Building permits and unfinished rooms in potential house

[Anja Brey]

Hi all, 

We are looking into buying this very cool victorian house from 1894 in Contra Costa County in CA. The house is a bit funky and contains a full functional living unit on the second floor but the ground floor, (basement), which is on a slab, seems to have been remodeled at some point, but not at all finished. I called the County and there seem to be not permits for the unfinished large room, bathroom and laundry room on the ground level, but for a new slab and underground plumbing from 2005.

We are thinking of buying the house and creating a studio on the ground floor and renting it out to a tenant.

We have never dealt with permits, and we would probably hire a licensed contractor for the electricity, plumbing, heating, floors, walls and windows, but would do the rest ourselves. 

What are things we need to consider when buying this property? Would you ask the owner to pull the permits for what he did in the past as a condition of the sales contract? The county told me that once I buy the property, I am fully responsible for everything, which could include code enforcement fines. 

Thanks so much! 

Anja