ADU rules in Rio Rancho

Rio Rancho lists “Accessory dwelling unit” as a permissive (by right) use in every residential district except M-H: E-1 §154.05(B)(18), R-1 §154.08(B)(16), R-2 §154.09(B)(16), R-3 §154.10(B)(18), R-4 §154.11(B)(16), R-5 §154.12(B)(16) and R-6 §154.13(B)(20). The residential land use table at §154.19 marks the use P in all seven of those columns and leaves the M-H column blank, which the table legend reads as not permitted. The A-R Agricultural Residential District separately allows an “accessory dwelling unit or accessory living space” as an incidental structure (§154.36(B)(2)). The gate that actually bites is lot area: an ADU is only an ADU if it sits on a lot of 7,000 square feet or greater, and it may not be a mobile home. ADUs entered the code with Ord. 21-15 in 2021, and Ord. 22-20 later reworked the §154.70 accessory-building standards that carry the ADU rules.

The definition is explicit that an accessory dwelling unit may be “attached or detached,” so an addition, a converted garage or an internal suite counts as an ADU provided it is a separate complete housekeeping unit with its own entrance, kitchen, sleeping area and full bathroom. The district permissive-use lists and §154.19 draw no distinction between attached and detached units, and the same 900 sq ft / 50% cap, 7,000 sq ft lot floor and extra parking space apply either way. One trap: each residential district also lists “Second kitchen” as its own permissive use, and provides that a second kitchen “may be located within the primary residence or accessory dwelling unit, but not both,” so a property cannot have an ADU kitchen and a separate second kitchen in the main house. §154.70(A) is drafted around accessory buildings and structures, so an attached or internal unit is judged against the same design standards even though it shares walls with the house.

Both the §154.03 definition and the standards at §154.70(A)(6) cap an ADU at 900 square feet or 50% of the primary structure, whichever is greater, so a larger house buys a larger casita: a 2,400 sq ft home supports a 1,200 sq ft unit, while any house under 1,800 sq ft still gets the flat 900 sq ft floor. The unit must be on a lot of 7,000 square feet or greater. Height comes from §154.70(A)(1): accessory buildings and dwelling units may not exceed the height of the primary structure or 24 feet, whichever is greater. A second, cumulative ceiling in §154.70(A)(3) limits all accessory buildings on the lot together to 75% of the size of the primary house or 15% of the lot area, whichever is greater. The zoning code sets no minimum ADU size.

Chapter 154 imposes no residency condition on either dwelling. The complete list of ADU standards in §154.70(A)(6) covers only size, lot area and parking, the district permissive-use lists attach no occupancy condition, and the zoning chapter contains no “owner-occupied,” “owner occupancy” or “principal residence” language anywhere. New Mexico has no statewide ADU statute that speaks to owner occupancy either way, so this is purely a local choice. The nearest thing to a residency rule sits in the short-term rental chapter: §123.05(C) requires a short-term rental permit to be held by a natural person and caps each person at two permits, but it does not require that person to live on the property.

The §154.03 definition and §154.70(A)(6) both require one additional parking space for an accessory dwelling unit, and both add the same qualifier: the space must not block a two-car garage, so stacking a car in the driveway in front of the garage doors does not satisfy it. That space is on top of what the house itself owes under §154.76(A)(1): 2 spaces with 1 enclosed for a studio or one-bedroom, 3 spaces with 2 enclosed for two bedrooms, and 4 spaces with 2 enclosed for three or more bedrooms. §154.76 has no ADU line item of its own and offers no transit, small-lot or affordability reduction. A standard space is 9 feet by 18 feet under §154.76(D)(3).

The residential land use table at §154.19 marks “Accessory dwelling unit” P under a legend reading “P = PERMITTED, CU = CONDITIONAL USE, BLANK = NOT PERMITTED,” and every residential district section lists ADUs under “Permissive uses” rather than “Conditional uses (requiring use permit),” so no Planning and Zoning Board hearing is involved. What the project needs is construction approval: §154.81 requires a building permit, §154.82 requires a certificate of occupancy, and the city's own Building Inspection Division issues the permit (Rio Rancho does not rely on the state Construction Industries Division for building permits inside the city), with submittal through Click2Gov and a plan review fee of 65% of the building permit fee. The Planning and Zoning Division's published list of land use application forms contains no ADU application, which is consistent with the by-right treatment.

Nothing in Chapter 154 limits who may occupy an ADU, bars renting it or sets a minimum lease term, and there is no owner-occupancy rule, so a long-term tenancy is unrestricted. Stays of less than 30 days are a separate regulated use: Chapter 123, adopted as Ord. 24-22 on 10-10-2024 with effect 7-1-2025 and amended by Ord. 25-01, requires a short-term rental permit from the Department of Development Services for all or part of any dwelling unit rented for under 30 days. Short-term rentals are allowed only in E-1 and R-1 through R-5, never in R-6; citywide permits are capped at 1% of Rio Rancho's total housing units per the latest American Community Survey; no permit issues within a 100-foot radius of an already-permitted unit; permits go to natural persons only, two apiece, and do not transfer with a sale. A permitted unit may not be rented more than six separate times in a calendar month, a cap that lifts every October. Costs are a $100 application plus a $300 annual permit fee, with a required inspection, $250,000 of short-term rental insurance, a city business registration, lodgers' and gross receipts tax, and a local operator reachable within one hour. The code provides no way to sell an ADU separately from the house; both sit on one lot, and any condominium route would first need the zoning certification §154.79 requires before a declaration can be recorded.