Originally Posted by woodworkbykirk
the only thing that will span 15' with todays materials are engineered joists
another option is to set a flush beam that runs down the middle of the space and then run joists that are just under 7'6" off of the beam, however consult an engineer first as what exactly to use and whats accepted by your local building authority as per codes
Not sure where you get that....
Cuz...according to the span tables used by Los Angeles County Building code....
24" OC would require a 2x6 ceiling joists to span up to 15' 6".
With a 2x8, you could go 20' 5".
Personally....I would go 2x6 on 16" OC. Makes doing the drywall a lot easier....remember, your going to be stagering those sheets.