My name's Kel.
Are these joists just supporting the ceiling or is there load from a floor from above?
If there's load from a floor above, what's it used for?
Are there any partitions or walls bearing on it?
This would basically be a drop ceiling, carrying none of the above weight, just sheetrock, screws and glue. This is an older house with balloon framing so I plan to tie the joists directly to the ouside walls studs as was done with the original studs.
the question about walls or partitions was about the floor above, since this is not carrying weight, doesnt apply correct?
You are correct. Since it's a dropped ceiling don't have to factor in floor, wall or partition loads.
Assuming you're using Spruce Pine Fir #2 & Better
if you frame @ 16" on center using 2x10 you'll keep the deflection or sag to a minimum.
If noise is an issue
you might seal all penetrations and add insulation to deaden sound.
Have I answered you question?
I think I'm almost there. When you mentioned deflation and sag, are you referring to joist sag or the 1/2 drywall sag that could occur from spanning more than 16" ?
I could go with 5/8 to increase the distance between joists, and you're correct this is a sound proofing concept so 5/8 would benefit me there as well.
I was referring to the joists sagging.
Highly recommended to frame 16" OC. That will keep the joists from sagging too much and the 1/2" drywall won't belly.
Ok thanks. I didn't realize the distance between joists affected how they might sag in the center of a given joist. I thought that had everything to do with the dimension of a joist, and how far it spaned unsupported.
The distance between joists is critical.
The fewer the joists the more each one works.
The more it works the more deflection or sag there'll be.