About 60 bundles if 1,800 square feet is the roof surface, at three bundles per square with 10% waste. If it is the footprint of the house and the roof is a 6/12 pitch, the roof is 2,012 square feet and it takes about 67 bundles.
How many bundles of shingles you need for 1,800 square feet depends entirely on whether that figure is the roof surface or the floor area of the house, and most people mean the house. If 1,800 square feet is the roof itself, it takes about 60 bundles at three per square with 10% waste. If it is the footprint and the roof is a standard 6/12 pitch, the roof surface is larger — about 2,012 square feet — and it takes about 67 bundles. The tables below give both, at every common pitch.
This is what decides the answer, and most people mean the house. A roof is always larger than the footprint under it, because it is sloped — by 5% at 3/12 and by 41% at 12/12. Ordering against the footprint is the single most common reason a shingle order comes up short.
| If 1,800 sq ft is… | Roof area | Squares +10% | Bundles at 3/square |
|---|---|---|---|
| The roof surface itself | 1,800 sq ft | 19.8 | 60 |
| The footprint, roof at 3/12 | 1,855 sq ft | 20.4 | 62 |
| The footprint, roof at 4/12 | 1,897 sq ft | 20.9 | 63 |
| The footprint, roof at 6/12 | 2,012 sq ft | 22.1 | 67 |
| The footprint, roof at 8/12 | 2,163 sq ft | 23.8 | 72 |
| The footprint, roof at 10/12 | 2,343 sq ft | 25.8 | 78 |
| The footprint, roof at 12/12 | 2,546 sq ft | 28 | 85 |
Three bundles per square, 10% waste for a simple gable. A hip roof runs 15% and a cut-up roof with several valleys up to 20%.
| Waste | Suits | Squares | Bundles |
|---|---|---|---|
| 10% | Simple gable, no valleys | 19.8 | 60 |
| 15% | Hip roof | 20.7 | 63 |
| 20% | Cut-up roof, several valleys | 21.6 | 65 |
About 60 bundles if 1,800 square feet is the roof surface, at three bundles per square with 10% waste. If it is the footprint of the house and the roof is a 6/12 pitch, the roof is about 2,012 square feet and it takes about 67 bundles.
18 squares before waste, since a roofing square is exactly 100 square feet of finished roof. With 10% waste added you would order against 19.8 squares.
Only if you are working from the footprint. Pitch does not change the bundles per square — it changes how many square feet of roof sit above a given footprint, which is 5% more at 3/12 and 41% more at 12/12.
Slightly. Unopened bundles usually go back for credit, but a second delivery for three bundles costs a trip charge and stops the crew for half a day — and on a stripped roof that is a weather risk as well as a cost.