How you insulate and the amount of insulation you require depends upon your location and your local building code or State's energy requirements.

Call your local code office for specifics.

do you mean inbetween the joists? in between the joists for controlling the cold feeling of the upstairs floor from an unfinished cool basement. put in batts of unfaced(no vapor barrier)insulation of r20. hold in place with stapled string to stop batts from falling out ,till in the future when you finish ceiling.

Hey Eagle. Do you recommend using unfaced batts because the paper on the faced batt needs to face the 'warm' side and in this case could not make a constant plane because it's in the joists? I want to make sure I understand why to use unfaced batts in this application.

Thanks!