---|
| 4/12 | 13.9 squares |
| 6/12 | 14.8 squares |
| 8/12 | 15.9 squares |
| 10/12 | 17.2 squares |
| 12/12 | 18.7 squares |
What else matters here
Twelve hundred square feet of barn at 4/12 is 1,265 square feet of roof, just under fourteen squares with waste.
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 30x40 pole barn?
About 42 bundles at a 4/12 pitch with ten percent waste, which is 13.9 squares.
The roofing calculator takes any dimensions you like and hands back the same list.