Jacksonville Beach, FL Accessory Structures: ADU Rules (2026)

Section 34-558(a) of the Land Development Code holds the standards for accessory dwelling units, written ADU's in the code. Section 34-300 defines the term as a detached accessory building, or portion thereof, used as an ancillary residential unit on the same lot as the principal single-family dwelling, with a separate kitchen, bathroom, and sleeping area, intended for use by a separate family of occupants.

Where it is allowed: subsection (1) limits ADU's to conditional use approval inside the RM-1 and RM-2 districts. The RM-1 and RM-2 use lists each carry an entry for accessory dwelling units on the same parcel as a single-family dwelling only.

The ten standards: the parcel can contain only one single-family dwelling unit at the time of application, and the minimum lot size is 5,000 square feet. The size line sits under the heading Minimum square footage and reads three hundred fifty (350) to five hundred (500) square feet. Parking is one space for the ADU and two spaces for the existing single-family dwelling, with the garage not counted. The ADU must be compatible in design and materials with the primary structure, cannot exceed 15 feet in height, and must be secured to the ground per the Florida Building Code. The existing residence must be owner occupied, and the owner files a notarized affidavit saying so. One electrical meter and one water meter serve both the house and the ADU.

Timing: a conditional use approval carries a clock. Under section 34-556 the planning commission can set a reasonable time limit for issuing the building permit, and if no permit issues within it the development order becomes null and void. Only one extension of up to one year is available, on a showing of good cause, and the request must reach the planning and development department no later than thirty working days before the order expires. Section 34-557 adds that a conditional use order can be amended, extended, varied or altered only under the current standards and procedures of its original approving body.

An ADU does not ride on the ordinary accessory list. Section 34-716(c), which names greenhouses, garages, sheds, pools and similar structures, expressly says it applies to accessory uses excluding ADU's.