R-VALUE

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R-VALUE

 

The Thermal Conductivity (k value) of new IsoBoard is 0.024W/m°C, and that of 5-year aged IsoBoard at 90% relative humidity is 0.03W/m°C, which is referred to as the “long term design” value. The Thermal Resistance (r value) of IsoBoard is calculated by dividing the thickness of the IsoBoard by the Thermal Conductivity (k-value), to achieve the table below.
For SANS10400XA r-value calculations the k-value of new IsoBoard of 0.024W/m°C can be used, but IsoBoard recommend that the “long term design” value be used when doing a Rational Design.  Because IsoBoard is expected to last for the life of the building, using an aged value allows a confident prediction that required thermal performance standards will continue to be met.

Thickness IsoBoard
 

25mm

30mm

40mm

50mm

60mm

70mm

80mm

Thickness m
 
 

0.025

0.03

0.04

0.05

0.06

0.07

0.08

THERMAL CONDUCTIVITY DRY 90 DAY AGED

0.024

0.024

0.024

0.024

0.024

0.024

0.024

THERMAL CONDUCTIVITY DRY 5 YEAR AGED

0.028

0.028

0.028

0.028

0.028

0.028

0.028

THERMAL CONDUCTIVITY 90% RH

0.03

0.03

0.03

0.03

0.03

0.03

0.03

R – VALUE DRY 90 DAY AGED
 

1.042

1.250

1.667

2.083

2.5

2.92

3.333

R – VALUE 5 YEAR AGED
 

0.893

1.071

1.429

1.786

2.14

2.50

2.857

R – VALUE 90% RH
 
 

0.833

1.000

1.333

1.667

2.0

2.33

2.667

R-Value-page-square Use these values for SANS 10400XA R-value calculations