Accessory dwelling unit, unpermitted - questions

[Natalia Katoaka]

Hi all, my bf has a 4 bd single family home. We had been, until last month, renting rooms individually to professionals/college students since purchase. We'd like to not have 'roommates' anymore, so made the decision to wall off one of the doors and create a 2nd unit. The unit will be a 1bd/1ba, more similar in size/structure to an in-law unit (will have kitchenette & living space, separate bedroom, full bath, small yard & separate entrance). The living space and bathroom were unpermitted additions when my bf bought the home - this was not remedied with the city/county, so subsequent upgrades (minor - new windows, moving some outlets, removing a wall, etc) were also not permitted. 

I am wondering about implications making the home into 2 units as we are not permitting it. The door we will wall off will be able to be removed - we aren't removing the door itself. We will be installing a sink in one of the 'bedrooms', but no range, w/d hookups, furnace, etc. so when we eventually want to sell, those items can be easily removed.

Rentals are currently in huge demand in our area - we had a catastrophic wildfire about 10-15 mi from our home and people are desperate for housing, but I am becoming concerned as I've seen people recommending lying about ESAs to get their pets in rentals (we have 2 dogs already and wont accept pets), people reporting rental listings to the AG if they think the price is too high (gouging), along with the general worry over destructive/abusive/etc tenants. We've never used a management company before, but are seriously considering it now.

We are already too far in the process to stop and we are hoping to be ready by 12/1. Just looking for some general tips and implications that we need to consider before going forward with deciding on a tenant. We are in Sonoma County of California, if that helps.

Thank you!