Hello, I am thinking of finishing a basement in my old house in San Francisco, it's horribly humid and that humidity permiates to the floor above. Some insulation, dry walls and new windows should help keep things tighter and dryer and it should be fairly straightforward to get permits for that... except for the staircase leading into the basement, which is 3 inches narrower than a normal staircase to code should be. It's been like that since the house was built in the 1930's.

Does anyone has any experience with that scenario? Would the building department deny a permit application for any sort of construction in the basement because of a legacy staircase not to code? Widening the staircase is a non-starter: it's between two beams and the walls on the level above would have to be moved too! More project that I am willing to take on.

Any advice would be appreciated!