I'm going to throw Jack's usual disclaimer about this applying in my area (Virginia) and the fact that it may not be true in your area onto the front of this post.
OK with that nonsense out of the way, I've spent the last 10 years or so of my career in one facet or another of structural design, a lot of it working with builders to help them get their plans designed and through the permit process. Most states have moved to the IBC (International Building Code) in the past few years so most of this should apply. When the states adopt the code they can adopt some, all, or some and add their own stuff, so you do need to check with your local building official.
The building codes are prescriptive ,meaning they provide a prescription which if followed will result in a "safe" building. The codes are not proscriptive, meaning they do not say that methods not covered in the code will result in an unsafe building. The code (IBC 2003 and later) has provisions for proving that alternative methods are satisfactory. A lot of these methods are outside of the means of a normal individual to meet, and involve test structures and long term monitoring. The two methods that are easiest for the homeowner to achieve are:
1) Hire a licensed expert, read architect or engineer with a seal for your state. If one of these individuals is willing to put their stamp on something they effectively remove responsibility from the local govt.
2) "Prove through anecdotal evidence", meaning find examples in your area that show the type of construction you want to undertake, and that do not exhibit any issues that are a result of that aspect of the construction. This one is real tough and should be a last resort. About the only example I've seen of this working is when a person has a buddy who has already built an alternative home provides the engineering he used to get his house built to the guy trying to get something approved.
Those are the two most official ways to get something unusual through the process. That said you'd probably be surprised how willing some building inspectors will be to help you out. Most of these guys are regular people and are more interested in construction that most people. They see hundreds of the usual cracker box go up every year and most of them like to see something different. They're just like everybody else out there and they get pleasure from being involved in something special. Your project could be that something special. Just remember most of these guys see their job as protecting you the resident from unsafe conditions caused by unsafe practices. They aren't busting your balls for the joy of it (unless you've given them a reason to enjoy it...) There are going to be some real jerks out there just like every where else, and it might not be a bad idea to go in and get a feel for who's who in your local office before you start a real out there project. Stop in and ask some questions be nice, sell yourself, before you sell your project nobody likes to tell their buddy no.
As an aside I mentioned the long term testing thing earlier in the post. If you have a state funded engineering college around they are frequently involved in this kind of thing. Here in VA we've got Virginia Tech and they're frequently involved in these kinds of projects and are a great source of info. They can not only help you out with finding projects going on in your area but can also provide great info on benefits and problems with different methods that are specific to your area.
