How Many Shingles for a 40x80 Pole Barn Roof?
Roofing squares needed
37.1 squares
A 40 by 80 foot pole barn at a 4/12 pitch with ten percent waste.
When the figures look right, the roofing material list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.
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 length40 ft
- Building width80 ft
- Roof pitch, rise per 12 in4 /12
- Waste allowance10 %
- Ridge length, 0 if unknown80 ft
Roofing squares needed37.1 squares
| Footprint area | 3,200 sq ft |
|---|---|
| Slope multiplier at 4/12 | 1.05 x |
| Actual roof surface | 3,373 sq ft |
| Squares before waste | 33.7 |
| Squares with 10% waste | 37.1order to this number |
The material list this produces
| Shingles, bundles (3 per square) | 112 |
|---|---|
| Synthetic underlayment, rolls (10 sq each) | 4 |
| Starter strip, linear ft | 264 |
| Ridge cap, linear ft | 80 |
| Drip edge, linear ft | 240 |
| Roofing nails, lb | 82 |
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 | 37.1 squares |
| 6/12 | 39.4 squares |
| 8/12 | 42.3 squares |
| 10/12 | 45.8 squares |
| 12/12 | 49.8 squares |
What else matters here
Thirty two hundred square feet of footprint at 4/12 is 3,373 square feet of roof, 37.1 squares with waste, a hundred and twelve bundles.
On a building this size the metal choice splits two ways. Exposed fastener corrugated or ribbed panel is the cheap and common option and holds down through the panel face. Standing seam hides its clips under the seam, so there is no penetration in the field at all, costs a good deal more, and lasts far longer with no screw maintenance.
Two things decide it beyond price. Snow, because a smooth metal roof sheds it all at once, and anything below it, a door, a walkway or a propane tank, needs snow guards or a different plan. And condensation, because bare steel goes below the dew point overnight and drips on whatever is under it. That is handled with a faced insulation blanket in contact with the panel or a factory applied anti condensation membrane, decided before the panels go on rather than after the first cold morning.
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 40x80 pole barn?
About 112 bundles at a 4/12 pitch with ten percent waste, which is 37.1 squares, plus sheathing the roof first.
Is standing seam worth it over corrugated?
It costs considerably more and has no exposed fasteners to maintain, so it lasts much longer. On a long service building it usually pays for itself.
Do I need snow guards on a metal roof?
If snow sliding off would land on a door, a walkway, a tank or a vehicle, yes. A smooth metal roof releases its whole load at once rather than melting away gradually.
The roofing calculator takes any dimensions you like and hands back the same list.