My wife got a wonderful opportunity (new job) but it meant a dismantling of the old workshop, move to Chicago-land and now finally a rebuilding of the former workshop in the 2 car detached garage a couple years after we did the move. Basic 2 car garage, roughly 24 x 24 with a 7.5' clear height(challenge) but does have an attached Florida Room/3 season sunroom that works well for storage of some of the less frequently used items. Most walls are insulated(and already working to fix the ones that aren't) but I'm struggling with the best option for the ceiling so I can keep a reasonable temp in there and be able to continue work this winter. Key requirement is that it must be mounted close to the underside roof deck/rafters as I don't have the headroom space to loose any more height mounting to the bottom of the tie beams. I could possibly deck the top side of the tie beams and then use blown in or bats over that deck.
What I've considered so far:
- Conventional fiberglass batt: Concerned that needs to be covered with drywall for fire protection and not excited about doing that, not difficult just never enjoyed hanging rock on ceilings
- Mineral wool/Roxul: no experience with it in an application like this but I like the product and have used in walls, rafters are on 24" centers which makes it more time consuming to put up as I've only ever seen it for 16" OC widths
- Spray foam: Benefits of insulation and vapor barrier, but mixed opinions on if it should be sprayed directly to the bottom of the roof deck. Brand new roof on the garage and would hate to cook my new shingles. Also not looking forward to having to get everything out of the space to do this well
- Rigid foam: Thinking of something like linked below as opposed to the normal polystyrene pink or blue foam board, bit cheaper and looks like it would be better for an exposed application and not require being covered by drywall
https://www.homedepot.com/p/R-Tech-2-in-x-4-ft-x-8-ft-R-7-7-Rigid-Foam-Insulation-310891/202532856
I'm kinda leaning towards the mineral wool/Roxul option with a separate, opaque white plastic vapor barrier or the rigid foam board..what does the group think? Any options I'm missing or thoughts or experience with a similar application? I'm not looking for a super insulated space, currently heating with propane until get a gas line run, goal is to be able to have it 50 degrees without spending a fortune on heat for the weekend and the 1 or 2 nights/week working out there, rest of time likely kept in the 40 degree range. Couple pictures of the existing condition are below
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