Avoidable costs – How thinner insulation can help save money on overall construction costs

20 February 2019 Kingspan Insulation UK

Choosing cheaper insulants during housing development is a method often implemented to keep costs down during the construction of new homes.

Despite the initial saving, opting for cheaper methods of insulating, such as using mineral fibre insulation, can increase the overall cost of a new development when compared to the same development that opted for thinner, phenolic insulation, such as Kingspan Kooltherm K106 Cavity Board.

In order to demonstrate this, Kingspan Insulation commissioned Currie & Brown to research the differences in the overall development costs of new houses that used either mineral fibre insulation, or Kingspan Kooltherm K106 Cavity Board.


Through SAP energy performance modelling and U-value calculations, Currie & Brown were able to show that 90 mm of Kingspan Kooltherm K106 Cavity Board within a 100 mm external wall cavity was able to give the same thermal performance as 180 mm of mineral fibre insulation.

Along with the differences in thermal performance, Currie & Brown demonstrated that new houses opting for mineral fibre needed to increase the width of their foundations, in order to accommodate for the increased thickness of the cavity wall and subsequent increase to the external perimeter of the house. Because of this, Currie & Brown found that new large and small detached houses could save £161 and £420 respectively on overall development costs, as the foundation width of the new homes can be reduced from 900 mm to 600 mm to accompany the thinner cavity wall.  

This shows that by opting for the cheaper insulants during construction, developers could incur additional development costs and that by switching to premium performance phenolic insulation, they can save money on the construction overall.