Hello,
I want to put some insulation in my garage. I live north of SF, and the garage is already getting warm during the day. The exterior walls are 1/4″ ply, with batten boards, backed with felt paper, which is what I see exposed in the Garage. My plan was to insulate, and put up drywall.
Which way should I face the foil? or should I go without foil? Is it worth replacing the 1/4″ exterior ply with something more significant? Or should I put up 1/2″ or 3/4″ ply on the interior.
Any help appreciated. When I insulate the roof, what should I do for vents? It’s an exposed truss system with CDX roof and composite shingles.
thanks.
cykeler.
Replies
It being a garage, less worry about vapor transfer.
I assume you are using FG with foil vapor barrier and the garage is unheated. Since more vapor transfer would likely occur from the outside in, face the foil out.
You can go with an unvented roof (assuming your local building code will permit that). It may void some shingle manufacturer's warranties and may make the garage a bit hotter inside.
For fire protection, you may be better off installing gable vents (or go with soffet and ridge vents if you feel ambitious), insulate between the truss bottom chords, and use type X GWB at least 5/8" on the ceiling and walls.
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