The Gas Flue System Estimating Calculator is based on the Composite Estimating Calculator and is a collection of items of labour, material and plant required to fit out a gas flue system. You should review each item to see whether they are required, and to check that the quantities and prices are adequate.

The Gas Flue System Estimating Calculator calculates the following items:

  • Starter block and fire back
  • Flue blocks
  • Termination block
  • Flue sealant
  • Plus all labour associated with the above

This Estimating Calculator is NOT linked to the Specification.


  • You should pay particular attention to the termination of the flue. You should consider carefully the type of extension to the flue system to the outside vent. Plumbers or roofing contractors or specialist fitters often carry out this item.