Roofing Timber Design

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:

For metal sheeting (IBR, Chromadek etc) use the following tables:

Manufacturing a truss on-site? – use these tables for basic top chord and bottom chord sizes.