About this calculator
Count roof sheets such as corrugated (Custom Orb), Trimdek or Klip-Lok in Colorbond or Zincalume, with ridge and barge capping, roof blanket, foam closures and screws.
How it’s calculated
Panels per side = ceil(eaves length ÷ coverage width). Panel length = slope length + eaves projection. Screws are estimated at about 7 per m².
Worked example
With these inputs:
- Roof length along eaves
- 12 m
- Slope length (eaves to ridge)
- 4.5 m
- Roof sides
- Two (gable)
- Panel coverage width
- 762 mm
- Extra length at eaves
- 50 mm
the result is:
- Roof sheets needed
- 32 sheets
- Panels per side
- 16
- Sheet area
- 110.95 m²
Tips from the trade
- Use the panel’s coverage width, not its overall width. Side laps eat 2–4 inches or 50–100 mm.
- Order panels cut to length. Long panels may need an end lap; check the maker’s minimum overlap for your pitch.
- Fix through the high rib or the flat depending on the profile, following the manufacturer.
- Minimum pitch depends on the profile: 5° for corrugated, 2° for Trimdek and 1° for Klip-Lok. In NCC climate zones 6, 7 and 8 the roof space also needs ventilation (see the roof ventilation calculator).
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the NCC and Australian Standards before ordering.