It’s hard to say because it would really depend on the details like what kind of fasteners, strapping, sheathing, etc.

By sanitation area I assume you mean toilet and shower. In the floorplan I show a very simple layout. You could do something similar to the pallet house I’m building to section off the shower and toilet better.
http://www.tinyfreehouse.com/2008/08/17/wall-framing-plan-update/

I have not roofer my house yet but I still plan to use cans. I think painting them would help but eventually I expect the cans to rust.

You might consider using aluminum cans. IN fact I’ve been thinking about that too. They are a bit easier to get because they are everywhere but there would be a lot more prep time involved.

Check out this How-To article on instructables:

http://www.instructables.com/id/Make-Shingles-and-Siding-Out-of-Aluminum-Cans-Bee/

The in-law unit would have fewer obstacles I bet.

Shipping containers are very popular but I suspect they aren’t quite as turn key as one would suspect. They really only provide the shell, which is not that expensive to build out of wood. You’ll also be limited by the size and shape. I don’t think you’d have too many challenges getting it approved, more and more are being built, but I do suspect it would be quite a lot of work.

With conventional framing you’ll find a lot of people with tons of experience to help and the cost is low.

Good Luck! Love to hear how it turns out.

-Michael

I personally think a larger pallet house could be built and be perfectly suitable for living but it is not ideal and would probably be a nightmare to get approved by any planning department. It is also difficult to build with pallets. I would suggest building with normal dimensional lumber if it’s available. It can be very inexpensive to build a simple framed structure if you’re careful in design and choice of materials.

You might also consider researching the zoning of your lot. You might find that multiple units are allowed. Often the square footage of multi-family units is different and you might actually find that you can built a duplex smaller than you can built a single family residence. At the very least half of the duplex could be rented out.

Another idea is to find out if ADU’s (accessory dwelling units, aka in-law house) are allowed. Build one of those in the backyard to live in and then take your time fixing up or replacing the old house.

But my biggest piece of advice is to keep it simple and be frugal when choosing materials. The framing is cheap compared to other costs like interior trim and finish, bathrooms, kitchens, and windows. Keeping things like plumbing all in one area of the house can keep costs down. A simple roof with a simple low pitch can also be much less expensive than more ornate roofs.

Good Luck!