ADU rules in Grand Prairie

Grand Prairie prohibits using an accessory structure as a separate dwelling unit on any lot that has a home on it, so a backyard cottage or garage apartment with its own kitchen is not allowed on a single-family lot. The UDC's Accessory Apartment definition nominally mentions units in a separate accessory structure, but that definition routes second units through the 2-Family/Duplex use classification, which is not permitted in any single-family detached district (SF-E through SF-6, SF-ZLL). There is no accessory-dwelling row in the use charts and no Specific Use Permit pathway for one.

An accessory apartment built in or added to the main house makes the lot a two-dwelling-unit property, and the definition expressly points to the 2-Family/Duplex row of the use charts. That use is permitted by right only in the SF-A (Single Family Attached) and 2F (Two Family) districts and is blank (not permitted) in every single-family detached district. Where allowed, the unit must meet all eight accessory-apartment criteria including minimum size, a two-bedroom cap, owner occupancy, and no street-facing evidence of the unit other than an entrance.

The size test is relative to the existing house. Detached accessory buildings generally are also subject to the UDC Article 6 dimensional caps, but those govern non-dwelling structures since a detached second dwelling is prohibited.

The property owner must live in one of the two units; owner occupancy of either the main home or the accessory apartment is a listed criterion of the use. The unit must also have well-marked entrances for emergency and mail service and certified adequate water and sewer service.

Parking scales with occupants rather than a flat per-unit count. If the unit is ever used as a short-term rental, a separate rule limits total vehicles to the available off-street spaces and bars STR occupants from parking on nearby residential streets.

There is no Specific Use Permit category for accessory apartments: in the two base districts where a second unit can exist (SF-A and 2F, via the 2-Family/Duplex classification) it is a by-right use needing only standard building permits, and in all other base districts it is simply not permitted. A large share of the city sits in Planned Development districts whose case-by-case use lists override the base chart. Garage conversions into living space of the main home (not a separate unit) are permitted across all single-family districts.

The STR regime (Ord. 11207-2022, amended through Ord. 11836-2026) requires a Code Compliance permit for each rentable unit, annual renewal, neighbor notice, hotel occupancy tax, and a required guest brochure. The use chart lists Short-Term Residential Rental with no district symbols and the annotation Permit Required, so STR permission comes from the Chapter 29 permit system rather than district-by-district zoning.