airtight goodness or moisture problem?
Redoing the house we went with 3 inch exterior xps to be above dew point.
Inside in the basement I am looking at my rim joists.
Mayny places online say air tightness is key and under no circumstance should fiberous insulation be used.
I am concerned is I spray foam the rim joist I am makinging a structurally reducing mold sandwich.
My basement walls are 6 feet concrete then 2 feet then joists. The first 6 feet is 2 inch xps glued. The cement top has a 2x4 set into the outside edge (not treated/no vapor barrier/capilary break -1950s) I have not seen any rot along it anywhere.
From the out side I have 1 foot exposed concrete before the wall starts.
Is the whole area from cement to joist-top the rim joist or just the area the joists are in?
Any links to the/a proper method would be great