Thermal Conductivity of Isoboard

The Aged Thermal Conductivity (k value) of IsoBoard at 90% Relative Humidity is 0.03 W/m °C. We term this wet
and aged IsoBoard k value the “long term design” value, and this is the value used when performing heat flow calculations for building elements using IsoBoard Insulation. The thermal resistance, or R value, is calculated by dividing the thickness of the IsoBoard selected by the long-term design k-value, to achieve the following table:

Thickness IsoBoard Thickness m Thermal Conductivity Dry 90 Day Aged Thermal Conductivity Dry 5 year aged Aged Thermal Conductivity 90% RH R – Value Dry 90 day aged R – Value 5 year aged R – Value 90% RH
25mm 0.025 0.024 0.028 0.03 1.042 0.893 0.833
30mm 0.03 0.024 0.028 0.03 1.250 1.071 1.000
40mm 0.04 0.024 0.028 0.03 1.667 1.429 1.333
50mm 0.05 0.024 0.028 0.03 2.083 1.786 1.667
80mm 0.08 0.024 0.028 0.03 3.333 2.857 2.667

Fire Performance of IsoBoard

IsoBoard is classified as B/B1/2/H&V in terms of SANS 428. This means that although the board is combustible, it poses no flame spread hazard and can be used in any building type in a horizontal or vertical application, both with and without sprinklers, with the exception of regulated buildings requiring non-combustible materials, such as hotels and hospitals.

Exposed to fire, IsoBoard shrinks away from the heat source. There are no flaming droplets, and no flame spread. The gases released as a product of combustion are less toxic than burning wood.

Isoboard Fire Performance

How does moisture affect thermal insulation?

The biggest factor which detracts from the performance of thermal insulation is moisture. Over time, moisture entering thermal insulation reduces the resistance to heat transfer, reducing the effect of the insulation. As can be seen from the graphic below, IsoBoard XPS is least affected by moisture compared to other common insulators, as it is truly 100% closed cell in construction. IsoBoard XPS retains designed thermal resistance for the life of your building, no matter how wet it gets!

No other typical thermal insulator can make this claim!