Framing and Sub-Flooring - how many people for this job?

I am going to hire somebody to help me put in a new floor 9 feet above my livingroom (which is currently vaulted). We'll be hanging 2x10 joists (15 feet long) using strongtie joist hangers to attach to a band (ledger board), the bottom of them will be 9' off the floor.

How many people do I need to help me do this? (ie. is this a 2 or 3 person job?)

Also, wondering how long the lag bolts need to be that will attach the 2x10 ledger band to the studs.

I would want the third guy there, at least until the framing is done.

Are the ends of the ledger board going to sit on the top plate of the perpendicular walls. If not, I would recommend making it a header. I wouldn't use lag bolts thicker than 5/16.

The band/ledger board won't be "sitting" on anything, it would just be secured to the studs with lag bolts, with the joist hangers nailed to the band. I'm wondering how many lag bolts it needs (and how long), because the contractors all have different ideas about that. Does this sound correct to you so far?

Just an observation. Although a 2x10 in Yellow Pine with a live load of 40 psf and dead load of 10 psf will span 17', I have reservations on using them for floor joisting for a 15' span. Have you considered TJI joists (Silent Floor)? I would just feel better with the added strength for anything you may have on that floor.

I'm also looking at some kind of extra strength but I'm looking at extra support on the ledger board to keep some of the weight off the lag bolts. To get a good bite on the studs, I would say 4" lag bolts are needed.

Likewise, I would like to see inletting of the floor joists somewhere, either beside the existing studs with jack studs installed, or something like that.

The ledger with lag bolts should be engineered for size, length, spacing (not just on the studs), and placement on the board.

The interior wall holding up the other end of the new floor joists may not have enough support under it to carry the new additional load.

You will definetly want to pull a permit for this as if done improperly you would put your family's safety at risk. They may require stud bay solid blocking with through bolts for the ledgers and special straps for shear loads. Things that a lot of homeowners and even members here are unaware of that a Structural Engineer would know. Then the S.E. would be liable for the success of your floor system, not me or you.
Be safe, Gary

You could double up your ledger boards and add some Structural/comestic designer style post to the living room for extra support under them. would give a great deal of structural integrity to the new floor while adding some character and fresh design to the existing living room.

Just a suggestion of something i would probably do in this situation!