Hand Cut Roof Calculator UK | Cut Roof Timber & Materials
Work out rafters, ridge, hips, valleys and timber for a traditional hand cut roof. Enter span, pitch and length for instant quantities. Free UK construction calculator.
Results are estimates only and may vary depending on site conditions, material specifications and waste. EasyEstimate and its affiliates accept no responsibility for any loss or damage arising from reliance on these figures. Always verify quantities with your supplier before ordering.
How to Calculate a Hand Cut Roof
A hand cut roof is assembled on site from individual members. To estimate it you need the span, pitch, building length and the roof shape (gable, hip or with valleys), then count each timber component.
Main Components
| Component | Purpose |
|---|---|
| Common rafters | Main sloping members carrying the roof covering |
| Ridge board | Timber the rafters fix to at the apex |
| Purlins | Support rafters mid-span on larger roofs |
| Hip rafters | Run from ridge to corner on a hipped roof |
| Valley rafters | Run where two roof planes meet in an internal angle |
| Ceiling joists / binders | Tie the feet of the rafters and carry the ceiling |
Worked Example: 8m span, 35° pitch, 10m long
- Rafter length = (8 ÷ 2) ÷ cos(35°) = 4 ÷ 0.819 = 4.88m per side (+ overhang)
- Rafters per side at 400mm centres = (10 ÷ 0.4) + 1 = 26, so 52 rafters for both slopes
- Ridge board length = 10m (+ overhang at gable ends)
Use the calculator above to get full timber quantities, covering materials and a waste allowance for your exact roof.
Related Calculators
- Mono Pitch Roof Calculator — single-slope lean-to roofs
- Trussed Roof Calculator — prefabricated truss roof quantities
- Roofing Calculator — tiles, battens and felt for any roof
Frequently Asked Questions
- What is a hand cut roof?
- A hand cut roof (also called a traditional or cut roof) is built on site from individual timbers — rafters, ridge board, purlins, hips, valleys, ceiling joists and binders — cut and assembled by a carpenter, rather than using prefabricated trusses. It is more flexible for complex shapes and conversions.
- What timber sizes are used for a cut roof?
- Rafter sizes depend on span and spacing, but 47×100mm to 47×225mm C16/C24 graded softwood is typical, at 400mm or 600mm centres. Ridge boards are usually 32mm thick, and purlins are sized to the rafter span. Always confirm against span tables or an engineer's design.
- How is a hand cut roof different from trusses?
- Trusses are factory-made triangular frames craned into place quickly. A hand cut roof is built piece by piece on site, giving more freedom for hips, valleys, dormers and room-in-roof designs, but taking longer and needing more skilled labour.
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