ADU rules in Laramie County

A detached backyard ADU is allowed by right, but only in 5 of the county's 11 base zoning districts and only past real gates. Section 3-1-107(e) makes an ADU 'a permitted use within the URLD, URMD, URHD, MU, and the LU zoning districts', and the definition in 6-1-101 confirms it 'may be an addition to the existing dwelling, be contained within it, or be a detached structure from the principal dwelling', including above a garage. In the rural LU district, which covers most unincorporated land, 3-1-107(e)(ix) bars an ADU on any parcel smaller than two times the AMEC Memo minimum, meaning 10.5 acres against the 5.25-acre base and more inside AMEC zones that require larger lots. In the urban districts (URLD, URMD, URHD, MU) 3-1-107(e)(vii) requires connection to the South Cheyenne Water and Sewer District, so parcels outside that district cannot qualify. This was new law in the 2025 rewrite: the superseded 2022 edition had no accessory dwelling unit at all, only non-rental 'Accessory Living Quarters' for employees or family.

Attached and internal ADUs run through the same section and the same gates as detached ones. Section 3-1-107(e)(iv) and (v) allow an ADU to 'be a new structure, or a portion of it' and to 'be an addition to existing principal dwelling', and 6-1-101 allows one 'contained within' the existing dwelling or inside a renovated garage. The conversion must be a genuinely independent unit: 6-1-101(b) and (c) require a separate means of ingress and egress, a kitchen with a sink with running water and a stove or stove hookup, plus living, sleeping, bathing and bathroom facilities, and warn that 'An independent second kitchen by itself within a principal dwelling does not constitute an accessory dwelling unit.' The same district list, the LU acreage gate, and the urban sewer-district requirement apply, which is why this is conditional rather than a flat yes.

Section 3-1-107(e)(i) sets the headline cap: an ADU 'Shall be no larger in floor area than one-half of the principal dwelling or 1,200 square feet in all Zoning Districts', so the two limits stack and the smaller one governs. Subsection (iii) then says an ADU 'May be the same size as the principal dwelling in the LU Zoning District', which cannot be reconciled with the 'in all Zoning Districts' phrasing of (i); the county's own post-adoption Guidance for Residential Projects resolves it in practice toward the cap, stating flatly that allowable square footage is 50% of the primary dwelling with a maximum of 1,200 square feet. Height and bulk come from the district tables in 3-1-102(h) and (i): accessory structures may reach 35 feet in URLD, 45 feet in URMD, URHD and MU, and 40 feet in LU, and total lot coverage including all structures, parking and impervious surface is capped at 40% in URLD, 50% in URMD, 55% in URHD, 30% in LU and 75% in MU. Ask Planning which reading of (i) versus (iii) applies before designing to the larger LU number.

Section 3-1-107(e)(ii) is one sentence and admits no exception: 'The property owner of record shall be the occupant of the primary residence.' It is written in the present tense as an ongoing condition of the use, not merely a test at application, so the owner of record must live in the principal dwelling while the ADU exists; the ADU is the unit available to a tenant. Wyoming has no statute preempting or limiting local owner-occupancy rules, so nothing at the state level softens this. Note that the county's separate 'Accessory Dwelling Unit Guide' handout omits this requirement entirely, which is one reason that handout should not be relied on.

Section 3-1-107(e)(vi) requires an ADU to 'meet setbacks, parking and maximum lot coverage requirements', and the parking schedule at 3-1-109(cc)(ii) puts ADUs in the single-family category by name: 'Single Family Residential Use: single family, duplex, triplex, manufactured home, accessory dwelling units, accessory living quarters', for which 'One parking space is required.' The same subsection restricts where the space may go: parking 'shall not be located within a public right-of-way unless the roadway is designed for on-street parking and shall not be within a private access easement serving more than one property.' There is no transit-proximity or infill reduction in this code.

An ADU is a by-right permitted use in the five listed districts, with no public hearing and no conditional use permit: 3-1-107(e) calls it 'a permitted use', and ADUs appear in the permitted-use tables for URLD, URMD and URHD at 2-4-101(a), 2-4-102(a) and 2-4-103(a). The approval is a building permit with zoning approval under 3-1-106 and 1-2-100, filed through the county's SmartGov online portal, with plan review quoted at 10 business days in the county's residential guidance. Two prior sign-offs gate the permit: 3-1-107(e)(xii) requires approval from the South Cheyenne Water and Sewer District or the Laramie County Environmental Health Division 'before any building permit is issued', and 3-1-107(e)(viii) requires a septic permit plus well approvals in LU. Since July 1, 2026 the state Fast Track Permits Act also runs a shot clock on these applications, because Laramie County both zones under W.S. 18-5-201 and has adopted the 2024 IRC.

Renting is the point of the use here. The 6-1-101 definition says an ADU 'may be rented out to the public', and the residential-use definitions in Title 6 describe an ADU as 'A single dwelling unit used to provide housing as a rental or for family and friends.' Two structural limits follow the tenancy: the owner of record must occupy the primary residence under 3-1-107(e)(ii), and 3-1-107(e)(xi) requires the ADU to 'be situated on the same lot as the principal dwelling', so there is no separate lot and no separate sale. An ADU is also barred on any lot already holding a duplex, multi-family or other non-single-family use under 6-1-101(e). The LCLUR contains no short-term-rental, vacation-rental or transient-lodging regulation and the county runs no STR licence; the closest lodging use is a Bed and Breakfast, a Class A conditional use in URLD, URHD and LU limited to two guest rooms with the owner living on site, so a dedicated nightly-rental operation may be treated as that separate use rather than as ADU occupancy. Confirm with Planning before marketing an ADU as a short-term rental.