ADU

ADU
An accessory dwelling unit is a really simple and old idea: having a second small dwelling right on the same grounds (or attached to) your regular single-family house, such as:
 
  • an apartment over the garage
  • a tiny house (on a foundation) in the backyard
  • a basement apartment

Though accessory dwellings are an old idea (think of the old alley apartments in DC, or the carriage houses you see in fine old Seattle homes), they fell out of favor in the middle of the 20th century.  Now, however, they’re coming back, and they have lots of names.  Planners call them ADUs (Accessory Dwelling Units), but they’re also known as granny flats, in-law units, laneway houses, secondary dwelling units, and a hundred other names.  ADUs can be tiny houses, but tiny houses aren’t always ADUs.

People build them for lots of reasons, but the most common goals, according to one study, are gaining income via rent and housing a family member (accessorydwellings.org).
 
For information on ADU's in New Hampshire please see the following documents below: