ADU rules in Lincoln

Lincoln adopted the state's three by-right circumstances nearly word for word in § 260-9M(1): one ADU per lot is allowed by right on an owner-occupied property as a reasonable accommodation for family members with disabilities, on any lot of 20,000 sq ft or more whose primary use is residential, or inside the existing footprint of the house or an existing attached or detached accessory structure. A new detached backyard unit therefore needs a lot of at least 20,000 sq ft (every conforming lot in RA-40 and RS-20 qualifies; most RS-12, RL-9 and RG-7 lots do not) unless it converts an existing garage or outbuilding without enlarging it. The use table marks the ADU row 'P' in RA, RS, RL, RG, BL and VCMU, but the ordinance lists no other path (no special use permit) for ADUs outside the three circumstances.

An internal conversion (basement, attic or other space inside the existing footprint of the house) is by right on any residential lot under § 260-9M(1)(c), as is a unit in an existing attached accessory structure that is not enlarged. An addition that expands the footprint is by right only on a lot of 20,000 sq ft or more under § 260-9M(1)(b), or under the disability-accommodation circumstance in (1)(a). The state definition, repeated in Lincoln's § 260-7, recognizes units in an expanded or remodeled primary dwelling as ADUs.

§ 260-9M(2)(a) copies the state minimums from § 45-24-73(b)(1) as Lincoln's maximums, so the local cap equals the state floor exactly. The town may not bar an ADU from having up to two bedrooms (§ 260-9M(2)(b)[10]). Under § 260-9M(2)(b)[5], dimensional standards for an ADU may not exceed those for an accessory structure in the same district; § 260-28B lets an accessory structure of up to 15 ft in height and 500 sq ft sit within 6 ft of side and rear lot lines, while a larger one must meet the district setbacks (35 ft height limit in the residential districts under § 260-22).

Owner occupancy appears only in the first by-right circumstance, an ADU 'on an owner-occupied property as a reasonable accommodation for family members with disabilities' (§ 260-9M(1)(a)). ADUs under the 20,000 sq ft lot circumstance or the existing-footprint circumstance carry no owner-occupancy requirement in the ordinance, matching § 45-24-73(a). § 260-20A requires an accessory use to be under the same ownership as the principal use, which is a common-ownership rule, not a residency rule, and § 260-9M(2)(b)[12] bars revoking a legal ADU on transfer of title or occupancy. The town's 2019 'Accessory Family Dwelling Unit Affidavit' (family member 62 or older, no rent, permit lapses on transfer) is still posted but conflicts with the current ordinance.

§ 260-9M(2)(b)[8] bars the town from requiring 'more than one off-street parking space per bedroom of the ADU', the state cap in § 45-24-73(b)(2)(viii). The general parking table in § 260-31A still lists 'Residential: 2 spaces for each dwelling unit' with no ADU-specific line, so a one-bedroom ADU's requirement is capped at one space and a studio's is unclear; neither section waives parking entirely.

An ADU that fits one of the three circumstances in § 260-9M(1) is 'allowed by right', and § 45-24-37(e) requires such ADUs to be permitted 'through an administrative building permit process only'. The ordinance creates no special use permit route for other ADUs; the use table marks ADUs 'P' (not 'S') in RA, RS, RL, RG, BL and VCMU, so an ADU outside the circumstances (for example a new detached unit on a 12,000 sq ft RS-12 lot) has no listed path short of variance relief from the Zoning Board of Review. Under § 45-24-73(b)(3) such an application may not be treated as minor or major land development.

State law bars ADUs from being 'offered or rented for tourist or transient use or through a hosting platform' (§ 45-24-73(b)(8)), and Lincoln repeats the bar in § 260-9M(2)(c). The town may not restrict ADU tenants by family relationship or age (§ 260-9M(2)(b)[1]) or require low- or moderate-income occupancy outside inclusionary or comprehensive permit projects ([11]), so long-term rental to anyone is allowed. Lincoln's separate short-term rental registration (Chapter 204, Article II, Ord. 2024-4: annual registration, inspection, $100 per bedroom) does not open ADUs to short stays. A landlord who does not live on the property must also register under the absentee-landlord rules in Chapter 204, Article I.