The R-value of FireCrunch is a measure of its thermal resistance. The higher the numbers the better the insulator.
R-value is measured as m2/K/w
The values for FireCrunch are:
10mm FireCrunch = 0.066 m2K/w
19mm FireCrunch = 0.132 m2K/w
So the 10mm board has an R Value of 0.066
To work out the approximate R-value for a wall with a layer of 10mm FireCrunch each side of the stud with a R2.5 batt between them –
10mm FireCrunch + Batt + 10mm FireCrunch = Wall R-value therefore 0.066 + 2.5 + 0.066 = 2.632 (So the approximate R-value for the wall would be 2.6)
Please note that the above is just an approximate guide. Actual figures would have to be calculated. There are a number of on line calculators that can do this for you.