There is NO WAY I'd do what you are asking! Not unless you want to chop out a bunch of foam later and re-spray those areas.

How much could the rough-in possibly be? And no offense, but if money is so tight why the heck are you even going ahead with the project???

If this is a new home built with permits you will have a hard time getting a certificate of occupancy if it is not finished.

I would like to have all but one of the bedrooms and a second den be unfinished. As for the timing, I am still homeless from Hurricane Katrina, and I don't want to wait any more than I have to. Also, I have a loan @ 2.7% from the government for me to rebuild, and I can't put that off too much longer. And there is the $8K tax credit for building this year. And I have the ability to get a second mortgage, but only if there is a finished (i.e., livable) home first; otherwise I would need to go the route of getting a construction loan, which seems to be incompatible with the government loan, and would cost a few $K extra, and would be difficult to get in the current banking credit crisis. The bottom line is that this project must go on.

I don't want to build something small just to add on, as it would make much more sense to just build the entire outer shell at once, and just finish the rooms in the future. I don't need a lot of the rooms and only need one bathroom. Everything else is just going to have a door in front and bare framing and any needed plumbing rough in. I can get a certificate of occupancy as those unfinished rooms would be like attic space. All I need is that the outer structure to be complete (i.e., all the windows and doors, siding, etc.), have a working kitchen and one working bathroom. And believe me, I want to get everything on the lower floor complete (I had always planned on the upstairs being unfinished.) I had a bunch of cash to get me to the finish line, but that cash was invested in the stock market, and I don't want to sell at a loss (or at least not too much.)

The cost to rough in the wiring to just a few rooms would amount to less than $100.00 :(250ft. of 14-2= $45.00, dozen or so boxes at $2.00ea. ) so why not do it??????? You may be way over estimating the cost of rough in for just a couple of rooms. Especially when you figure in the fact you're building an entire house.

While I certainly do not agree with the $100 figure to have the rooms roughed-in, I do agree that roughing in these two rooms are negligible in the scope of things.

There's something I'm not getting here. If those rooms are going to be like attic space, with only windows, doors and siding, are you planning to spray foam from the inside directly onto the outer sheathing? With no inside walls?

As a practical matter, there really isn't a good way to get lines run once you spray foam.

As another practical matter, you really need to talk with your local inspector about your situation. It sounds like you are planning on doing things in a non-standard way. If you don't get the inspector's buy-in from the start, you could create a ton of headaches for yourself down the road.

Where exactly are you? The Gulf Coast isn't exactly known for picky inspectors, or in some areas even HAVING inspectors, but there are always local exceptions.. if you're in an area where the government is lax about construction stuff, you should pay especially close attention to the requirements of any loan programs you're going to be using. Are there HUD requirements attached to that Katrina loan? If there are they may not want to see unfinished rooms either.. definitely something to check on.

Roughing in electric for a few rooms with "normal" needs is CHEAP now, while the walls are open and empty. Since you need to save money now, I wouldn't go wild with networking cable and stuff, but I'd definitely put the required electric runs in and maybe even run a 3/4" flex conduit to each room to make it easy to pull phone/TV/etc as needed later.