I've spent some time looking at the Code of Ordinances (usually in a website called Municode) to find applicable codes. In this code of ordinances there are, sometimes, a history of revisions to that section of the Code of Ordinances. So if you can find that history, maybe you can get in touch with the City or Town clerk and find out what these revisions were and what they changed in the building code.
This is tedious and you're going to have to sweet talk the town clerk (who doesn't owe you anything) to get this information. Also the town library should have a history of the minutes from the board which if you go through enough, you can work backwards and find this out.
The Building Department could have be a little more helpful. Have you tried meeting them face to face? Sometimes people are more helpful to someone standing there, than a phone caller.
I hope you want this real bad, because this sounds like a major pain.