Mesquite | ADUs and Duplexes

Mesquite ADUs and Duplexes: The CUP Path and the D District

An accessory dwelling unit, or ADU, is a small second home on the same lot as a house, such as a garage apartment or a cottage in the back yard. A duplex is one building with two homes that share a wall. Mesquite allows both, under different rules. An ADU needs a Conditional Use Permit from the City Council for each lot, and a duplex needs D or A zoning. This page covers both, the Council's recent ADU decisions, and garage conversions. The Mesquite overview gives the short version.

What Counts as an ADU

The definitions in Sec. 6.102 describe an accessory unit as "An area, in addition to the principal dwelling unit on a lot, which has living, sleeping, and bathroom facilities" and that either "contains a kitchen" or has a main entrance from outside the house. The definition adds "including any such area in a detached structure, whether or not the area contains a kitchen." So a bedroom suite with its own outside door can count as an accessory unit, even with no kitchen.

That matters because of Sec. 2.202(C): "No more than one (1) dwelling unit shall occupy a lot in an AG or R district." The only way the code lets a second living unit onto such a lot is the ADU row of the use schedule in Sec. 2.203. It is marked "C" in the AG and R columns, which means a Conditional Use Permit, and blank in D, TNMR and A. The note says "Requires minimum property area of 21,780 square feet. See Section 2.603.N and definitions."

The Ten ADU Rules

Sec. 2.603(N) says ADUs "may be approved by Conditional Use Permit, in accordance with Section 5.300 , and shall comply with all of the following criteria, unless modified." The words "unless modified" matter most: the Council can change any of the ten rules for one lot when it grants the permit.

Source: Mesquite Zoning Ordinance on municode, Supplement 71, Sec. 2.603(N) and Sec. 2.203.

Three of these rules limit what an ADU can be used for. The ADU "must share utility meter/connections with the primary structure," so it has no separate water or electric account. "The property owner must live on the property." And "The accessory dwelling unit shall not be rented or sold separately." Together they make the Mesquite ADU a home for family or a caregiver, with no rent from it.

The half-acre lot rule is the largest limit. The standard R-3 lot is 7,200 square feet (Sec. 2.302), 33 percent of 21,780 by VanPlex arithmetic, so most Mesquite house lots need the Council to lower the lot size in the permit. The parking rule asks for "a minimum of four (4) off-street parking spaces that are located behind the front and exterior side building lines," arranged so that "four (4) parked vehicles can exit the property without having to move another parked vehicle."

What the Council Has Approved

VanPlex read the City Council items on Legistar from January 2024 to October 5, 2026. Three ADU permits came up, each a zoning change that added a CUP to one lot:

Source: Ordinance No. 5219, Ordinance No. 5267, and the staff reports for files Z0526-0452 and Z0626-0455.

The Buena Vista Street case shows how the Council applies the rules. The owner proposed "to convert an existing detached garage into an ADU for occupancy by her father," a structure of "approximately 439 square feet." The lot is "± 7,840 sq ft / 0.18 acres." Staff found the ADU "generally compatible with the surrounding low-density residential neighborhood" but raised concern about the request to cut parking from four spaces to two, because a car parked in the old driveway "would obstruct the public sidewalk." The Commission voted 7-0 to approve with staff's conditions. On August 17, 2026 the Council passed Ordinance No. 5267 by a vote of 4 to 2, with one member absent. It lowered the lot size to 7,800 square feet and added the stipulation that "The required off-street parking is provided in full."

In the Emerson Drive case, Ordinance No. 5219 describes the lot as being "in the City of Mesquite, Kaufman County, Texas," zoned PD agricultural. The Council item title asked for an ADU 18 feet tall; the signed ordinance allows "a maximum floor area of 1,200 square feet and a maximum height of 17.5 feet." The signed ordinance is the rule that applies. For Antilles Drive, the staff report describes a new detached building of 756 square feet with "449 square feet of living space" and a "307-square-foot garage." Legistar showed no recorded Council vote on it when VanPlex checked on October 9, 2026.

Garage Conversions and Accessory Buildings

Sec. 2.202(E) allows a garage to be "eliminated and converted into additional habitable space located within the primary dwelling unit," with a building permit. The conversion adds rooms to the main house, so it creates no second unit. The garage parking spaces must be relocated "such that the total off-street parking spaces on the lot is not reduced." For lots platted before October 1, 1984, which were never required to have a garage, the Board of Adjustment may approve a special exception with no replacement if at least two staff-approved spaces that are "non-tandem," meaning side by side, stay on the lot.

A detached building that is not a dwelling, such as a workshop or storage building, follows Sec. 2.602:

• No more than 500 square feet in the R and D districts, or 1,000 in AG, and all accessory buildings together may cover no more than 35 percent of the yard they sit in.
• No taller than "fifteen (15) feet, one (1) story, or the height of the principal structure, whichever is less."
• A 5-foot interior side setback, a 3-foot rear setback, and 6 feet of space from other buildings on the lot.
• A "minor building" of 120 square feet or less with walls of 9 feet or less may sit 3 feet from an interior side line (Sec. 2.603(A)).

The Board of Adjustment may approve an "oversize accessory structure" by special exception, though Sec. 2.604(A) warns that "Buildings exceeding 10 percent of the lot area are generally considered to be incompatible." Under Ordinance No. 5274, an accessory storage building permit costs $75 up to 120 square feet and $100 above that.

Duplexes in the D District

The code defines a duplex as "A dwelling unit located in a residential building containing two (2) dwelling units connected by common wall," and adds that "A duplex may be located on one (1) lot or on separate lots." The D district, under Sec. 2.103, provides "small lot single family attached/duplex housing opportunities" on "small, infill tracts adjacent to conventional neighborhoods." The use schedule marks duplexes P in D and in the A districts, and Sec. 2.301(B) makes a duplex in an A district meet the D rules.

• Lot: 12,500 square feet, 75 feet wide and 110 feet deep (Sec. 2.302). Or a pair of lots split along the shared wall, each with half the size and width; "the plat shall indicate which lots are paired" (Sec. 2.304(C)).
• Yards: 25 feet in front, 25 feet in the rear, 5 feet on an interior side and 10 feet on a street side (Sec. 2.302).
• Size: 2,200 square feet of living area for the two homes together, and 1,000 for the smaller one (Sec. 2.302).
• Height: 35 feet or 2.5 stories, whichever is less (Sec. 2.302).
• Parking: four spaces "behind the front building line (two (2) for each dwelling unit)," and on lots platted on or after October 1, 1984, covered parking for two cars per home, in a garage or in a carport with an enclosed storage area of at least 120 cubic feet (Sec. 2.402).
• Walls: on lots in subdivisions with a final plat approved on or after July 1, 2004, at least 90 percent of the exterior walls in masonry (Sec. 2.303), a rule the parking, setbacks and height page compares with state law.

A duplex that does not create a new subdivision needs no site plan (Sec. 2.202(A)). It does need landscaping. Sec. 1A.203(A), as amended by Ordinance No. 5259 in July 2026, asks for turf or ground cover in all yards, "a minimum of one (1) shade tree, or one (1) evergreen tree, or three (3) small ornamental trees in the front yard of each dwelling unit," and shrubs along the front. Sec. 2.301(F) still lists an older version that asks for a shade tree of three-inch caliper and an irrigation system, and it points to Sec. 3.304, which is now reserved. The newer Part 1A text is the one the City amended in 2026; ask the Planning Division which one it applies.

Where a lot is zoned AG or R, a duplex first needs a rezoning, with a $1,500 application fee. Under Ordinance No. 5274, a building permit for "Single-family residential (SFR), duplexes, townhouses, and condominiums" costs $1,100 per unit, and residential plan review adds 25 percent of the permit fee. By VanPlex arithmetic, a duplex is $2,200 in permit fees and $550 in plan review, before trade permits and impact fees.

Where to Go Next

Related on VanPlex: the Mesquite overview, ADUs in Texas, and building codes from duplex to fourplex.

Frequently Asked Questions

Official sources (checked October 2026)