Easing of regulations regarding Accessory Dwelling Units (ADU) commonly known as "Granny Flats" is becoming common throughout most of the states now to alleviate housing shortages. ADUs are residential units built on property occupied by a single-family house.
Typically, these are apartments either within an existing home or free standing on the home site. Regulations are promulgated typically by municipal building or zoning departments and are usually quite site specific, mainly to maintain existing neighborhood ambiance.
This situation can become a boon for elderly people looking to downsize their residential needs without having to leave their familiar surroundings. For instance, they can build a smaller free-standing residence to live in and allow their care givers or potential care givers to occupy their primary home without having to buy land to build on.
Care givers can be close at hand but not under foot. Occupants of the primary residence may be family, but local regulations may now allow non-family occupants in the primary residence.
If you or anyone in your family are in the situation described, it might be of interest to investigate local ADU regulations.
Also the cost of adding/digging water/sewer/electric/gas lines to the flat. Higher homeowner's insurance, and higher liability insurance. When it comes to selling the main house along with the granny flat, the amount of buyers will be less as this is a unique situation.
One concern is when the granny flat is no longer being used for an elder. What would the owner do? Use is as a home office would be great as the door to the flat is separate from the main house thus a business expense for income taxes, or rent the building to tenants [one, two or maybe 3 people]? Singles or a small family?
Lot to think about.
Where I live there are a lot of over the garage apts and small house behind the main house built years ago when zoning laws were pretty non-non-existent. Then the zoning laws came in and that stopped.
It will work well in some situations. The individual would have to be able to live independently.
If someone needs care around the clock it wouldn’t do any good for their caregiver to be in a separate household, even if they are right next door.