Small 1960 ranch, roof trusses spaced 24" with a center sloped cathedral ceiling over the living room / kitchen, giving about 2-1/2 additional feet of height at the peak.
The wall at either end of the cathedral ceiling area was balloon framed. Demo'd the adjacent powder room and found the stud bays open into the attic.
Both the living room and kitchen are warmer in summer and colder in winter, despite having been airsealed and cellulose blown in the attic. I believe what happened was the contractor realized the walls were open after he estimated the job, and left them open. I found out later the blown insulation was shorted and the endwalls left uninsulated. They did come back after a complaint and put some faced fiberglass on the endwalls but did not do a good job.
I would like to have additional cellulose blown in, and the endwalls properly insulated. Apparently code allows rockwool to be used as a fireblock. This would be helpful as fitting short lengths of 2x4 into the stud bays would be very difficult if not impossible, part of the endwall takes a jog over a closet where the additional ceiling height is only about 2'. I understand code requires the rockwool to be stuffed down into the stud bay about 16" below the attic floor, is that correct?
Am I on the right track here? Any advice from those with experience with a similar project?
