My house consists of two units, the main and basement apartment to which the main is not connected indoors.
I was planning to put fiberglass insulation between the joists and use ultra light 1/2" sheetrock but then a friend told me to use 5/8 for fire resistance reasons. Assuming this is not subject to code inspection, would it be acceptable to go with 1/2"? I've seen sagging between joists as a reason but I'm not seriously concerned about that. In addition to being lighter and easier to work with, I prefer 1/2 to allow that 1/8" extra ceiling space, which is scarce.