I have a small cabin with an equally small loft - I built an addition onto it, and now I'm turning the entire cabin into a kitchen / pantry area. The original loft is going to be used just for storage now. The ceiling rafters join the loft floor (ceiling joists) at @ a 50 deg angle, and the rafters are already insulated from top plate to ridge (with rafter vents). No knee wall before this.
I put a short knee wall (16") up just to clean it up a bit - the tight angled space was just a major dust bunny collector and wasted space as most of the stuff I need to store is in boxes. The short wall also adds some real stiffness to the existing rafters too.
Do I need to remove the ceiling boards + insulation and expose the rafters in the area behind the new knee wall, then insulate the knee wall and turn this new area into a cold zone? Or can I just cover the new knee wall studs, leave the insulation as is (top to bottom along the existing rafter bays), and forget about it? The space behind the knee wall would then remain in the warm zone, but there would be essentially no air circulation once I cover it over).