Is there a way to insulate a ceiling that is already finished and has no access point? More details below:
Recently purchased a home in Eastern Massachusetts; one of the features was a room off the back that appeared to have been built as a screened in porch and eventually finished as a new family room. There's a gas radiator (though that doesn't work currently), so there isn't heat to the room, so I expected it to be cooler, but manageable. Unfortunately, I've come to find out it appears there isn't insulation in the ceiling.
The walls are almost entirely glass (there are 6 60" square sliding windows which I just replaced because the seals on the old windows were shot), so there is nominal wall insulation, but it is there. When changing the bulbs in the recessed light fixtures, I realized it was frigid up above. There doesn't appear to be an access port from the outside on either side of the room, and there's no entry point from inside the rest of the house.
I'm guessing that this won't ultimately be a DIY project, but is there even a technique to add insulation to a ceiling like this? I assume it's going to be blown in or foam of some kind, but I can't figure out what product would work well; it's a long room (20' end to end) and I don't know how to approach it. Any insights would be appreciated.