Roxul ComfortBoard IS - Manual (Page 26)

ROXUL
® The Better Insulation™ 24
A Class III vapor control layer may be used instead of a Class I or II layer on the interior of framed walls in
zone 4c and higher, if any of the following criteria are met:
Zone 4c (e.g., Vancouver, Seattle or Portland)
 Sheathing-to-cavity R-value ratio of >0.20
 Insulated sheathing with an R-value ≥ 2.5 on a 2x4 framed wall
 Insulated sheathing with an R-value ≥ 3.75 on a 2x6 framed wall.
Zone 5 (e.g. Chicago, Windsor, Boston)
 Sheathing-to-cavity R-value ratio of >0.35
 Insulated sheathing with an R-value ≥ 5 (e.g., 1.25” ROXUL COMFORTBOARD IS) on a 2x4
framed wall
 Insulated sheathing with an R-value ≥ 7.5 (e.g., 2” ROXUL COMFORTBOARD IS) on a 2x6 framed
wall.
Zone 6 (e.g., Toronto, Ottawa, Helena, Montreal, Halifax, Minneapolis)
 Sheathing-to-cavity R-value ratio of >0.50
 Insulated sheathing with an R-value ≥ 7.5 (e.g., 2” ROXUL COMFORTBAORD IS) on a 2x4 framed
wall
 Insulated sheathing with an R-value ≥ 11.25 (e.g., 3” ROXUL COMFORTBOARD IS) on a 2x6
framed wall.
Zones 7 and 8 (e.g. Calgary, Edmonton, Whitehorse, Anchorage, Fair- banks)
 Sheathing-to-cavity R-value ratio of >0.70
 Insulated sheathing with an R-value ≥ 10 (e.g., 2.5” ROXUL COMFORTBAORD IS) on a 2x4
framed wall
 Insulated sheathing with an R-value ≥ 15 (e.g., 3.75” ROXUL COMFORTBOARD IS) on a 2x6
framed wall.