Fort Bend County, TX Accessory Structures: ADU Rules (2026)

Fort Bend County's Engineering Department confirms on its Building Codes/Zoning page that 'Fort Bend County has not adopted zoning ordinances and does not issue Certificates Of Occupancy.' Counties in Texas operate under limited statutory authority: Local Government Code Chapter 232 governs subdivision platting, Chapter 233 limits county building-code authority largely to flood plains and certain manufactured-home and commercial structures, and Chapter 245 protects vested rights once a permit application is filed. There is no general residential building code or zoning regulation at the Fort Bend County level. The County Engineer does require a Residential Development Permit for the construction of any new structure on residential property, or addition to an existing structure, that meets or exceeds 400 square feet — applications are filed through mgoconnect.org and require a CenterPoint addressing letter (effective January 1, 2022); the application fee is $100. The permit is primarily a drainage, floodplain, and addressing review under the Fort Bend County Regulations of Subdivisions and the Flood Damage Prevention Regulations (signed October 8, 2024) — it is not a zoning or use approval. Whether a homeowner may legally build a guest house, garage apartment, or detached ADU is therefore controlled almost entirely by recorded subdivision deed restrictions and HOA covenants, which most master-planned communities in Fort Bend County strictly enforce. Within incorporated cities, city zoning code applies and supersedes the county framework.