A description of existing conditions (please, please forgive me if I've written too much. I'm not a contractor and I don't know what bare-bones facts are needed):
Our home was built in 1938 with a simple attic crawl space. In 1943 a permitted addition was built on the back of the house, comprising two rooms: a large family room/den, and something that might be called a utility room, mudroom, laundry room, or pantry.
Both have "gabled" ceilings. Or, I should say, just the underside of the roof.
In the family room it looks as though beams were attached to the underside of the roof--probably right against the plywood--then stained, and squares of noise-insulating panels were placed in the spaces between the beams. These beams aren't joists--there are no crossbeams--and seem to be entirely cosmetic. I've never seen what is behind those noise-insulating panels. I'm assuming it is simply the plywood that makes up the underside of the roof. There do not seem to have been any moisture problems at any point (we live in southern california), and those panels do provide a modicum of insulation against the heat.
As for the laundry room: as was fashionable at the time, the whole thing is walled in knotty pine. The ceiling is comprised of pine boards and the roof rests right on top of them: you can see the plywood between the 1/4" spaces between the pine boards. The sun bakes the dark roof and the heat radiates right into the room.
As much as I love the high, slanted "ceilings" we desperately need to install real ceilings in these back rooms, something with insulation or at least an air space to provide a buffer. All instructions that I have found ****** say that this is, essentially, a process of attaching some sort of ceiling to the joists. But there are no joists in these rooms.
As for dropped ceilings: I have yet to see an example that doesn't make the room look like a dentist's. I'd prefer wood-paneled ceilings or drywall...
What are the options?