ADU rules in Key West

The SF (single-family residential) district accommodates one accessory attached or detached unit per principal dwelling unit, but only if the unit wins a building permit allocation under the BPAS growth cap and meets the affordability and occupancy criteria of Sec. 122-233. No other residential district (LDR-C, MDR, MDR-1, MDR-C, HDR, HDR-1) lists accessory units; a separate accessory unit infill program covers mixed use and commercial districts.

Same authorization as detached: one accessory attached or detached unit per principal dwelling in the SF district, subject to BPAS allocation and the Sec. 122-233 criteria. Under the BPAS definitions, an accessory unit cannot take up more than 40 percent of the principal structure.

The size band appears identically in Sec. 122-233(a)(10), the Sec. 86-9 definition, and the Sec. 108-986 BPAS definition. Accessory units are exempt from lot coverage, impervious surface (if stormwater is contained on site as certified by a licensed engineer), and landscaping requirements, and must keep a minimum 5-foot rear and side setback. The Comprehensive Plan's Policy 1-1.1.7 still says a variance-approved two-bedroom unit may reach 700 square feet, but the land development regulations that govern the permit (Secs. 122-234 and 108-986) cap it at 600.

The zoning sections (122-232 to 122-234) impose no ongoing owner-occupancy rule, but the BPAS definition requires that when an accessory unit occupancy permit is originally initiated, the principal unit must be owned and occupied by a permanent resident. The accessory unit itself must be occupied by permanent residents as a primary residence. The Comprehensive Plan's Policy 1-1.1.7 adds that the owner-occupancy condition does not apply while the principal unit is under construction; the code section does not repeat that exception.

Sec. 122-233(a)(8): 'There shall be no additional parking requirement for the Accessory unit.' In the separate mixed-use accessory unit infill program, applicants may provide two bicycle or scooter parking spaces per unit as an alternative to seeking parking variances.

Accessory residential units are listed among the permitted uses of the SF district (Sec. 122-235(1)), and the Sec. 86-9 definition says one accessory dwelling unit is allowed as of right there, so no conditional use approval is needed. However, every unit must first win a building permit allocation under the BPAS growth cap (counted as 0.78 dwelling unit), and a second bedroom requires a planning board variance. Accessory unit BPAS applications can be received at any time during the allocation year if they meet the prior year's average application score; otherwise they wait for the annual ranked cycle. The city's 2026 BPAS Annual Report shows staff awarding such an allocation administratively, without planning board action.

The rent cap and perpetual recording are in Sec. 122-233(a)(1) and (b); the no-transient-rental and no-condo-sale rules are in the Sec. 86-9 accessory unit definition and Sec. 122-233(a)(3). Sec. 86-9 treats any rental of a residential dwelling for less than 28 days as a transient living accommodation, and Sec. 122-1371 (adopted 2002, before the 2011 cutoff in the state vacation rental preemption) bars transient use of residences without a city transient license, which an accessory unit cannot receive.