Retrofit insulation in cathedral ceiling with truss-joist.
I am looking for feedback and recommendations regarding retro-fitting insulation in the roof of an existing home with a cathedral ceiling.
Parameters of existing conditions:
– gable/pitched roof (9:12 on one side, 4:12 on other)
– roof framed with 18″ deep parallel chord truss, 24″ O/C
– Interior to exterior assembly: drywall, 1×3 strapping across truss, poly vapor barrier, 9-1/4″ fiberglass insulation, vent space, plywood roof sheathing, steel roofing.
– Climate zone 5, near Kingston, ON, Canada
At this point, my idea is to:
1)remove the steel and whatever underlayment
2) dense-pack the remaining space with cellulose on top of the fiberglass through holes cut from the exterior
3) apply a vapor-open air barrier on top of existing sheathing (Intello x??? or other recommendations, please!?!?)
4) apply 2×3 on the flat, on top of each truss, for vent space
5) apply new plywood roof sheathing
6) New underlayment (conventional vapor impermeable? or Solitex mento, if there is a compelling reason?) and steel roofing directly on top of new sheathing.
Can anyone point out the pitfalls of this approach or suggest improvements?
Thank you so much!!!
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