ADU rules in Southlake

Southlake has no independent detached ADU. What it allows is one detached 'domestic employee or family quarters' (sleeping, cooking, and sanitation) built as part of a detached residential garage, and only in the large-lot districts AG, RE-5, RE-7, SF-1A, SF-1B, and SF-2. Occupancy is limited to on-premises domestic employees or family members of the owner, and the quarters may never be rented or used as a separate domicile. In SF-30, SF-20A, and SF-20B a detached quarters is not authorized; only attached or internal quarters are.

One attached or internal domestic employee or family quarters is a by-right accessory use across essentially all single-family districts (AG, RE-5, RE-7, RCS, SF-1A, SF-1B, SF-2, SF-30, SF-20A, SF-20B, plus approved single-family uses in R-PUD, EC, and DT). The quarters must be attached to or internal within the principal dwelling, must remain accessory and subordinate to the single-family use, and cannot be rented or occupied as a separate domicile; only one quarters is allowed per residence. This is a restricted in-law or staff suite, not an independent second unit.

Accessory buildings generally max out at one story or 14 ft under §34.2(e), though district standards can allow more (SF-1A allows 20 ft for accessory structures of 500 sq ft or more, and §34.1(kk) contemplates quarters above a garage's first floor). Cumulative accessory building area differs sharply by district: 3 percent of lot area or 4,000 sq ft in SF-1A, 750 sq ft total in SF-30, 600 sq ft total in SF-20A.

No clause expressly orders the owner to live in the main house, but quarters occupancy is defined entirely relative to the owner: occupants must be domestic employees working on the premises or family members of the owner of the premises, and the quarters can never be rented or used as a separate domicile. That occupant restriction effectively ties the quarters to the owner's household; it cannot function as a unit independent of it.

Section 35 sets the single-family standard at two spaces per dwelling unit not counting garage spaces. Because a quarters is part of the principal residential unit rather than a separate dwelling unit, the schedule assigns it no additional spaces. Additional parking is triggered only where a change or enlargement creates a need for a 10 percent or greater increase in spaces.

Where authorized, domestic employee or family quarters are by-right accessory uses under Section 34; the Section 45 specific use permit list contains no SUP requirement for quarters in residential districts (its only caretaker-unit SUP, item 27, applies to the nonresidential B-2 and I-1 districts). Construction takes a standard building permit: the city requires permits for detached accessory structures over 120 sq ft and any attached structure, with engineered plans and plan review under the 2021 IRC as amended.

Southlake forecloses both long-term and short-term rental of accessory quarters. The zoning ordinance bars any rental or separate-domicile use of a quarters, so it cannot generate rental income even from long-term tenants. On top of that, City Code chapter 11, article VI (Ord. No. 1187, adopted February 6, 2018, still codified through Supp. 34) bans every short-term rental of any residence or portion of one citywide.