Biloxi, MS Accessory Structures: ADU Rules (2026)

Biloxi's LDO Chapter 23 governs zoning and accessory uses. Article 23-4 sets accessory use standards (Purpose, General Standards and Limitations, and Specific Standards for Certain Accessory Uses), and Article 23-3 sets district-by-district dimensional standards. Detached ADUs are typically capped at 800 sq ft of living area, 20 ft maximum height, and must be located in the rear yard on a permanent foundation; recreational vehicles, travel trailers, and similar movable structures may not be used as permanent dwellings. Side setback for accessory structures is generally 3-5 ft and rear setback typically 5-10 ft depending on the district. No accessory structure may occupy a required front setback area (LDO Section 23-4-4(B)(4)e3). Floodplain elevation rules in Chapter 8 (Flood Damage Prevention) apply on top of zoning standards: in Biloxi most residential lots are in Special Flood Hazard Areas, so an ADU's lowest floor must be elevated to or above Base Flood Elevation plus the city's freeboard (1 ft). Mississippi state law does not preempt or mandate ADUs - Miss. Code Ann. Title 17 grants municipalities zoning authority and Miss. Code Ann. Title 21, Chapter 19 governs building code adoption. Permits are issued by the Biloxi Community Development Department, (228) 435-6280; the LDO is administered alongside the city's adopted building codes.