Hudson, NH Accessory Structures: ADU Owner Occupancy (2026)

3, adopted under Article XIIIA (Amdt. No. 16, 1995; amended 2006 and 2017), permits an ADU only within a single-family dwelling that permits such use; it cannot go into a two-family or multifamily building, and it cannot be a detached structure, manufactured home, recreational vehicle or trailer added to the principal dwelling. Subsection C is the owner-occupancy rule itself: either the principal dwelling unit or the ADU must be occupied by the owner of record of the principal dwelling, and the Zoning Administrator (or any other official charged with enforcing the ordinance) can require the owner to prove that one of the two units is his or her principal residence.

3 layers on design and size controls that keep the ADU secondary: the front of the structure must still read as a single-family home after conversion, with any extra entrance moved to the side or rear (Subsection D); the units must share at least one common interior access and keep two means of egress (Subsection E); and separate utility meters for the two units are barred, though a different heating system for the ADU is fine (Subsection F). The ADU itself must run at least 350 and no more than 750 square feet, and converting space to an ADU cannot shrink the principal dwelling below 850 square feet (Subsection H); it may have no more than two bedrooms and no more than two unrelated occupants (Subsections I, M), needs its own interconnected fire alarm tied to the principal unit (Subsection N), and requires a building permit issued before any construction or conversion begins (Subsection J).

Four off-street paved parking spaces must serve both units combined, with no separate driveway for the ADU (Subsection G), and the ADU keeps the same house number as the principal dwelling with no separate mailbox (Subsection K). Only one ADU is permitted per lot in any district (Subsection L). 5.