Good point! Minnesota, so -40 to 110 degrees. North facing garage opening, 20x42 (tandem). Infloor heating but only in the back 20x20 portion. It takes a long time to heat up but it's infloor and only 1/2 the garage. The ceiling is a mix of R40 and r19. I'm going to address the r19 part but it will require a false floor built on top of what's up there (storage trusses)Insulation questions without location info and how it's currently performing won't go well.
Info on the rest of the structure, exposure, and hvac are all helpful too