Should a Vapor Barrier be installed over Exterior Grade Plywood?

Michael Klauck
Updated: Sept. 9, 2020

I have a 40 year old cottage in the Kawarthas.  It has exterior grade Plywood.  The walls are insulated with traditional Fiberglass Pink.  I will be putting solid 3/4" wood siding over top of the exterior walls.  I plan on strapping the cottage with 1" x 2" and filling the gaps with 1" of Rigid Foam insulation.  In the future I may add A/C to the cottage.  Do you believe a Vapor Barrier to be necessary?  Thank-you Michael

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