ADU rules in St. Augustine

St. Augustine regulates ADUs as 'accessory apartments'. The Sec. 28-2 definition expressly includes 'garage apartments', a detached form, so detached units qualify wherever the use is allowed. The use is listed among permitted uses only in RG-1 (Sec. 28-163), RG-2 (Sec. 28-164), RL-1 (Sec. 28-166), and HP-1 (Sec. 28-183); it does not appear in the RS-1 or RS-2 single-family district use lists (Secs. 28-161, 28-162), so allowance depends entirely on the zoning district.

The Sec. 28-2 definition covers a dwelling unit 'contained in an owner-occupied building or premises comprising three (3) or less dwelling units, including garage apartments and single-family type buildings used as apartments and sharing a common entrance', so attached and internal units qualify. Same district limitation as detached: permitted in RG-1, RG-2, RL-1, and HP-1 only; not listed in RS-1 or RS-2.

Sec. 28-2: an accessory apartment is 'a dwelling unit, less than eight hundred (800) square feet or twenty-five (25) percent of the primary dwelling unit, whichever is less'. The cap is part of the definition itself, so a larger unit is simply not an accessory apartment under the code. A separate 'guest house' accessory structure is capped at 500 sq ft, may not have cooking facilities, and is expressly not a dwelling unit.

Owner occupancy is built into the Sec. 28-2 definition: the unit must be 'contained in an owner-occupied building or premises comprising three (3) or less dwelling units'. In HP-1, the parallel single-family use is framed as 'owner occupied or rental dwelling unit', with rentals allowed only on a monthly or longer basis (Sec. 28-183(2)).

The Sec. 28-373(d) minimum-spaces schedule has no accessory apartment line item; under Sec. 28-373(a) an unlisted use provides parking as required of the most closely related listed use, as determined by the planning and building department. The closest listed rates are multifamily residential/apartments (1.5 spaces per 1-bedroom unit, 2 per 2-bedroom unit, 2.25 per unit with 3 or more bedrooms) and single-family/duplex (2 per unit). Sec. 28-367 provides that uses and structures in historic preservation districts 1 through 4 are not required to provide off-street parking or loading.

Where the use is allowed at all, it is allowed by right: 'accessory apartments' appear under 'Permitted uses and structures' in RG-1 (Sec. 28-163(1)(g)), RG-2 (Sec. 28-164(1)(b)), RL-1 (Sec. 28-166(1)(b)), and HP-1 (Sec. 28-183(2)(b)); the use is not listed as a use by exception in any district. A full-text scan of Article III found no other district listing the use, so in RS-1, RS-2, RGO, RGO-A, HP-2 through HP-5, and all nonresidential districts it is simply not an allowed use.

Sec. 28-183(2)(b) permits 'accessory apartments, apartments and duplexes, rental dwellings being rented on a monthly or greater period of time' in HP-1, so anything shorter than monthly is not a permitted use there. Citywide, vacation rentals (defined per F.S. 509.242) are regulated by Ch. 28 Art. III Div. 2 (Secs. 28-145 to 28-156, covering registration, annual inspection, intensity of use, parking, and solid waste), and Sec. 28-158 requires owners of short term rental units in RS-1 and RS-2 (units rented more than four times per calendar year) to register with the planning and building department and prohibits large gatherings of 20 or more people.