This bill proposes an amendment to RSA 674:16 to allow for the expansion of single-family residences into two residential units within residential zones in urban areas without the need for discretionary review or a hearing, provided certain conditions are met. The expansion is permitted by right for lots of 2 acres or less and for at least 50% of all lots zoned for single-family residences in a municipality. The conditions include restrictions on demolition or alteration of housing subject to affordability covenants, limits on the demolition of existing exterior structural walls unless certain conditions are met, and location requirements outside of hazard risk areas. Municipalities may impose objective zoning, subdivision, and design standards, but these standards cannot physically preclude the construction of two units of at least 1,250 square feet each. Setbacks for existing structures or those constructed in the same location and dimensions as existing structures are not required, but a municipality may require setbacks of up to 3 feet from side and rear lot lines in other circumstances.

The bill also outlines additional conditions that municipalities may require, such as off-street parking, proof of septic system capacity, impact fees for new connections to municipal water and sewer services, and the ability to disallow developments in areas with inadequate water or sewer capacity for up to 10 years. However, after this term, previously delayed housing developments must be allowed. Municipalities can deny proposed housing developments if there is evidence of a specific adverse impact on public health and safety or the physical environment that cannot be mitigated. Rental terms for units created under this amendment must be longer than 30 days, and applications cannot be rejected solely because they propose adjacent or connected structures, as long as they meet safety standards and allow for separate conveyance. The act will take effect 60 days after its passage.