@Logan Vierstra
I concur with Sean. Good info there, I have had similar experiences in El Dorado County. One example: I bought a property that is on record as being 1000 square ft. I measured it at 1500 square ft. Turns out the sellers converted the garage. No big deal to me, they did good work and I figure I could always have the county do an as-built-permit to legitimize the square footage and (in theory) raise my property value for resale. I will probably wait to do that til right before I sell, if I ever do, as that would raise my property taxes, which obviously doesn't help my cashflow situation.
My best advice is to have your friend talk to a contractor and see what their opinion is of the situation and what an As-Built-Permit would entail. He should also go to the county, be vague (don't give address or full name or anything, call me paranoid if you want) and ask what they would require for an as built permit. My understanding is that their main concern is that there is no health or safety issues... i.e. GFCI outlets where needed, tempered glass where needed, smoke detectors, etc. If he does do this please update us on his findings, as I've meant to go to the county to ask for myself but I've been so dang busy I can't seem to find the time.
Hope this helps, and good luck. Feel free to reach out to me directly if you have any other questions about EDC REI. :)