ADU rules in Livingston

Livingston replaced its entire zoning chapter effective January 1, 2026 (Ordinance 3064, adopted December 2, 2025), and the new Chapter 30 allows one ADU by right for each single-family dwelling on a lot. Table 30.40-1 marks 'Accessory Dwelling Unit (ADU)' as A (Allowed by Right) in the four districts where houses are built (R1 Low Density Residential, R2 Medium Density Residential, LMU Light Mixed Use, HMU High Density Residential-Mixed Use); in CBD, GC, LI, I, and PC a new ADU is allowed only where a single-family residential use already exists on the parcel. Detached units qualify alongside attached and internal ones, and the old rule that a detached ADU sit behind the primary dwelling (former sec. 30.43(B), Ord. 3056 of 12-17-2024) was dropped in the rewrite; an ADU now simply meets the same district setbacks and height as the house. This mirrors MCA 76-2-345 (SB 528, 2023), which requires every Montana municipality to allow at least one ADU by right on any single-family lot.

Attached and internal ADUs are the same by-right use as detached ones: the code defines an accessory dwelling unit simply as 'an independent dwelling unit which is accessory to a primary dwelling unit on the same lot', and sec. 30.43(D) expressly contemplates 'ADUs that are entirely contained within the primary dwelling, such as a basement ADU'. Internal conversions get a bonus: they are exempt from the size cap that applies to detached and attached units. One ADU is allowed per single-family dwelling on the lot; ADUs do not attach to duplexes or multifamily buildings (sec. 30.43(B)).

Sec. 30.43(D) adopts the state-law ceiling verbatim: an ADU 'shall not exceed 75% of the gross floor area of the primary dwelling or 1,000 square feet, whichever is less', matching MCA 76-2-345(1)(c), while exempting units wholly contained within the existing house from any size limit (a more permissive local choice that 76-2-345(8) allows). There is no ADU-specific height or setback rule; the district standards that govern the house govern the ADU (R1 and R2: 30 ft maximum height, or 36 ft with a roof pitch of at least 3:12, measured from pre-disturbance grade; Table 30.41.1-1).

Neither the ADU section nor any other part of the post-2026 zoning code requires the owner to live in either unit, and state law forbids such a rule: MCA 76-2-345(2)(c) provides a municipality 'may not require that the single-family dwelling or the accessory dwelling unit be occupied by the owner'. Owner occupancy matters in Livingston only for classifying a short-term rental: an owner-occupied STR is Type 1 and a non-owner-occupied STR is Type 2, with Type 2 carrying an extra local-contact requirement (sec. 30.20.3 definition; sec. 30.57(D)).

Sec. 30.43(F) states 'No additional off-street parking shall be required for an ADU', and the parking minimums table lists 'Accessory Dwelling Unit: None' (Table 30.51-2). That tracks MCA 76-2-345(2)(a), which bars ADU parking mandates and fees in lieu statewide. One carve-out: operating the ADU as a short-term rental invokes the STR use's own standard of one space per unit (Table 30.51-2), which the Zoning Administrator may waive where site constraints prevent on-site parking; STR regulation is expressly preserved by 76-2-345(3).

ADUs are 'A = Allowed by Right' in Table 30.40-1: no public hearing, special exception, or conditional use permit, consistent with the by-right definition in MCA 76-2-345(9)(b). Construction needs a standard building permit from the Building Official, and Site Plan Review does not apply (sec. 30.46(A) triggers it only at ten or more dwelling units, 10,000 plus sq ft of commercial floor area, or twenty or more parking spaces). The February 2026 city fee schedule lists no separate ADU planning fee, so normal building permit fees apply (the statute caps any ADU application fee at $250). In the Downtown Historic Overlay, exterior work may receive Historic Preservation Commission design review, but the code makes that review advisory and non-binding: recommendations 'shall not delay or prohibit permitting decisions' (sec. 30.44.1(E)).

Nothing in the code restricts renting an ADU on ordinary leases, and with no owner-occupancy rule the whole property can be tenant-occupied. Short-term rentals became a regulated use in the January 2026 code: every STR operator must obtain a city permit before operating, renew it annually with a fee, and pass a basic safety inspection (smoke detectors, fire extinguishers, adequate egress) by the Building Official or Fire Marshal (sec. 30.57(C), (E)). STRs of both types are allowed uses in R1, R2, LMU, HMU, CBD, and GC and not allowed in LI, I, and PC (Table 30.40-1); a non-owner-occupied Type 2 STR must designate a contact within a 50-mile radius (sec. 30.57(D)), and an STR unit needs one parking space (waivable for site constraints). An ADU cannot be sold off separately: sec. 30.43(H) says if it is subdivided from the primary dwelling it stops being an ADU and must meet the district's full density requirements. As of 2026-08-04 the city had not yet posted an STR permit application or an STR fee line in its February 2026 fee schedule; expect implementation details to follow.