Martin County, FL Accessory Structures: Shed & Carport Rules (2026)

Sec. a permits 'one utility storage structure, incidental to a permitted use' in every zoning district in the county, but limits it to a single structure per lot and caps its floor area at 250 square feet; a second storage building, or one larger than 250 square feet, falls outside this accessory-use allowance and needs its own zoning review, most often as a garage or another listed accessory use with its own size standard. Because the shed is classified as an accessory structure, Sec. A requires it to be ancillary and incidental to the principal residence, located on the same lot (or a contiguous lot under common ownership or an HOA), and in the same zoning district as the house.

Sec. 1 then controls timing: with the narrow exception of fences, walls and boat docks on single-family lots, no accessory structure, including a shed, may be built on a lot before the county has issued all the permits required for the principal use, meaning the shed generally cannot go up ahead of or during construction of the house it serves. Sec. 2 further requires the shed to meet whatever zoning-district standards, such as setbacks, apply to the principal use unless a specific exemption applies. A shed still needs its own building permit from the Martin County Building Division for structural, electrical or plumbing work regardless of its size.