St. Johns County, FL Accessory Structures: ADU Rules (2026)

St. 2 as a permitted accessory use in residential districts. To qualify, the structure must be a separate building that is accessory in both use and size to the main residence, and it must be intended only for intermittent or temporary occupancy by a non-paying guest or family member, never a paying tenant. The code allows limited cooking equipment, capped at a microwave oven, a bar sink and a refrigerator/freezer under 10 cubic feet, which keeps the unit well short of a full kitchen. Occupancy by the same person is capped at thirty days within a calendar year; stay longer and the structure risks reclassification.

Provided those conditions hold, the Guest House is not treated as a separate Dwelling Unit for zoning-density purposes, meaning it does not need to satisfy a second unit's own lot area or utility connection requirements. It must still meet the same required front, side and rear yard setbacks that apply to the principal residential building on the lot, so placement is not unrestricted just because the structure is smaller. Homeowners planning a garage apartment or in-law suite in unincorporated St. Johns County should confirm with Growth Management's Building Services that the kitchen equipment and intended use fit within these limits before pulling a building permit, since exceeding the kitchen or occupancy thresholds converts the structure into a second dwelling requiring separate zoning approval.