Retrofitting garage to a heated shop – slab and wall details
I am soon to be owner of a house with an attached garage, roughly 20×30. I would like to convert the garage to a heated wood shop.
I am in climate zone 6A (Maine). I will have consistent heat in the shop, probably in the 55 degree range, bringing it up to 60-64 for working temp. I am leaning towards heat pump as heat source.
The garage is a concrete slab, the details of the footings/stems I do not yet know however.
The structure is 2×4 studs sheathed with (I believe) T1-11 exterior ply. Roof trusses (not raised heel). Stud bays currently open to inside.
So my question in broad terms is what should my strategy be for insulating / air sealing.
What I am scheming is to build another 2×4 wall on the inside to create a double stud wall (insulated with dense pack and or rock wool), and then to blow in cellulose on the attic floor (and vent attic). I figure the thicker wall will help to mitigate the small triangle created by the non raised heel trusses.
The slab is where I am really scratching my head. My two thoughts currently are to add insulation over the concrete and/or to dig around the slab and install a frost protecting layer of insulation. Is insulation over the slab doable if detailed correctly (where to add the ?polyethylene?). I am also concerned about head space, but if this is generally advisable, how much and of what (eps foam?)
Thanks for any thoughts!
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