NJ:
I cannot get a grip on the "square foot" pricing thing, never did, and probably never will.
Rehab, renovation, additions, etc. (resi) all require LABOR $$$$ (Gut jobs) and MATERIALS $$$
One 'system' could be use a floor plan, price it for BASIC NEC requirements, a bare bones resi, and win or loose, that's your price.
Experience; get a set of PLANS, bid the plans. "EXTRAS" are just that, more $$$
John
