Adding square footage to an existing home - fix and flip

[Tasia Turner]

I am looking at a possible property to purchase and adding about 400-500 sf of extra living space (den/family room) would really increase the comps for this particular home. I am trying to figure out a ballpark number for adding on an extension. Does anyone have a good tool for evaluating this? Or a good cost/sf to use as a basis? I am located in Northern California and the house is in a rural area in El Dorado county. Thanks in advance. I look forward to hearing everyone's  thoughts on this :-)

[Alon L.]

It depends on labor costs and availability of the various trades in your area, but in LA, retail price to hire a general contractor to do that project would probably be about $250/sqft for the new structure and $100/sqft to remodel the existing structure (down to the studs), plus finishes, fixtures, landscaping and hardscaping.