insulating and dropping bonus room ceiling from 13' to 9' over living space

[loren cossette]

Should read under living space.
what codes do i need to be aware of?

[Mark Fisher]

Are you moving any wiring or smoke detectors?
Are you going to be changing or covering any windows or exterior openings?
Are you going to be blocking an attic access?
Are you installing a drop ceiling or a 'hard' ceiling with new framing?
What are you doing with the old ceiling and insulation? Will you be insulating the 4' of walls in between the new and old ceilings? Are you planning to vent the space between the 2 ceilings?

[loren cossette]

Are you moving any wiring or smoke detectors?
Are you going to be changing or covering any windows or exterior openings?
Are you going to be blocking an attic access?
Are you installing a drop ceiling or a 'hard' ceiling with new framing?
What are you doing with the old ceiling and insulation? Will you be insulating the 4' of walls in between the new and old ceilings? Are you planning to vent the space between the 2 ceilings?

electrician moved smoke detector.
hard ceiling. 24' center 2x4, plan on using 5/8 wallboard for ceiling.

[loren cossette]

electrician moved smoke detector.
hard ceiling. 24' center 2x4, plan on using 5/8 wallboard for ceiling.

old ceiling has unfaced ins,walls to be ins.

[Mark Fisher]

Should read under living space.

What do you mean? What is above the ceiling - conditioned or unconditioned space?

You didn't give room dimensions, and I don't have my span tables handy, but using 2x4 joists on 24" centers, especially with 5/8's drywall, means a very short span.

You are essentially changing the location of the thermal boundary of the building envelope. You need to take this into account when deciding how and where to insulate, how and where to ventilate, and how and where to air-seal. I'll leave the code references to others, but these are the areas that I see screwed up more often than not.