A detached ADU or casita in DFW typically costs $150,000 to $400,000+ for a ground-up build, or roughly $250 to $400 per finished square foot. Converting an existing garage shell costs far less because the structure already stands. Your final price hinges on size, finish level, and whether your city allows a separate dwelling on the lot.

§ 01What exactly is an ADU or casita, and how is it different from a room addition?

An ADU (accessory dwelling unit) or casita is a second, self-contained living space on your property: its own kitchen or kitchenette, full bathroom, sleeping area, and a private entrance. It can sit detached in the backyard, perch above or beside a garage, or be carved out of existing square footage. That independence is what separates it from a standard room addition. If you only need more square footage tied into the main house, it is usually better to explore our room addition services instead. An ADU is its own small home, which is exactly why it costs more per square foot than a typical bump-out.

A finished detached backyard casita — a full second dwelling in a Dallas–Fort Worth backyard.

§ 02How much does a backyard casita or detached ADU cost in DFW in 2026?

Because a detached ADU is essentially a small house, its budget overlaps the DFW addition range of roughly $120,000 to $400,000. Expect about $250 to $400 per finished square foot once you add a full kitchen, bathroom, HVAC, and separate utility runs. A converted garage shell is the value play: the foundation, walls, and roof already exist, so you pay mainly to insulate, plumb, wire, and finish it. For a deeper breakdown of how these projects are priced in this market, see our DFW Remodeling Cost Study 2026 and the full 2026 DFW addition cost ranges.

If a freestanding structure fits your goals, our detached garage and structure builders handle the foundation and shell, and our garage conversion cost guide walks through turning an existing garage into livable space at a lower price point.

An ADU is the only addition that comes with its own front door, so the real cost question is never just square footage. It is whether your city lets you put a second home on the lot, and that answer should come before the first design sketch.— May N. · Co-Founder, UHS Remodeling

§ 03What are the three DFW use cases that justify an ADU?

Rental income. A legally permitted ADU can generate long-term rental income and may add resale value, since it appeals to buyers who want flexible space. Confirm rental rules with your city and HOA first, and treat the income as a long-term return rather than a quick payback. Aging parent. A single-level casita with a curbless shower, wider doorways, and a zero-step entry lets a parent live close by while keeping privacy and independence. Adult child or home office. A detached studio gives a returning adult child a real front door, or becomes a quiet workspace separated from the main house. Each use case reshapes the floor plan, so we design around your goal from day one.

A garage-with-ADU-above keeps the build on a single footprint.

§ 04Which DFW cities allow ADUs, and what are the rules?

This is the make-or-break question, and the honest answer is that it varies city by city across DFW. Some communities permit detached ADUs by right, some allow them only with a special exception or on larger lots, and some restrict or prohibit a second kitchen on a single-family lot. Before you design, verify these common rules: lot-size minimums, rear and side setbacks, maximum ADU square footage relative to the main house, height limits, separate water and sewer tap requirements, off-street parking, and whether short-term or long-term rentals are allowed. HOA covenants can be stricter than the city. We have built additions across communities like Frisco home additions and McKinney home additions, so we start every ADU project by checking your specific jurisdiction and HOA before anyone signs off on a plan.

§ 05How long does a DFW ADU build take, and what does the process look like?

A ground-up detached casita takes longer than an interior remodel because it adds a foundation, framing, and separate inspections. A realistic timeline runs about four to seven months from signed design to final inspection, depending on city permitting speed and weather. The path is: feasibility and zoning check, design and fixed-price proposal, permit submittal, foundation and shell, rough-ins and inspections, interior finish, and final sign-off. A garage conversion compresses this considerably since the structure already stands. As a Plano-based DFW design-build team, UHS keeps design, permitting, and construction under one roof, so you get one accountable point of contact, a fixed-price contract, and a 3-year workmanship warranty on the finished build.

§ 06Is UHS a licensed general contractor for ADU work in Texas?

Texas does not issue a state general contractor license, so no remodeler in DFW can truthfully call itself a “licensed general contractor.” What matters is the substance: UHS is fully insured, pulls all required permits, and uses licensed trades for the electrical, plumbing, and mechanical work your ADU needs to pass inspection. With 5,875+ projects completed since 2014 and 500+ five-star reviews, we manage the zoning, design, and inspection process so your backyard casita is built right the first time.