VDP with no “mechanical ventilation” in unvented cathedral (no attic) – GreenBuildingAdvisor

Hi All,

I am trying to understand IBC 5.2.9 “Where only air-permeable insulation is installed directly below the structural roof sheathing, air shall be supplied at a flow rate….etc etc.

Does this mean that a VDP is not a code-approved design for an unvented cathedral ceiling with no attic space – as no air or mechanical ventilation can be supplied between something small such as 2×6 rafters with drywall below and roof decking above?

Thanks!

Answer

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