How Many Shingles for a 900 Square Foot House?
Roofing squares needed
11.1 squares
A 900 square foot footprint, 36 by 25, at a 6/12 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 length36 ft
- Building width25 ft
- Roof pitch, rise per 12 in6 /12
- Waste allowance10 %
- Ridge length, 0 if unknown36 ft
Roofing squares needed11.1 squares
| Footprint area | 900 sq ft |
|---|---|
| Slope multiplier at 6/12 | 1.12 x |
| Actual roof surface | 1,006 sq ft |
| Squares before waste | 10.1 |
| Squares with 10% waste | 11.1order to this number |
The material list this produces
| Shingles, bundles (3 per square) | 34 |
|---|---|
| Synthetic underlayment, rolls (10 sq each) | 2 |
| Starter strip, linear ft | 144 |
| Ridge cap, linear ft | 36 |
| Drip edge, linear ft | 122 |
| Roofing nails, lb | 24 |
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 | 10.4 squares |
| 6/12 | 11.1 squares |
| 8/12 | 11.9 squares |
| 10/12 | 12.9 squares |
| 12/12 | 14 squares |
What else matters here
Nine hundred square feet of footprint at 6/12 is 1,006 square feet of roof, 11.1 squares with waste, thirty four bundles.
That number assumes a simple gable, and the shape of the roof matters as much as its area. A hip roof over the same footprint at the same pitch has almost exactly the same surface, which surprises people, but it needs considerably more material because every hip is a cut.
On a hip roof, shingles running into a hip are cut on an angle and the offcut is usually unusable, so ten percent waste is not enough. Fifteen is the normal allowance for a hip roof and twenty for a cut up roof with several hips, valleys and dormers. Hips also need cap shingles along every hip as well as the ridge, which on a simple hip roof can easily be two or three times the ridge length.
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 900 sq ft house?
About 34 bundles at a 6/12 pitch with ten percent waste, which is 11.1 squares.
Does a hip roof need more shingles than a gable?
The surface area is nearly identical, but the waste is much higher because every shingle running into a hip is cut on an angle. Allow fifteen percent instead of ten.
How much ridge cap does a hip roof need?
Cap runs along every hip as well as the ridge, so measure all of them. On a simple hip roof that is often two or three times the ridge length alone.
The roofing calculator takes any dimensions you like and hands back the same list.