A 12×16 ft gable roof at 4/12 with 6-in overhangs needs 12 panels of 36-in coverage (6 per side), each 6' 11" long, plus about 187 screws.
| Item | Length | Buy |
|---|---|---|
| Ridge cap | 17 ft | 2 × 10½ ft |
| Eave trim | 34 ft | 4 × 10½ ft |
| Rake trim | 28 ft | 3 × 10½ ft |
| Inside closures (eave) | 34 ft | 12 × 36 in |
| Outside closures (ridge) | 34 ft | 12 × 36 in |
| Profile | Panels | Lin ft | Panel cost |
|---|---|---|---|
| 36-in rib panel36-in coverage | 12 | 83 | $336 |
| 5V crimp24-in coverage | 18 | 125 | $423 |
29 ga Galvalume prices from McCoy's (San Marcos, TX), Oct 23, 2026; cut-to-length uses the same per-foot rate. Eave and rake trim vary by supplier — get a quote with the panels.
| Pitch | Panel length | Panels | Roof sq ft | Screws | Panel cost |
|---|---|---|---|---|---|
| 3/12 | 6' 9" | 12 | 228 | 183 | $336 |
| 4/12 | 6' 11" | 12 | 233 | 187 | $336 |
| 5/12 | 7' 1" | 12 | 239 | 192 | $366 |
| 6/12 | 7' 4" | 12 | 247 | 198 | $366 |
| 8/12 | 7' 10" | 12 | 266 | 213 | $366 |
Roof area: 17 × 13 ft of plan × 1.054 = 233 sq ft (2.3 squares). At Fabral's 80 screws per square that's 187 panel screws — #14 × 1 in Woodtite into a plywood or OSB deck, #10 × 1½ in into purlins — before trim and stitch screws.
Under 3/12 the IRC requires lap sealant on exposed-fastener panels; 36-in rib panels are rated down to 2½/12 by their makers and 5V crimp to 3/12. At 4/12 either profile is fine without sealant.
The full method, material data and tips are on the main metal roofing calculator page.