Trying to improve woeful thermal performance of chicago ceiling in multi apartment building.  Above the plaster ceiling there is a 2 ft airspace that provides space for sprinler pipes ducts and conduit.  Above this is R-38 fg batts loose fit in a 2×6 frame.  Needless to say the batts do not stay in place as there is no solid barrier to keep batts steady and thus cold air is leaking in many areas and causing entire ceiling to scan cold in an IR camera.  All ceilings are cooler than walls and perimeter ceiling areas are way cooler.  #1 problem is that you cannot put a worker onto the plaster ceiling as it is framed with steel strapping suspended from the upper 2×6 grid.  Any one ever found an effective remedy for such a site?  Unfortunately the architect has already fled the scene.   Metro Boston location..  Barmo