This is simple, Jack. Just ask the building department or
whatever department issues building permits in your area
(actually you should have somebody else ask). I asked when
I had to reroof my house and here it is two times the
building permit (by the way that includes the building
permit) so $50 for a permit to build, $100 dollars if caught
building without the permit. Just make sure you follow
code.

One major issue is that once you get the permit aftert the fact, the
inspector may require removal of a portion of the work to inspect it.
In the case of the OP, that might mean proving the footings are to
code.

It's too late now, so just don't say anything, unless
they are really on top of things they will never catch it.

Most oftne it's a neighbor that rats you out.

BTW my building department says they were protecting me, the
owner (from whom?) by having to have a building permit.
They never could explain how they were protecting me. Ba!
Building permits are just a way of collecting money.

First, building permits *have* to generate revenue. That's what pays
for the building department. Permits protect you from future
litigation due to code violations. They do not esnure quality
workmanship, just that the work meets the current codes at the time of
the inspection.

This isn't a rant against building permits. Standards need
to be followed, but I don't believe homeowner repairs or
small projects should be included.

Repairs normally don't require permits. Neither do small projects.
For example, locally a concrete walk under 100 square feet doesn't
need a permit, but a larger walk or driveway does. Fences less than
50' long don't require a permit, and sheds under 100 square feet don't
either. Less than 1 sqaure of roofing doesn't require a permit, and
there's a provision for emergency work on roofs to repair storm damage
that allows permitting after the fact.

Of course here, a lemonade stand needs a permit...

I also got a building
permit for a small building that I put up, but my neighbor
and I put up a fence and later found out that a building
permit was required. I think they would have a hard time
enforcing that after 25 years.

You might find a contract for sale with a clause that states all
additions have been done to code and required permits obtained. You
can always strike it out though.

Jeff