The 203k can be used for primary residence owner occupants on 1-4 unit dwellings, which includes duplexes, triplexes, and 4-plexes. 

They consist of multifamily dwellings ranging from duplexes to quads.

I'm seeking advice on how difficult it may be to convert a SFH with an ADU (accessory dwelling unit) into a legal Duplex.

"(3) (A) A local agency, special district, or water corporation shall not impose any impact fee upon the development of an accessory dwelling unit less than 750 square feet.

The policy is triggered when one of the underlying policies (home, dwelling/fire, auto, boat, etc...) listed on the policy has a claim that exhausts its limits.

Not sure what you'd call this, but when we bought our sfh back in 2016 California had just passed the Accessory Dwelling Unit ADU law.

Then California passed the law legalizing Accessory Dwelling Unit's (ADU's) in January 2016.

Could be next year.Refinance that loan as an owner occupied property to a loan that doesn't have a deed restriction and then, after the required period of time (if there is one in the deed), then move out and rent away.Your homeowners will need to be switched to a fire and dwelling policy which will be sent to the lender, so follow the rules you agreed to in the deed for the new loan.Stephanie

The city website states the RT4 district is to promote, preserve and protect neighborhoods intended primarily for 2-family dwellings while also permitting a mixture of single-family dwellings and small multi-family dwellings of 3 or 4 unit.

Rental dwellings of four or less units, where one unit is occupied by the owner; 2.