Hi all, 

I’ve found loads of useful information and insight on this site and forum. We need to insulate the lower level of our house. This space is basically a basement that is all above grade (slab and cinder block walls with stucco and rock facade). It was built in 1994 and my best guess is that the original plan was to backfill around half of the house (it is on the side of the mountain), however, this wasn’t done, so it is all above ground with NO insulation!

The lower level has a few partially finished rooms with wallboard over 1/2″ sheathing directly on the wall. Needless to say, it is cold in the winter and there have been humidity/moisture problems behind some of the wallboard. 

My plan is to use InSoFast Max 3.75 with an R-value of 15.9 stated on their website (https://www.insofast.com/products/max-3-75-continuous-insulation-panel-6-box).

Is this sufficient for Zone 5 (Western NC)?

There are small gaps between the slab and wall in a few areas. Foam and a sill sealer under the rigid insulation panels? Just trying to think this through.

Thanks!