I like your math… problem with bat is it can get wet without me having a wrap outside of the wood frame. Also I have 0 desire to mess with fiberglass insulation. Also propane is way expensive!
My biggest heat loss right now is in the roof and the back sliding garage door. The roof where it meets the outer walls has pretty big gaps and the back sliding garage door has gaps on both sides of it. Those 2 things will have to be fixed and then it will hold heat in here no problem, at least good enough for the girls I go with.
You can see the cracks in these pictures. I haven’t decided how I will fix the garage door yet…
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