Codes and inspection requirements vary from place to place, and it is always best to check everything with your local Building Inspection Department before beginning.
Not only can you be fined for violations, but if you ever try to sell your home with unpermitted and uninspected work, you may in for a very nasty surprise that might include tearing it all out, and doing it to code with a new permit.
In most places, residences must only meet codes for the year that they were built, and if there has been an addition, the addition has to meet code for the year that it was built.
In almost all cases now (at least here), a home sale involves a licensed General Home Inspection prior to closing. If something is discovered that isn't right, it usually has to be corrected at the seller's expense.
Mike
(NC Real Estate Broker)