Looking to buy a SFH in one of these counties, with the intent to convert a basement into an ADU and rent it out (short or long term) - and live in the main unit as owner-occupied.

I assume you haven't occupied the unit in the past 5 years and don't qualify for any of the tax exclusion? 

The existing buildings only occupy the front portion of the lot, leaving about .4 acres of vacant land.  

Even though they wouldn't be occupied, we would still get a multiple on their future revenue stream. 

The unit I want to occupy has 3 people living in it, when is it safe to give them a notice to vacate and does anyone have a template for this?  

We need to go from the 70-80 building permits (per the planning dept) issued a month from 2019-2022 to about 15 to 20 per month outside of true owner occupied or LTRs. 

The property is rented by DCFS ( department of child and family services) a government tenant and are occupying the building for last 30 years and have no plans of relocating.

You'll get better loan terms and lower interest if you owner occupy. 

All the properties are occupied, but they need to be remodeled.

I have proivided the link below for your convenience:https://codes.iccsafe.org/cont...In accordance with 14B-12-1207.2"Occupiable spaces and corridors shall have a ceiling height of not less than 7'-6" above the finished floor"However, immediately following that note; the code then lists a few "Exceptions" to meeting this requirement.