Did you check to see if permits were ever pulled but final inspection never called for? I'd start with the building dept and do a permit search. If none was ever pulled then I would request an "AS BUILT" permit which most building jurisdictions will usually grant after performing a pre inspection to see that what has been done was done to code.
If it wasn't then the inspector will leave you with a list of correnctions but you should still be able to pull the necessary permit to complete the project and you will have to satisfy all the corrections before the inspector will final. Hope this helps.... more