Many jurisdictions allow a small dwelling to be built on a property with an existing home. These dwellings can be used as a home for extended family members or as rental units. ADA’s can be attached to an existing structure (as this one was) or be built as stand alone. With an aging population and lack of rental housing, these types of homes are getting very popular. Generally they are limited to 850 square feet maximum of heated space, but can have large decks and outdoor spaces.
There are restrictions so an initial meeting is important to determine feasibility. As always, initial meeting are at no cost.