A table of typical k-values appears below for two common Fletcher Insulation products used in HVAC (Heating, Ventilation and Air Conditioning) and light industrial applications.

Surface temperatures may be used for Operating and/or Ambient temperatures providing the appropriate selection is made for the surface condition in the drop down menus.

In cases where the operating temperature is a fluid that will contact the inside surface, it should be assumed that the internal surface temperature is equal to the operating temperature and the appropriate selection made in the drop down menu.


Mean Temperature* (˚C) Thermal Conductivity (W/mK)
FI32 Semi-Rigid FI48 Rigid Board
20 0.032 0.031
50 0.038 0.035
100 0.050 0.045
150 0.063 0.053
200 0.080 0.065
250 0.080

* The mean temperature is the average of the internal and external surface temperatures.

Desired Surface Temperature  degrees C
Inside Operating Temperature  degrees C
Inside Surface Condition
Ambient Temperature  degrees C
Outside Surface Condition
Insulation k Value  W/mK
Insulation Thickness  mm

Note: Tools and Calculators are designed to provide indicative figures only. For more accurate data specific to your construction, contact Fletcher Insulation Technical Services prior to commencing a project.