Re: Converting 2 story greatroom into 2 rooms
Shannon ... hiring an architect or engineer would be the right thing to do.
While the contractor that will be doing the framing should have a good idea of what will be required ... however ... a good contractor will also seek the advice of an engineer regarding the structure. The engineer or architect will advise you what is required.
It's impossible to say over the internet what is what and how with your home's structure.
Whether the joists will be dimensional or manufactured the closer together for spacing will provide a stronger floor combined with the size of those joists.
I have to agree that HVAC is a tricky venture and you should consider having a HVAC company run the supply and return ducting.
Hope this helps.
"" an ounce of perception -- a pound of obscure "