Hi,

I’m renovating a home in climate zone 6B.  We are recycling as much building material as possible.  The exterior walls are 2×4 with 2″ mineral wool batts.  I have a lot of 3″ fiberglass batts from the ceilings that we removed.  Is it okay to compress the 3″ fiberglass and 2″ mineral wool into the 2×4 stud bay?  I know compression is okay but I don’t know if the double kraft paper has an adverse effect.  

The plan is to attach faced eps or iso (1-2″) with seams taped as the inner wall air barrier.  Then frame a 2×3 or 2×4 wall with batt insulation as the interior wall.  

Thanks,