I’m in zone 6 (north central New Hampshire) and just purchased a new house that was built in the 80s. I’d like to make a downstairs office in the unfinished basement. I plan to use a new run of radiator to heat the space off the boiler.

The basement is bone dry and has bare poured concrete walls inside. On the foundation exterior there is thick foam of some sort that stops above grade and is covered in some sort of (failing) stucco. I’m considering the following plan for the interior walls against the concrete foundation:

– Either XPS or foil-faced Polyiso, 2″ glued to the foundation, taped and sealed w/foam.
– Same as above in the rim joists, sealed with foam.
– 2×4 walls with R15 Rockwool batts.
– No vapor barrier.
– Finish with pine barnwood paneling.

Do I need to use sheetrock in this? Is the rockwool in the bays overkill?

Thanks for any tips.