Hello.
There is 1 workaround that i can think of. It involves detaching the face and mirroring the detached face, which gives you a copy of the face, with edges and vertices. (Remember, this is actually a reverse copy. You will need to 're-mirror the mirrored face again' to get an exact replica of the original face.)
But then you have the problem of the original face now being detached from your object. (the original ceiling is no longer attached to the room.
)
Theres the option of putting it back, with join solids and merge points, but that can sometimes be difficult to get it exactly how it was.
A trick i found here was to:
After mirroring the face(s), select the copy of the face, (the 'twice mirrored copy), cut, open a new object, and paste it into there.
Then, Go straight back to your original object. Hello, the 'undo' button is still active. (available).
Just click on the undo button until you are back to the point that you were before you detached the face(s).
Now the copied face is a complete new object, which can be copied and pasted back into the workarea of your original object. (the room).
Hope it helps.