What changed after LD 2003
LD 2003 (effective 2023) is still the Maine baseline: municipalities must allow at least one accessory dwelling unit on a single-family lot. It is not the last word.
Maine LD 1829 (signed June 20, 2025)
LD 1829, Public Law Chapter 385, builds on LD 2003. Public summaries of the enacted law include:
- ADUs on lots that already have more than one unit, not only a single-family house
- Owner-occupancy mandates removed at the state level
- Towns cannot require fire sprinklers solely because of an ADU when the building has two or fewer dwelling units
- Higher statewide minimums for how many dwellings a residential lot can hold (three in many cases; four in designated growth areas with public water and sewer), still limited by lot size, frontage, and other dimensional rules
- Subdivision review threshold moved later so small multi-unit projects are not treated like a full subdivision
City-council towns and town-meeting towns have different ordinance-update deadlines. LD 2173 pushed those dates later than the first LD 1829 calendar.
Maine LD 2173 (signed April 16, 2026)
LD 2173, Public Law Chapter 733, is the cleanup bill. It clarifies that ADUs belong on lots with one-, two-, or three-unit buildings, tightens when sprinklers can be forced, limits planning-board process for four or fewer units, and extends municipal implementation. Press coverage in March 2026 also described compromises on lot-size floors and rate-of-growth tools. We read the town ordinance, not a blog post, before we stake a pad.
New Hampshire HB 577 (effective July 1, 2025)
Governor Ayotte signed HB 577 on July 15, 2025 (Chapter 197), effective July 1, 2025. It rewrote RSA 674:71–:73. Towns that zone for single-family dwellings must allow one ADU, attached or detached, by right. Municipalities may not set a maximum living area below 750 square feet. Many towns still cap ADUs near 950 square feet unless they authorize more. Setbacks and design rules that apply to the main house still apply. We confirm the town, not a statewide slogan, before we price a 981 sq ft Ella’s Retreat in New Hampshire.
What we tell owners
Bring the town and the lot. We pull the ordinance on the free consult. Maine and New Hampshire are both more permissive than they were in 2022, and both still leave setbacks, septic, and shoreland in local and state environmental hands.
Book a land review or a build scope.
Skip the guesswork — get instant pricing.
Our 2-minute calculator gives you a real ballpark for any project type in Maine or New Hampshire. Compare the published packages on the ADU models.
Price My Project