ADU rules in Las Cruces

A detached backyard casita is allowed by right. The Realize Las Cruces Development Code, adopted as Ordinance 3090 with an effective date of February 18, 2025 and amended by Ordinance 3102 on December 1, 2025, classifies an Accessory Dwelling as a self-contained living quarter with its own kitchen that is 'attached or detached to a single-family home located on the same lot' (Sec. 36-3.B, use #19). Figure 36-3-2, the Permitted Use Chart, marks Accessory Dwelling as permitted in NH-1, NH-2 and NH-3, the three Neighborhood districts that carry all of the city's residential zoning across the Rural, Suburban and Urban character areas. One ADU per lot, no hearing, and the unit does not count against the district's maximum residential density. This is a reversal of the repealed 2001 Zoning Code, which defined an ADU as attached and under the same roof as the main dwelling and offered only a kitchenless 'guest dwelling' as a detached option.

The same use classification covers attached and internal units: a garage or basement conversion, an addition, or a unit built under the same roof all qualify as an Accessory Dwelling, subject to the identical seven standards in Sec. 36-3.B #19. The 2001 code's fussy attachment rules are gone; there is no longer any requirement for direct internal access to the main house through a living room or main hallway, no minimum four-foot common wall with a three-foot doorway, and no 'reconversion' obligation. One caution applies to both attached and detached units: the classification ties an Accessory Dwelling to a single-family home on the same lot, and the code does not list it as accessory to a duplex, triplex, quadplex, townhouse or multi-family building.

Standard 4 of Sec. 36-3.B #19 is the headline: 'An Accessory Dwelling Unit shall be limited in size to not more than 50% of the total floor area of the principal dwelling's living space.' There is no flat square-foot ceiling and no separate percentage for attached versus detached units. A detached casita is also an accessory structure, so Figure 36-4-4 applies: maximum combined floor area of all accessory structures is 1,100 sq ft on lots up to 19,999 sq ft or 5% of the lot area on lots of 20,000 sq ft and greater, maximum height is the height of the main building, and main buildings plus accessory structures cannot exceed the district's lot coverage percentage. Ordinance 3102 added that floor-area cap and cut the accessory-structure side and rear setbacks from five feet to three feet. In the Downtown Development Code's GU district a separate limit applies: accessory dwellings there cannot exceed 600 square feet per story.

Nothing in the Development Code requires the owner to live on the property, at application or afterward. The seven ADU standards in Sec. 36-3.B #19 impose no residency test, and standard 5 expressly allows the unit to be rented. This is the single biggest change from the repealed 2001 Zoning Code, whose Sec. 38-53 required that the 'Owner of record shall reside in either the main or accessory dwelling unit for a minimum of six months of each calendar year' and voided the use on a change of ownership. Standard 2 caps occupancy at one family unit at a time, but Sec. 34-5 defines Family as 'Persons related by blood or marriage, or a group of persons who need not be related by blood or marriage, living together as a single housekeeping unit,' so that is a single-household limit, not a relatedness requirement. The old family-only rule (ADUs 'created solely to accommodate those related to the family') was repealed with the rest of the 2001 code.

The Accessory Dwelling row of Figure 36-3-2 lists 'N/A' under both Min. Vehicle Parking and Min. Bicycle Parking, so no additional off-street space is required for the unit. The 2001 code charged an ADU one auto parking stall per unit. Off-street parking is separately not required at all in the Urban Character Area, the MXCO Mixed Use Corridor Overlay, the TCO Town Center Overlay, the NCO Neighborhood Center Overlay and the Downtown Development Code area. One practical exception: if the casita is operated as a registered short-term rental, LCMC Sec. 16-508(f) requires the operator to provide onsite off-street parking through a garage, parking shelter or driveway, or else to advise renters of parking locations that do not burden neighbors.

Accessory Dwelling carries the filled-circle 'Use is permitted in district indicated' symbol in NH-1, NH-2 and NH-3, so no Special Use Permit and no Planning and Zoning Commission hearing is involved. Review is administrative: a Site Plan is required for any building that needs a building permit and is approved by the Community Development Director alone when no Special Use Permit is attached (Sec. 36-5.B.4.a), and the Building Official issues the building permit and certificate of occupancy (Sec. 36-5.E). Las Cruces runs its own building department and permit portal, so both zoning and building approval are local; the state Construction Industries Division is not involved. Sec. 36-4.B.2.d) withdraws the usual small-structure exemption when a structure will be used as an Accessory Dwelling, so even a unit under 120 square feet needs a permit. A zoning variance can waive dimensional standards only and cannot be used to modify permitted uses or use-based standards (Sec. 36-5.F.1.b).

Standard 5 of Sec. 36-3.B #19 says plainly that 'Accessory Dwelling Units may be rented or occupied by a guest,' and standards 6 and 7 let the unit have its own utility meter and require it to carry an assigned address. There is no separate-sale path: the ADU stays on the same lot as the single-family home. Short-term rentals, meaning any rental period no longer than three continuous months, are regulated citywide by LCMC Chapter 16, Article XII (Ordinance 3103, adopted December 15, 2025), effective January 1, 2026 with enforcement beginning July 1, 2026. An operator must obtain a Community Development business registration ($35 a year), register each unit with Visit Las Cruces ($50 once plus $35 a year), carry at least $500,000 of liability insurance, provide onsite off-street parking or renter parking guidance, post the registration inside the unit, keep overnight occupancy to two people per bed plus two per unit, and mail notice to every property owner within 500 feet within ten days of applying. Lodgers' tax applies. There is no owner-occupancy or primary-residence test and no citywide cap on the number of short-term rentals.