Adding a Second Story

[Guppy]

You have a lot to think about!
I have 40 yrs in the business and the one most important suggestion I'll through out there is,,,, find yourself a quality builder,, designer or architect ($?).
If the codes are even close to what we have to go through here in MA you will need professional help. Permitting is a whole new trade now!!!!
If you are willing to spend a little more because of location make sure the resale numbers work for you down the road.

Septic??? Will the foundation support a second floor?? first floor walls,,,,
No two jobs are the same but more often than not we span the new floor joist from front to back with EWP. This eliminates the need to address any new gravitational loads other than the exterior walls.
best of luck

Oh to be young again , Gup

http://www.woodbywy.com/literature/TJ-4000.pdf