Does changing R-value affect hygrothermal properties?

PallaviMantha · Post by **PallaviMantha** » Fri Jun 03, 2011 4:04 am -1100

Hello,

I want to change the R value/inch of the Closed cell spray foam insulation (database has R-value of 5.95) to R-6.5/inch. Will the change in R-value affect the hygrothermal functions of the material?

or should I just adjust the thickness of my material until I achieve the R-value I desire?

I appreciate your help,
Thanks,
Pallavi

Amandine Piot · Post by **Amandine Piot** » Mon Jun 06, 2011 12:24 am -1100

Hello,

you can change the thermal conductivity of the material (double click on the material, then click on the "unlock" button), this will not change the other properties of the material (for example sorption curve or water vapor transmission).
You must be carefull that for this material there exist a dependency of the thermal conductivity on the temperature : if you ajdust the value at 10°C, be sure that the value for higher temperatures remains equal or higher.

For a realistic approach the thickness of the wall should be the same as the one of the "real" wall you are studying. Changing the thickness of the insulation will change the total vapour resistance of your wall for example.

PallaviMantha · Post by **PallaviMantha** » Wed Jul 06, 2011 9:53 am -1100

Thank you, Amandine!