Maybe I'll luck out and the vaults won't need remediation. Yes I was thinking fibers, not foam. I'm sure I'm underestimating the effort eeded to do a proper job on the vaults within the things' narrow confines: Access to two of four vault edges doesn't seem possible without punching through the gables from outside.
Thank you for the practical suggestions on moving forward. Email me in profile if you're in Largo or Sarasota FL sometime and I'll buy you a brewski or coffee or something.
For retrofit, I think it is more common to cut 1-2 inch openings through the ceiling or wall face (i.e. cut through plaster or remove pieces of paneling), blow the insulation, and finally patch those holes. And, this pattern will repeat every 5-10 feet, since the bays should be physically divided along their length by fire-blocking if built to code. Each blocked section will have to be filled as a separate step.
Thank you for the practical suggestions on moving forward. Email me in profile if you're in Largo or Sarasota FL sometime and I'll buy you a brewski or coffee or something.