ADUs in Texas: Rules, Costs, and Whether Your Lot Qualifies
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An accessory dwelling unit in Texas is a second, self-contained home on a single-family lot with its own kitchen, bathroom, and entrance. Whether you can build one is decided by city zoning and your HOA, not state law. In North Texas, a detached ADU typically costs $150,000 to $300,000.
What counts as an ADU — and what does not
An ADU has to be independently livable: sleeping space, a full bathroom, a kitchen, and its own entrance. That definition matters, because the kitchen is usually what turns a permitted “bonus room” or “pool house” into a regulated second dwelling unit. A guest suite with a wet bar is a room. Add a range and it becomes a dwelling.
ADUs come in three shapes in North Texas: detached (a small standalone structure or a casita in the backyard), attached (a suite added onto the house with its own exterior door), and conversion (a garage, shop, or above-garage space finished out as living space).
Texas has no statewide ADU rule — your city does
There is no single Texas law that permits or prohibits ADUs. Every decision is local: whether a second dwelling is allowed in your zoning district, minimum lot size, maximum ADU square footage, required setbacks, height limits, parking requirements, and whether the unit may be rented. Two houses three miles apart can have completely different answers.
Then there is the HOA. In much of North Texas the deed restrictions are stricter than the city code, and an HOA can prohibit a second dwelling on a lot the city would happily permit. That is the first thing to check, because it is the cheapest thing to check.
What an ADU costs in North Texas
| Type | Typical Cost | Typical Size |
|---|---|---|
| Garage conversion ADU | $75,000–$140,000 | 350–550 sq ft |
| Attached ADU / in-law suite | $120,000–$220,000 | 400–700 sq ft |
| Detached ADU / casita | $150,000–$300,000+ | 500–900 sq ft |
Detached costs more per square foot because it is a complete small house: its own foundation, roof, exterior envelope, HVAC system, and utility runs from the main house or the street. These are typical North Texas ranges, not a quote.
The questions to answer before you design anything
In order: Does the HOA allow it? Does zoning allow a second dwelling on this lot? What is the maximum size and where can it sit after setbacks? Can water, sewer, gas, and electrical service reach it, and does the existing panel and sewer line have capacity? Only after those five answers does floor plan work make sense. Designing first and checking later is the most expensive sequence available.
Planning a project? See our additions and new construction page for scope, process, and recent work.
Frequently Asked Questions
Are ADUs legal in Texas?
There is no statewide ban and no statewide right. Legality is set by city zoning and, separately, by your HOA’s deed restrictions. Some North Texas cities permit ADUs by right in certain districts; others require a special use permit or prohibit them entirely.
Can I rent out an ADU?
That depends on local rules. Some cities allow long-term rental but restrict short-term rental; others require the owner to occupy one of the two units. Rental intent should be confirmed with the city before construction, not after.
Does an ADU need its own utility meter?
Not always. Many North Texas ADUs run off the main house’s service, which is simpler and cheaper, but requires confirming the existing panel and sewer capacity. Separate meters are usually driven by rental plans or by utility provider requirements.
Is a casita the same as an ADU?
In practice, yes — casita is the regional term for a small detached guest house. Whether it is regulated as an ADU depends on whether it contains a kitchen and functions as an independent dwelling.
Will an ADU raise my property taxes?
Yes. New conditioned square footage is added to the appraised improvement value. The increase depends on the size and finish level of the unit and the county appraisal district’s assessment.
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