NH HB1079

Expands the definition of accessory dwelling units (ADUs) to allow construction within or attached to non-conforming structures that existed on or before July 1, 2025

Redefines "attached unit" as a unit within or attached to the principal dwelling, and "detached unit" as one neither within nor physically connected to the principal dwelling

Requires municipalities to allow ADU conversions from existing structures including detached garages, even if those structures violate current setback or lot coverage requirements

Establishes eligibility criteria for ADUs in non-conforming structures, requiring applicants to demonstrate either preexisting nonconforming status under RSA 674:19 or prior zoning approval

Repeals RSA 674:73 regarding detached accessory dwelling units; takes effect 60 days after passage