A 30 × 40 ft house with an 8/12 gable roof and 12-in overhangs has about 1,615 sq ft of roof — 16.2 squares. Order 52 bundles of architectural shingles, including 5% waste.
| Item | Covers | Buy |
|---|---|---|
| Starter strip | 161 ft | 2 bundles |
| Hip & ridge cap | 42 ft | 2 bundles |
| Underlayment | 1,615 sq ft | 2 rolls |
| Ice & water | 168 ft | 3 rolls |
| Drip edge | 161 ft | 17 × 10 ft |
| Nails | 5,016 nails | 1 coil box |
| Ridge vent | 32 ft | 8 × 4 ft |
Code runs it from the eave edge to 24 in inside the exterior wall, measured level — counted here from the wall's inside face, as Owens Corning requires. With a 12-in overhang and 6-in wall at 8/12 that is 50 in up the slope → 2 courses of 36-in membrane (8/12 and steeper also need at least 36 in along the slope). Valleys get one 36-in strip centered on the valley line.
Exhaust 576 sq in → 32 ft of ridge vent at 18 sq in per ft. Intake 576 sq in → 64 ft of continuous soffit vent or 11 16×8 vents. Intake should match or beat exhaust; if your attic qualifies for 1/300 (balanced vents, plus a vapor retarder in climate zones 6–8), halve these.
| Line | Bundles | Est. cost |
|---|---|---|
| Architectural32.8 sq ft per bundle | 52 | $2,339 |
| GAF Timberline HDZ32.8 sq ft per bundle | 52 | $2,339 |
| OC Duration32.8 sq ft per bundle | 52 | $2,176 |
| OC Oakridge32.8 sq ft per bundle | 52 | $2,087 |
| CertainTeed Landmark33.3 sq ft per bundle | 51 | $1,950 |
| IKO Cambridge / Dynasty33.3 sq ft per bundle | 51 | $2,294 |
| Atlas Pinnacle33.3 sq ft per bundle | 51 | $2,294 |
| 3-tab32.3 sq ft per bundle | 53 | $2,278 |
Typical range $7,998–$12,843 · about $6.45 per sq ft of roof
One layer of old architectural shingles ≈ 1.9 tons and 8.1 cu yd. Book a 20-yard dumpster (about 2 tons included). Rentals run $395–$875; shingles hit the weight limit long before the bin is full.
Shelf prices from McCoy's (San Marcos, TX) checked Oct 23, 2026; GAF Timberline HDZ, IKO and Atlas shingles use a typical architectural price. Tap any price to use your supplier's.
| Pitch | Multiplier | Roof sq ft | Squares | Bundles | Ice & water rolls |
|---|---|---|---|---|---|
| 3/12 | 1.031 | 1,385 | 13.9 | 45 | 3 |
| 4/12 | 1.054 | 1,417 | 14.2 | 46 | 3 |
| 5/12 | 1.083 | 1,456 | 14.6 | 47 | 3 |
| 6/12 | 1.118 | 1,503 | 15 | 49 | 3 |
| 7/12 | 1.158 | 1,556 | 15.6 | 50 | 3 |
| 8/12 | 1.202 | 1,615 | 16.2 | 52 | 3 |
| 9/12 | 1.25 | 1,680 | 16.8 | 54 | 3 |
| 10/12 | 1.302 | 1,749 | 17.5 | 57 | 3 |
| 12/12 | 1.414 | 1,901 | 19 | 61 | 3 |
With 12-in overhangs the roof covers 32 × 42 ft = 1,344 sq ft of plan. An 8/12 pitch multiplies that by √(1 + (8/12)²) = 1.2019, giving 1,615.3 sq ft. CertainTeed's waste table puts a 1,615 sq ft gable at 5%, so 1,615.3 × 1.05 ÷ 32.8 sq ft per bundle = 51.71, rounded up to 52 bundles.
As a hip roof the surface is the same, but the edges change: 148 ft of eaves and 100 ft of hips need 2 starter and 5 ridge-cap bundles, and the waste allowance rises from 5% to 11% — 55 bundles instead of 52.
Is 1,200 sq ft your living area rather than the footprint? On a two-story house the footprint is about 600 sq ft, and the same 8/12 roof drops to about 8.4 squares and 28 bundles. Always measure the outside of the house, one floor.
Ice & water shield: (12 in of overhang + 6 in of wall + 24 in inside it) × 1.202 = 50 in up the slope (and never less than 36 in at 8/12 or steeper), so 2 courses of 36-in membrane along 84 ft of eaves — 3 rolls of 65 ft after 6-in end laps.
The full method, material data and tips are on the main roofing calculator page.