Per SB13: “would require any impact fees to be charged for an accessory dwelling unit of 750 square feet or more to be proportional to the square footage of the primary dwelling unit. ”So it depends how large the existing primary dwelling is.  

ACCESSORY DWELLING UNITS.The Legislature has given HCD particular authority to shepherd the development andapplication of State ADU Law.

In my town I had a similar question regarding buying a single family and adding a “accessory apartment” and the town code states that you must live in the property to have the apartment be legal.

One approach that I'd look into is an accessory dwelling unit*, a legal way to add a second unit to many existing SFRs in Cary and Durham.

Whether both accessory units can be in the main structure depends on the size of the house and lot and the relative size of the units among many other factors.   

Boxabl › homeWeb resultsBOXABL – Affordable Accessory Dwelling Units & Granny Flats.

Hi there, I run and educational resource for Californian property owners who want to build Accessory Dwelling Units (ADUs).

That separate space is considered, under this scenario, accessory to the primary use of the land. 

Towers come with own set of rules and regulations for fire, compliance, central mechanical, elevators, roofs, accessory rooms/office, and model units- this has been amazing experience working on building new efficiencies, implementing CAPEX with large NOI drivers - VeryExciting to have walked the gauntlet on the tower apartment versus garden-style - Truly expanded knowledge and experience.

Towers come with own set of rules and regulations for fire, compliance, central mechanical, elevators, roofs, accessory rooms/office, and model units- this has been an amazing experience working on building new efficiencies, implementing CAPEX with large NOI drivers - VeryExciting to have walked the gauntlet on the tower apartment versus garden-style - Truly expanded knowledge and experience.