Shingles for a 40 × 46 ft roof at 6/12, simple gable
| Bundles3 per square | 68bundles |
|---|---|
| Squares (with waste) | 22.6sq |
| Roof area1,840 ft² footprint × 1.118 pitch factor | 2,057ft² |
| Pitch factor√(1 + (6/12)²) — pure geometry | 1.118 |
| Waste allowancetwo planes, cuts only at the rakes | 10% |
| Starter shingles172 ft of eave and rake | 2bundles |
| Hip & ridge cap46 ft of ridge | 3bundles |
| Underlaymentsynthetic, 10 squares per roll | 3rolls |
| Ice & water shieldeaves, 24″ inside the exterior wall line — check if your code requires it | 577ft² |
| Roofing nails — standard4 per shingle, about 7,241 nails | 52lb |
| Roofing nails — high wind6 per shingle — required in high-wind zones and by most warranties above 110 mph | 78lb |
| Walkable6/12 can normally be walked | Yes, with care |
Notes
- Footprint is not roof area, and the gap is bigger than people expect. A 40 × 46 ft footprint is 1,840 ft² on the ground but 2,057 ft² of roof at 6/12. Ordering off the footprint leaves you 2.2 squares short — and that is before waste.
- The pitch factor is √(1 + (rise/12)²). There is no estimate in it and no manufacturer fudge — it is the hypotenuse. 6/12 gives 1.118.
- 10% waste for a simple gable roof: two planes, cuts only at the rakes. A simple gable wastes least because the only cuts are at the rakes; every hip and valley adds a run of angled cuts that produce offcuts nothing else uses.
- Starter and cap are separate purchases, and they are the two lines that get left off estimates. 2 bundles of starter for 172 ft of eave and rake, 3 bundles of hip and ridge for 46 ft. Using field shingles as starter voids most manufacturer wind warranties.
- At 6/12 the roof is walkable with proper footwear and a harness. Steeper than 8/12 and you are into staging.
- Tear-off is the other half of the job. A single layer of asphalt shingle weighs 200–350 lb per square, so this roof carries about 6,223 lb of old material to remove and skip.
Footprint is not roof area
This is where roofing estimates go wrong, and they go wrong in the direction that leaves you short on a Saturday.
A 40 × 46 ft footprint is 1,840 ft² on the ground. At 6/12 the roof over it is 2,057 ft² — the pitch factor is 1.118, which is √(1 + (6/12)²). Pure geometry, no fudge factor.
Order off the footprint and you are 2.2 squares short before waste is even counted.
Squares and bundles
22.6 squares with 10% waste for a simple gable roof — 68 bundles at three per square.
Waste is not one number. A simple gable cuts only at the rakes. A hip roof cuts along every hip. A cut-up roof with valleys and dormers throws away a fifth of what you buy, and no amount of careful planning changes that.
The two lines everyone forgets
Starter: 2 bundles for 172 ft of eave and rake. Hip and ridge cap: 3 bundles for 46 ft.
These are separate products, not field shingles cut down. Using field shingles as starter voids most manufacturers' wind warranties, which is discovered at the claim rather than at the purchase.
Underneath
3 rolls of synthetic underlayment, and 577 ft² of ice-and-water shield at the eaves — 24 inches inside the exterior wall line, which is what the IRC asks for where it applies. Check whether your jurisdiction requires it.
52 lb of roofing nails at four per shingle, or lb at six for a high-wind zone.
Two things to price before you decide it is DIY
Tear-off: about 6,223 lb of old shingle to strip and skip.
And access. Above 8/12 a roof stops being walkable for most people, and roof jacks, planks or scaffolding cost real money that belongs in the estimate before you decide this is a DIY job.
Nearby sizes
- Shingles for a 38 × 46 ft roof at 6/12, simple gable
- Shingles for a 42 × 46 ft roof at 6/12, simple gable
- Shingles for a 36 × 46 ft roof at 6/12, simple gable
- Shingles for a 44 × 46 ft roof at 6/12, simple gable
- Shingles for a 40 × 44 ft roof at 6/12, simple gable
- Shingles for a 40 × 48 ft roof at 6/12, simple gable
- Shingles for a 40 × 42 ft roof at 6/12, simple gable
- Shingles for a 40 × 50 ft roof at 6/12, simple gable
- Shingles for a 40 × 46 ft roof at 5/12, simple gable
- Shingles for a 40 × 46 ft roof at 8/12, simple gable
- Shingles for a 40 × 46 ft roof at 4/12, simple gable
- Shingles for a 40 × 46 ft roof at 10/12, simple gable
Read more
- Garage Roof Replacement Cost: $1,200–$4,500 With Shingles, and How to Price a Shed RoofSmall roofs cost more per square foot than house roofs because the trip, setup and disposal are spread over fewer squares. The roof area, not the garage's floor size, decides the price.
- Mobile Home Roof Replacement Cost: $4,000–$7,000 for Most Homes, by Width and MaterialMobile home roofs cost less per square foot than site-built roofs because they are low, single-story and simple. Width and material decide most of the price.
- Cost to Fix a Roof Leak: About $800 on Average, $100 to $3,500 Depending on Where It StartsThe price of a leak repair depends on where the water gets in. A clogged gutter or cracked vent boot costs a few hundred dollars; a valley or chimney can cost several times that.
- Tile Roof Replacement Cost: Clay, Concrete, Slate and Cedar Shake, and Why the Underlayment Is Often the Real JobClay tile and slate often outlast the underlayment beneath them. That is why many "tile roof replacements" reuse the tiles and replace only what is underneath, at a fraction of the price of a new roof.