Denton County, TX Accessory Structures: ADU Rules (2026)

Accessory dwelling units in Denton County are subject to the zoning ordinances of the specific city or jurisdiction where the property is located. Texas does not have a statewide ADU mandate, though HB 2090 (2023) encouraged municipalities to consider removing barriers to ADU construction. In the City of Denton, ADUs are permitted in certain residential zoning districts subject to conditions including owner occupancy of the primary dwelling, maximum size limits typically capped at 800 to 1,000 square feet or a percentage of the primary dwelling size, and setback requirements. ADUs in Denton must connect to city water and sewer and cannot be sold separately from the primary residence. In Lewisville, ADUs are allowed under specific use permit provisions in single-family zones. Flower Mound allows accessory buildings but has historically been more restrictive on habitable accessory structures. Unincorporated areas of Denton County follow county subdivision regulations, which generally permit accessory structures on parcels meeting minimum lot size requirements but may require septic system approval for habitable units. All ADUs require building permits, must meet residential building code standards, and must comply with applicable fire separation and egress requirements. Parking requirements vary by city but typically require one additional off-street parking space per ADU.