ADU rules in Santa Fe

Detached accessory dwelling units are an allowed accessory use in the RR, R-1 through R-6, R-7 through R-9, R-7-I, RC-5, RC-8, R-10 through R-29, MHP, RAC, MU, BCD, C-1, C-2, C-4, I-1, I-2, BIP and HZ districts. A detached ADU may be up to 26 feet tall, the same maximum as a residential building in the district, and must meet the setbacks that apply to accessory structures. The rear setback may drop to 5 feet if the ADU is 14 feet or less in height and stands at least 10 feet from the principal structure. A tiny home may be used as an ADU, but mobile homes and recreational vehicles may not (a structure meeting the manufactured home definition is allowed).

An ADU created within or attached to the principal structure is allowed and must stay within the building envelope of the principal structure. The code definition confirms both forms: an accessory dwelling unit is a dwelling on the same lot as, and subordinate to, the primary dwelling, and it may be within the same structure or detached.

The ADU shall not exceed either the gross floor area of the principal dwelling unit or 1,500 square feet, whichever is less, and shall be no taller than 26 feet. The 26-foot cap is new with the 2026 code rewrite and replaces the older rule that held ADUs to the lower height limits for accessory structures.

No owner occupancy is required to build an ADU or to rent it long term: the property owner may rent the principal dwelling and/or the ADU for periods of not less than 30 days. Owner occupancy is required only if one of the two units is to be used as a short-term rental, in which case the owner-occupant must live in the other unit.

Table 7-4 sets the rate for an accessory dwelling unit at one space per unit if the ADU is less than 1,000 square feet, otherwise two spaces per unit. The requirement may be met with on-street parking: a legal on-street space abutting the property counts as one required off-street space if the street has no residential parking permit restrictions, measures at least 35 feet from face of curb to face of curb, and has no posted restrictions prohibiting on-street parking. Each on-street space may be counted only once per abutting lot, and credited spaces must stay available to the general public and cannot be reserved or signed for the property's occupants.

ADUs are permitted by right as an accessory use: Table 5-1 marks the accessory dwelling unit row with an 'A' in every district where they are allowed, and the code states that an 'A' means the use category is permitted as an accessory use. No district requires conditional use approval for an ADU. A construction permit from the Planning and Land Use Director or building official is still required, along with the use-specific standards of 14-5.3(C)(2).

The property owner may rent the principal dwelling and/or the ADU for periods of not less than 30 days with no occupancy requirement. Alternatively an owner-occupant may short-term rent either the principal dwelling or the ADU, but not both, under the short-term rental standards at 14-5.3(C)(12), while occupying the other unit. A short-term rental needs a city business license and a city-issued STR permit, with an initial inspection, annual renewal and mailed notice to neighbors and any homeowners association. ADU-compliant short-term rentals are exempt from the 50-foot spacing rule that otherwise blocks a new permit near an existing one, but two citywide limits still apply: the city issues at most 1,000 STR permits in total (a waiting list opens once the cap is reached) and no more than one permit per natural person. A permitted STR cannot be rented more than once in any seven-day period, except for rentals beginning between November 15 and January 15.