[hinkley]

The thing I learned when we fixed our old house up for sale, is that in some municipalities you need a building permit to replace a floor that already exists with a new one. In our case water damage was from a claw foot tub drain, which I had fixed but years after the problem started, so it was in the middle of the floor. The contractor ripped it down to the joists and doubled them, which does not it turns out require a permit.

Sounds like your guy had a similar experience.