Roofing Timber Design
It is vital that the correct structural timber is used for your roof. While the guidelines and graphs below provide basic information on the correct installation of certain timber types, Somerset Timbers recommend that you:
- Read How To Use Graphs
- Consult with a structural engineer assists in the design of timber structures.
- Consult with your roof sheeting supplier to determine the correct purlin spacing, which is determined by factors like the weight of the ceiling, beams, insulation, windows; wind loading, and roof pitch.
For concrete tiles and fibre cement roof sheeting use the following tables:
- Roof Concrete Tiles-38-50mm
- Roof-Concrete Tiles-76mm
- Roof Concrete Tiles Laminated-32-45mm
- Roof Concrete Tiles Laminated-70-100mm
For metal sheeting (IBR, Chromadek etc) use the following tables:
- Roof Metal Sheeting-38-50mm
- Roof Metal Sheeting-76mm
- Roof Metal Sheeting Laminated-32-45mm
- Roof Metal Sheeting Laminated-70-100mm
Manufacturing a truss on-site? – use these tables for basic top chord and bottom chord sizes.