i’m working a plan with three unconditioned areas in cz-6 and am looking for input on how to treat conditioned/unconditioned transition walls from an insulation perspective:

 

from top -> down

 

1. a “bonus-room” (over garage)

— i wanted to be able to throw a space heater in here on occasion and have it retain heat, so i was gonna insulate these exterior walls as if it was conditioned space (ie r-30)
— local energy standards specify that floors should be r-30, but i think that is referring to something like a cantilevered floor over the outside, not sure if it applies to a floor over an unconditioned garage?

— so how to treat the transition wall here because the space could be pretty cold when not heated, should i treat as r-30 exterior, or give some consideration to the fact that the unconditioned space has r-30 exterior walls too?

 

2. an attached garage

— since under bonus-room, thinking to go r-30 on these exterior walls and r-15 under the slab

— same question as above about the transition walls
— these transition walls are subject to fire-code if that matters from an insulation perspective

 

3. a 500 sf chunk of a partially finished basement

— seems like i don’t need to go full on r-30 on these transition walls as the unconditioned space will be r-20 foundation walls and r-15 under slab, but what would be pragmatic?