Reference
Standard Sizes for Roofing Estimates
The units and stock sizes every roofing quantity is counted in, collected in one place.
Units
| Unit | Equals |
|---|---|
| 1 roofing square | 100 sq ft of roof surface (9.29 m²) |
| 1 sq ft | 0.0929 m² |
| 1 ft | 0.3048 m |
| 1 in | 2.54 cm |
| 1 ton (US) | 2,000 lb (907 kg) |
Shingles, rolls and membranes
| Item | Standard size |
|---|---|
| Asphalt shingle bundle | 1/3 square (33.3 sq ft); designer shingles 1/4 or 1/5 |
| Starter strip bundle | 100 to 120 linear ft |
| Hip and ridge cap bundle | 20 to 35 linear ft |
| #15 felt | 36 in × 144 ft (4 squares) |
| #30 felt | 36 in × 72 ft (2 squares) |
| Synthetic underlayment | 48 in × 250 ft (10 squares); 48 in × 100 ft (4 squares) |
| Ice and water membrane | 36 in × 66.7 ft (2 squares); some 75 ft |
| Roll roofing | 36 in × 36 ft (1 square nominal); 19 in selvage rolls for double coverage |
| EPDM | 10 or 20 ft wide × 50 or 100 ft |
| TPO, PVC | 10 or 12 ft wide × 100 ft |
Metal
| Item | Standard size |
|---|---|
| Ribbed panel (PBR, R-panel, 5-rib) | 36 in coverage, cut to length |
| Corrugated sheet | 26 in wide, 24 in coverage; 8, 10, 12 ft and cut lengths |
| Standing seam | 12, 16 or 18 in seam spacing, cut to length |
| Trim (ridge, eave, rake, valley) | 10 ft sticks; some 12 ft |
| Drip edge | 10 ft sticks, 2 in minimum lap |
| Valley metal | 24 in wide minimum for open valleys, 10 ft sticks |
| Step flashing | 4 × 4 × 8 in; 5 × 5 × 10 in |
Tile, slate, cedar
| Item | Standard size |
|---|---|
| Concrete flat or S-tile | about 13 × 17 in; 86 to 95 per square |
| Two-piece clay barrel | 150 to 180 pieces per square |
| Slate | 10 to 24 in long; 18 × 10 in common; half the length is a common width |
| Cedar shingles | 16, 18, 24 in long; 4 bundles per square at 5, 5½, 7½ in |
| Cedar shakes | 18, 24 in long; 5 bundles per square at 7½, 10 in |
| Battens | 1×2 or 1×3 treated, 8 to 16 ft |
Framing, ladders, skylights
| Item | Standard size |
|---|---|
| Rafter or truss spacing | 16 or 24 in on centre (400 or 600 mm) |
| Ridge board | 1½ in (2× lumber), 1¾ in LVL |
| Lumber lengths | 8 to 24 ft in 2 ft steps |
| Plywood or OSB sheathing | 4 × 8 ft (32 sq ft) |
| Extension ladders | 16, 20, 24, 28, 32, 36, 40 ft (reach about 3 to 5 ft less) |
| Skylights (nominal) | 14, 21, 30, 44 in wide × 27 to 54 in long |
Gutters and disposal
| Item | Standard size |
|---|---|
| K-style gutter | 5 or 6 in; 10 ft sections or seamless |
| Half-round gutter | 5 or 6 in |
| Downspout | 2 × 3, 3 × 4 in rectangular; 3, 4 in round; 10 ft lengths |
| Roll-off dumpster | 10, 15, 20, 30, 40 cubic yards, with a tonnage allowance |
Sources
Manufacturers’ product data for each item; ASTM D226 for felt; IRC R905.2.8 for flashing minimums; ANSI A14 overlap rules for extension ladders; haulers’ published container sizes. Sizes vary by brand and region; the product label governs.
Calculators that use these sizes
The drip edge calculator, the metal roof trim calculator, the synthetic slate calculator, the ladder length calculator, the skylight size calculator, the gutter length calculator and the tear-off dumpster calculator all count in these units.