A 25 × 40 ft house with a 4/12 gable roof and 12-in overhangs has about 1,195 sq ft of roof — 12 squares. Order 39 bundles of architectural shingles, including 6% waste.
| Item | Covers | Buy |
|---|---|---|
| Starter strip | 141 ft | 2 bundles |
| Hip & ridge cap | 42 ft | 2 bundles |
| Underlayment | 1,195 sq ft | 2 rolls |
| Ice & water | 168 ft | 3 rolls |
| Drip edge | 141 ft | 15 × 10 ft |
| Nails | 3,859 nails | 1 coil box |
| Ridge vent | 28 ft | 7 × 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 4/12 that is 44 in up the slope → 2 courses of 36-in membrane. Valleys get one 36-in strip centered on the valley line.
Exhaust 480 sq in → 28 ft of ridge vent at 18 sq in per ft. Intake 480 sq in → 53 ft of continuous soffit vent or 9 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 | 39 | $1,755 |
| GAF Timberline HDZ32.8 sq ft per bundle | 39 | $1,755 |
| OC Duration32.8 sq ft per bundle | 39 | $1,632 |
| OC Oakridge32.8 sq ft per bundle | 39 | $1,565 |
| CertainTeed Landmark33.3 sq ft per bundle | 39 | $1,491 |
| IKO Cambridge / Dynasty33.3 sq ft per bundle | 39 | $1,755 |
| Atlas Pinnacle33.3 sq ft per bundle | 39 | $1,755 |
| 3-tab32.3 sq ft per bundle | 40 | $1,720 |
Typical range $5,106–$8,692 · about $5.77 per sq ft of roof
One layer of old architectural shingles ≈ 1.4 tons and 6 cu yd. Book a 15-yard dumpster (about 1.5 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 | 1,169 | 11.7 | 38 | 3 |
| 4/12 | 1.054 | 1,195 | 12 | 39 | 3 |
| 5/12 | 1.083 | 1,229 | 12.3 | 40 | 3 |
| 6/12 | 1.118 | 1,268 | 12.7 | 41 | 3 |
| 7/12 | 1.158 | 1,313 | 13.1 | 43 | 3 |
| 8/12 | 1.202 | 1,363 | 13.6 | 44 | 3 |
| 9/12 | 1.25 | 1,418 | 14.2 | 46 | 3 |
| 10/12 | 1.302 | 1,476 | 14.8 | 48 | 3 |
| 12/12 | 1.414 | 1,604 | 16 | 52 | 3 |
With 12-in overhangs the roof covers 27 × 42 ft = 1,134 sq ft of plan. A 4/12 pitch multiplies that by √(1 + (4/12)²) = 1.0541, giving 1,195.3 sq ft. CertainTeed's waste table puts a 1,195 sq ft gable at 6%, so 1,195.3 × 1.06 ÷ 32.8 sq ft per bundle = 38.63, rounded up to 39 bundles.
As a hip roof the surface is the same, but the edges change: 138 ft of eaves and 78 ft of hips need 2 starter and 4 ridge-cap bundles, and the waste allowance rises from 6% to 13% — 42 bundles instead of 39.
Is 1,000 sq ft your living area rather than the footprint? On a two-story house the footprint is about 500 sq ft, and the same 4/12 roof drops to about 6.3 squares and 21 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) × 1.054 = 44 in up the slope, 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.