Thanks for the replies. I have received a zoning variance for the structure. That means that it has NOT been "rezoned" as commercial, but an exception for my use has been granted (at great expense and almost 8 month battle. If I'd known going into it what I was getting into I would have thought of something else to do with my time, but that's a whole different story...) I am going to go to the local code department, for sure. My understanding, after talking to them last time about window requirements, is that this is not a commercial building and it is subject to IRC 2003. However, I am mildly afraid that I'm going to get a different opinion from each different person who looks at this thing.