Creating a conditioned storage room in the vented garage attic?
So I live in Dallas, TX. Have a 1990 large home, with a very large walking attic space over the garage, easily 700 sq ft, with vaulted roof extending at least another 20 feet tall in the center. The attic has 2 x 10 at 16 center ceiling joist over the garage, extending up to 20 feet long, supported at 10 feet intervals by perpendicular support 2 x 10s. I had a structural engineer indicate that weight bearing in the space would exceed 1000 lbs easily, without leading to ceiling sag in the garage. The attic contains in a separate section two water heaters and the family room/master bedroom AC/Furnace.
I actually have a gentleman coming next week to lay down plywood sheets to floor the attic, as well as install a Versa Attic Lift, so as to use the space for storage.
Here is my question. My wife wants a conditioned storage room in the attic for delicate items that will not easily survive the Texas heat in the attic. I intend to lay down fiberglass batts over the garage ceiling to decrease the heat from the garage below, have the contractor put down the flooring, build a small 10 x 10 room in the attic, seal the cracks, spray foam the exterior, run lights, weather seal the door, and have the AC guys run a small vent/return off the main unit.
Do not intend to make it a livable space, just a conditioned storage unit.
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