Wow especially up there. Minimum for code here is R15 for 2x4 walls. I built my mini barn out of 2x6s so I’ll probably do R-15 stuff between the studs and put the 1 inch pink foam r10 stuff in. Roof I’m doing the bubble foil and then R30 plus foam r10. really overkill for a storage barn but I’m experimenting and have a few hundred on Home Depot gift cards to experiment with
Where walls meet ceiling, a foot long 45 degree panel to keep r value up continous through the corner helps a great deal. Brother in law did some research, infra-red tests revealed that as a common poorly insulated area.