Large turnout as committee weighs state limits on local rules for accessory dwelling units

House Bill 577, a broad proposal to expand accessory dwelling unit (ADU) rights statewide, drew the largest turnout of the committee day and sharply divided testimony.

Representative Joe Alexander, sponsor and chair of the House Committee on Housing, said the bill responds to a statewide shortage of housing. The proposal would allow one ADU up to 950 square feet by right, attached or detached, preserve limited local control (for example, aesthetic standards and sewer capacity), and prohibit municipalities from imposing certain restrictions that the sponsor called “unnecessary barriers.” "This bill balances the need for local oversight with fundamental right of property owners," Alexander said.

Proponents included business and housing groups: the Business & Industry Association (Neech Grace) said detached ADUs are unlikely to flood municipal services because building an ADU carries significant costs, citing a rough construction cost of about $340 per square foot in parts of southwestern New Hampshire. New Hampshire Housing (Jack Reuterman) and Housing Action New Hampshire (Tom DeRosa) supported the bill as a modest, reliable way to increase supply. The New Hampshire Home Builders Association (Matt Mayberry) and the New Hampshire Association of Realtors (Joni McIntyre) also supported the proposal.

Advocates from AARP and other caregivers described personal stories of multigenerational housing and said ADUs can help older adults age in place and provide caregiver housing. Representative Peter Bixby and several producers noted the bill would also clarify confusion over existing ADU law.

Opponents and cautionary voices raised concerns about erosion of local control, septic and water infrastructure, parking, owner‑occupancy requirements and unintended land‑use outcomes. Brady Deshaies and other municipal planning representatives recommended preserving conditional‑use or special‑exception review so towns can address site‑specific issues. Roberta Oser, a longtime municipal planning board member, said removal of special‑exception review and owner‑occupancy requirements could allow speculative building or condominiumization of ADUs and urged stronger local oversight of septic and occupancy rules. Representative Len Turcotte argued the bill effectively changes single‑family neighborhoods and removes significant local zoning authority.

Proponents said an ADU mandate will not cause a surge of construction because costs are substantial and many homeowners lack capital to build; skeptics said the bill could change neighborhood character and voiced concerns about enforcement and the timing of municipal implementation.

Why it matters: Supporters view the bill as a practical, immediate tool to add housing supply and support aging in place; opponents see it as an overreach that weakens municipal land‑use controls and may shift burdens to towns and neighbors. The committee heard many written and oral statements and did not take a vote at the hearing.

If passed, the bill’s effective date and municipal implementation timeline were raised as issues by committee members and witnesses.