So, in my garage I walled off an area about 11.5" by 14.5" (167 sf) as a gym. The two walls I built are 7/16 OSB, one is cinder block and the fourth is the insulated garage door (and a few feet of cinder block). The ceiling is a little under 9’ to the bare rafters which are 2x9’s. I heat it when I am in there and am wondering if insulating the ceiling would be worth it.
Ideally I use the room 6 days a week, for 40min 3 days and 90min 3 days (alternating), but always at least 3 days a week.
From what I see, I can do it in R-13 for $110 or R19 for $128. I just am not sure how much of a difference it will make and if it really will pay off in the long term.
As another thought, would putting hard foam insulation on the walls make a big difference?
In high school (90s in South Dakota so quite cold), some local former high school athletes and now business people bought equipment for a rough gym in an old brick building (through a loading dock) downtown. It was open 2-3 hours per day after school. It was not insulated as there was no way to do it in such an open space. But the 2 bathrooms were with little in-wall heaters to keep the plumbing working. However, they just installed 2 industrial heaters+blowers that did a good enough job. If you were pumping and moving, you warmed up and got quite sweaty quickly and it was usually well below 50 and probably below 40 all winter other than in the direct heat lines. So I would just get a good (industrial?) space heater and move in front of it when you need it.
With only limited use per day, it doens’t make sense to heat it even minimally the rest of the time. And it will take too long to get to temp when you do need it. And if the heater solution isn’t good enough you can always insulate it later.
I used to lift in the uninsulated attached garage of my home in central Vermont. Never needed more than a sweatshirt and sweatpants. The costs of insulation you listed would, of course, be much cheaper than a gym membership if temperature becomes an issue.
As it’s attached to your house, any insulation you put in there will also slow down heat leakage from the house. And that heat loss happens every hour of the day, all winter long.