One of these days, I need to insulate my upper garage. My garage is built like a bank barn - lower level, 3 garage doors 2 cars deep. Above that, an unfinished 2 BR apt (bare studs, no ceiling, subfloors, some lighting). Behind that, a 40x40 workshop. I use the lower level for parking only; repairs are done in the upper-rear workshop. The apt? Parts storage, tool storage, and motorcycle workshop area (lift, workbench, tools, compressor, as well as some machine tools for the main shop like my drill press, hydraulic press, band saw, etc). But, the motorcycle area is HOT in the summer, and cold enough I stick to tools in the winter. Exterior walls are 2x6 studded so I have plenty of room for HEAVY insulation; I need to hang a ceiling so I can insulate above it...just haven't gotten around to spending that much on something so....not glamorous.
I did sell my old house a few years ago. I lived there for 17 years, then moved to my current house and rented the old house for a decade. Time came to sell it, and I did a TON of work to it. Same feeling as above - "man, this place is NICE now...am I sure I want to sell it??" - but I'm glad I did. I have too many things to take care of as it is...having another home on the list (I still have my rental duplex) would just have been too much.
