: The overlay typically provides a permeance level of 12–16 perms , allowing the panels to "breathe" and dry out.
The 1.5-inch variant is often the minimum thickness required in the ZIP-R product line to satisfy energy codes in colder climates. However, designers must account for specific regional requirements: Roxul Comfortboard - disadvantages? - GreenBuildingAdvisor 1.5.zip
The 1.5-inch panel is a composite material consisting of three primary layers: : The overlay typically provides a permeance level
: In Climate Zone 5, the R-6.6 provided by the 1.5-inch panel is sufficient to keep the sheathing boundary above the dew point, preventing internal condensation when using fiber insulation in the stud cavity. 4. Application and Code Compliance 1.5.zip
, significantly lower than standard OSB and housewrap combinations ( 3. Advantages in Construction