How do I insulate an unvented roof with a T&G ceiling? Also: question on wall detail
I have read many of the articles on low slope unvented roofs and still am unclear. I need to know if both those plans work and if not, what is the solution. I am in CZ6 Utah cold winter below zero and hot summer up to 95 degrees and very dry. 1/12 pitch roof, monopitch south to north, south being the taller side. Passive solar design with south windows,
Plan from exterior to interior:
Option 1. Sika Sarnafil membrane, 4″ fiberglass face Polyiso (the brown covered stuff), 5/8″ sheathing of OSB or Plywood, 1″ Closed cell spray on underside of sheathing as air barrier, rest of 12″ TJI cavity filled with cellulose, Polyester netting, Tongue and groove wood.
Option 2. Sika Sarnafil membrane, 4″ fiberglass face Polyiso (the brown covered stuff), 5/8″ sheathing of OSB or Plywood, 12″ TJI cavity filled with cellulose, CertainTeed Membrain as netting and air barrier, Tongue and groove wood.
(Basically thes same as option 1, but with certainteed Membrain just above T&G instead of the 1″ Closed cell spray foam underneath sheathing deck.)
As for my wood frame above grade walls, does it matter if I use 2″ of paper faced polyiso or 2″ foil faced polyiso on the exterior?
Here is the plan from the exterior to interior: Swisspearl cement board open rainscreen cladding, Vaproshield Revealshield Weather barrier, 3/4″ battens for rainscreen airgap, 2″ polyiso (paper faced or foil faced?), 7/16″ OSB or plywood, 2×6 wall with cellulose (densepack or blown?), drywall and paint.
Thanks very much for any help on this, as I want to get this right in my very cold winter and hot summer climate.
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