Avoiding condensation in detached garage/workshop (Climate Zone 5)
Hi GBAers – a while back I asked a broad question re: insulating and air-sealing a detached garage as I convert the building to a hobby woodworking shop. Here’s the link: https://www.greenbuildingadvisor.com/question/air-sealing-and-insulating-detached-garage-with-flat-low-sloping-roof
I got a lot of excellent responses to that question and based my approach on them, along with info from this GBA article: https://www.greenbuildingadvisor.com/article/insulating-low-slope-residential-roofs
Now I am approaching the completion of my project and want to ensure I get the final building envelope details correct (and tightly control costs while doing so). Hopefully someone can point me in a reasonable direction.
This week I had an insulation contractor install a ~1.5″ coat of closed cell spray foam in my 2×4 stud and 2×6 rafter bays. Now I am specifically concerned about preventing/managing condensation in my walls and ceiling, which will be clad in 3/4″ plywood and 7/16 osb respectively. I am in climate zone 5 (Cleveland, OH area).
The workshop will only be used a couple-few hours a day max. My hope is that I will only need to heat and cool the space just enough to control condensation on my large cast iron surfaces and not need to wear gloves while working in the cold months.
I believe my final steps are:
– install mineral wool in my 2×6 rafter bays
– cover ceiling with 7/16 osb
– install fluffy insulation (mineral wool or, preferably from a cost perspective, fiberglass) batts in my walls
– cover walls with 3/4 plywood
– install weather seals around the rollup door, man doors, and windows
My “thin” wall and foam coat lead me to worry that flash and batt in the wall and/or ceiling could backfire. I also wonder if I will actually see appreciable insulating performance beyond what’s delivered by the foam. Should I simply forgo additional insulation in the ceiling and/or walls and simply heat/cool more aggressively when I am actually using the space?
Due to budgetary constraints, for the time being the space is going to be heated with a 110v oil radiator heater, and cooled with a portable AC. I am also considering simply situating 100w work lamps over each of my cast iron surfaces when they’re not in use.
Thanks for any help you folks can provide. A couple pics of the current state of the garage are attached.
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