Revision: Jan. 15, 2025, 3:58 p.m.
HB 577 - AS INTRODUCED
2025 SESSION
25-0119
06/02
HOUSE BILL 577
AN ACT relative to modifying the definition of ADUs.
SPONSORS: Rep. Alexander Jr., Hills. 29; Rep. A. Murray, Hills. 20; Rep. D. McGuire, Merr. 14; Rep. Damon, Sull. 8; Rep. Grill, Hills. 18; Rep. Sweeney, Rock. 25; Rep. Mazur, Hills. 44; Sen. Innis, Dist 7; Sen. Murphy, Dist 16
COMMITTEE: Housing
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ANALYSIS
This bill expands accessory dwelling units by right to include detached units, adds definitions related to accessory dwelling units, and increases the maximum square footage.
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Explanation: Matter added to current law appears in bold italics.
Matter removed from current law appears [in brackets and struckthrough.]
Matter which is either (a) all new or (b) repealed and reenacted appears in regular type.
25-0119
06/02
STATE OF NEW HAMPSHIRE
In the Year of Our Lord Two Thousand Twenty Five
AN ACT relative to modifying the definition of ADUs.
Be it Enacted by the Senate and House of Representatives in General Court convened:
1 Accessory Dwelling Unit Definition. Amend RSA 674:71 to read as follows:
674:71 Definition.
I. "Accessory dwelling unit" means a residential living unit that is [within or attached to] located on a lot containing a single-family dwelling[, and] that provides independent living facilities for one or more persons, including provisions for sleeping, eating, cooking, and sanitation, on the same parcel of land as the principal dwelling unit it accompanies. Accessory dwelling units may be constructed at the same time as the principal dwelling unit.
II. “Attached unit” means a unit that is within or physically connected to the principal dwelling unit, or completely contained within a preexisting detached structure.
III. “Detached unit” means a unit that is neither within nor physically connected to the principal dwelling unit, nor completely contained within a preexisting detached structure.
2 Accessory Dwelling Units. RSA 674:72 is repealed and reenacted to read as follows:
674:72 Accessory Dwelling Units.
I. A municipality shall adopt a zoning ordinance pursuant to the authority granted in this chapter that shall allow accessory dwelling units in all zoning districts that permit single-family dwellings. One accessory dwelling unit, which may be either attached or detached, shall be allowed as a matter of right. The municipality shall allow one accessory dwelling unit without additional requirements for lot size, except as described by this section, setbacks, aesthetic requirements, design review requirements, frontage, space limitations, or other controls beyond what would be required for a single-family dwelling without an accessory dwelling unit. The municipality may not impose greater requirements for a septic system for a single-family home with an accessory dwelling unit than is required by the department of environmental services. The municipality is not required to allow more than one accessory dwelling unit for any single-family dwelling. The municipality may prohibit accessory dwelling units associated with multiple single-family dwellings attached to each other, such as townhouses. The municipality may prohibit accessory dwelling units associated with rented or leased land. Subsequent condominium conveyance of any accessory dwelling unit separate from that of the principal dwelling unit shall be prohibited, notwithstanding the provisions of RSA 356-B:5, unless allowed by the municipality.
II. If a zoning ordinance contains no provisions pertaining to accessory dwelling units, then one accessory dwelling unit shall be deemed a permitted accessory use, as a matter of right, to any single-family dwelling in the municipality, and no municipal permits or conditions shall be required other than building permits, if required by statute.
III. Attached accessory dwelling units shall have either an independent means of ingress and egress or ingress and egress through a common space shared with the principal dwelling. However, the municipality shall not limit the choice of ingress and egress.
IV. Any municipal regulation applicable to single-family dwellings shall also apply to the combination of a principal dwelling unit and an accessory dwelling unit, including but not limited to lot coverage standards and standards for maximum occupancy per bedroom consistent with policy adopted by the United States Department of Housing and Urban Development, provided that such municipal regulations shall not be more restrictive for accessory dwelling units than for any single-family use in the same zoning district. If a municipality has established regulations requiring parking for the principal dwelling unit, it may require up to one additional parking space for each accessory dwelling unit. Required parking spaces may be provided either on-site or at a legally dedicated off-site location, at the property owner’s discretion.
V. The applicant for a permit to construct an accessory dwelling unit shall make adequate provisions for water supply and sewage disposal for the accessory dwelling unit in accordance with RSA 485-A:38, but separate systems shall not be required for the principal and accessory dwelling units. In order to comply with this paragraph and prior to constructing an accessory dwelling unit, an application for approval for a sewage disposal system shall be submitted in accordance with RSA 485-A as applicable. The approved sewage disposal system shall be installed if the existing system has not received construction approval and approval to operate under current rules or predecessor rules, or the system fails or otherwise needs to be repaired or replaced.
VI. A municipality may apply aesthetic standards to accessory dwelling units only if it has also applied such standards to the principal dwelling unit. The total living space of the accessory dwelling unit shall not exceed 950 square feet unless otherwise authorized by the municipality.
VIII. A municipality shall not require a familial relationship between the occupants of an accessory dwelling unit and the occupants of a principal dwelling unit.
IX. A municipality shall not limit an accessory dwelling unit to only one bedroom.
X. An accessory dwelling unit may be deemed a unit of workforce housing for the purpose of satisfying the municipality's regional fair share obligation under RSA 674:59, III if the unit meets the criteria in RSA 674:58, IV for rental units.
XI. A municipality shall allow accessory dwelling units to be converted from existing structures, including but not limited to detached garages, regardless of whether such structures violate current dimensional requirements for setbacks or lot coverage.
XII. A municipality shall not deny the establishment of a separate electrical panel and separate electrical service to the accessory dwelling unit.
3 Detached Accessory Dwelling Units. Amend RSA 674:73 to read as follows:
674:73 Detached Accessory Dwelling Units. A municipality [is not required to but may] shall permit one detached accessory dwelling [units] unit. Detached accessory dwelling units shall comply with the requirements of, and any municipal ordinances or regulations adopted pursuant to, RSA 674:72, IV through IX. [If a municipality allows detached accessory dwelling units, it may require an increased lot size.]