ADU rules in Fort Worth, TX — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Yes — you need a building permit for any accessory dwelling unit in Fort Worth, whether it is a detached ADU, an attached ADU, or a garage conversion. Fort Worth regulates ADUs as 'Accessory Uses on Residential Lots' under §5.301 of the Zoning Ordinance (Appendix A to the City Code). In one-family ('A' through 'AR') districts, an ADU is permitted as an accessory dwelling but cannot be operated as a separate, independent residence. ADUs must observe the side and rear setbacks of the underlying zoning district and may not exceed the height of the primary residence.
Fort Worth Zoning Ordinance §5.301 (Accessory Uses on Residential Lots) is the controlling section for ADUs — sometimes called 'granny flats,' 'casitas,' 'secondary dwellings,' or 'accessory apartments.' Key rules:
DETACHED ADU vs. ATTACHED ADU: A detached ADU is a stand-alone structure on the same lot as the primary single-family home. An attached ADU shares at least one wall (or is built above an attached garage). Both types are treated as accessory buildings under §5.301. Detached ADUs are limited to one story plus an unheated attic or loft, and cannot exceed the height of the primary residence. Attached ADUs follow the height limits of the underlying zoning district.
LOT COVERAGE & SETBACKS: All accessory buildings, including ADUs, must observe the side and rear setbacks of the district applicable to the primary residential use. The total rooftop area of all structures on the lot may not exceed the district's maximum lot coverage (typically 40% in 'A-5' and 'A-7.5' One-Family districts).
ONE-FAMILY DISTRICT RESTRICTION: In one-family districts (A-43, A-21, A-10, A-7.5, A-5, AR), §5.301 expressly states that an ADU may not be used as a separate, independent residence. This means you may not rent the ADU to an unrelated tenant on a separate lease; the ADU is meant for household members, guests, or domestic help. In two-family ('B') and multi-family districts under §4.707 and following, separate dwelling units are permitted.
PARKING: Fort Worth generally requires one additional off-street parking space for a habitable accessory unit, on top of the two off-street spaces required for the primary single-family dwelling under §6.201.
PERMITS: A building permit is required from Fort Worth Development Services (Building Permits) before any ADU construction or garage conversion. Plans must show foundation, setbacks, height, and compliance with the International Residential Code as adopted by Fort Worth. Plumbing, electrical, and mechanical permits are also required.
TEXAS SB 840 (Effective September 1, 2025): SB 840 limits a Texas city's ability to require more than one parking space per dwelling unit for qualifying mixed-use or multifamily projects on commercial-zoned sites. SB 840 does not preempt the §5.301 one-family-district restriction or change ADU rules for single-family lots.
Operating an ADU as a separate independent residence in a one-family district violates §5.301 and is enforced by Fort Worth Code Compliance with notices of violation, daily-accruing fines, and potential Building Standards Commission action. Constructing an ADU without a building permit triggers stop-work orders under Fort Worth Building Law and after-the-fact permit fees. Unpermitted ADUs discovered at sale time can delay closing and require costly retrofitting.
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Side-by-side rule comparisons with other cities in Tarrant County.
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