Floor covering is the aptest description since everything below the substrate can be considered the real floor in terms of structure and permanence.
Decorative wood between floor joists ceiling.
Called a floor covering or finish floor this might be ceramic tile solid wood laminate engineered wood luxury vinyl carpeting and many others.
Straight gable roof framing is assumed for selection table.
For finished ceilings first disconnect the electricity and remove all light fixtures and other obstacles.
Floor joists and ceiling joists serve similar purposes.
Unless you have a finished attic the ceiling joists are typically exposed.
Floor live load of 40 psf between the kneewalls.
Attic and floor dead load of 10 psf.
Bonus room floor joist selection guide.
Adjustable galvanized steel joist hanger tab 6 piece per box.
Owt ornamental wood ties ironwood 6 in.
Lower ceilings shrink the volume of the room to be heated.
Ceiling drywall hides the unpainted unfinished wood of joists beams or the floorboards supported by the beams plus a lot of other junk detailed below.
Generally floor or ceiling joists run parallel to the rafters.
You would be able to check if this is the case in your home by going up into the attic.
Ceiling board allows you to heat your room far more efficiently.