The Lean To Truss Estimating Calculator is used to calculate the Labour, Materials and Plant content and costs of prefabricated lean to truss roofs.

The Lean To Truss Roof Estimating Calculator calculates the following items:

  • Roof trusses and bracing
  • Fascias and guttering
  • Tiling, sarking, felt undercloak and leadwork
  • Plastering and insulation
  • Internal and external decorating
  • Leadwork at the intersection of the walls and roof.
  • Plus all labour associated with the above

All of the items required for a lean to roof are specified from the Specification.


  • Please pay particular attention to the Usage Factor for the roof tiling, which is highly variable for both labour and material and are particularly dependant on the roof tile selected. To modify Usage Factors, please see the topics Edit Usage Factor & Build Phase of a Resource or Edit a Resource in a Worksheet .
  • In addition, you should pay attention to the costs of the roof trusses, since their costs vary depending on the pitch and span.
  • The Lean to Truss Roof Estimating Calculator can be used in conjunction with other roof types to create more complex roofs. Alternatively, you can use the Universal Truss Roof Estimating Calculator to estimate complex roofs which cannot easily be broken down into their constituent parts.