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ADU construction in San Antonio typically costs between $90,000 and $220,000 for a complete detached unit, with most homeowners landing between $130,000 and $180,000 for a one-bedroom or two-bedroom unit with a kitchen and bath. Smaller garage conversions run $30,000 to $80,000, while attached additions configured as ADUs fall in the $45,000 to $130,000 range.
At Elmstead Remodeling San Antonio, a Cedarwell company, you get a written price before any work starts. Not a range that drifts upward once the crew arrives. Graham Stein and our team put every material, labor hour, and permit cost on paper so you know what the ADU will cost before the first nail goes in.
Key Takeaways:
- Detached ADU: $90,000 – $220,000
- Garage conversion ADU: $30,000 – $80,000
- San Antonio permit fees and utility connections add roughly $8,000 – $20,000
- Written price before work starts, every time
- 365-Day Done Right Promise on every completed project
If you’re still exploring whether an ADU makes sense for your property, start with our ADU Construction in San Antonio guide for an overview of the process from survey to final inspection.
ADU Construction Cost Breakdown (2026)
Here’s what the numbers look like line by line for a typical detached ADU in San Antonio, based on 2026 market pricing. These are the ranges we see across Bexar County, from Alamo Heights to Stone Oak to the neighborhoods inside Loop 410.
| Cost Component | Typical Range (San Antonio) |
|---|---|
| Site preparation & foundation | $12,000 – $28,000 |
| Framing & structural | $18,000 – $40,000 |
| Roofing (shingle or metal) | $4,000 – $12,000 |
| Electrical rough-in & finish | $8,000 – $18,000 |
| Plumbing rough-in & finish | $9,000 – $20,000 |
| HVAC (mini-split or ducted) | $5,000 – $14,000 |
| Insulation & drywall | $6,000 – $14,000 |
| Kitchen (cabinets, counters, appliances) | $12,000 – $30,000 |
| Bathroom | $9,000 – $22,000 |
| Flooring throughout | $4,000 – $10,000 |
| Windows & doors | $3,000 – $8,000 |
| Permits, fees & utility connections | $8,000 – $20,000 |
| Painting, trim & finishes | $4,000 – $9,000 |
That adds up to roughly $102,000 on the low end and $245,000 on the high end, which is why we quote a practical range of $90,000 to $220,000 for most San Antonio ADU builds. The biggest variables are square footage, foundation type, and whether you’re connecting to city sewer or adding a separate septic system on a larger lot outside the city core.
In neighborhoods like Terrell Hills and Alamo Heights, we regularly see foundation work run higher because of expansive clay soil that needs pier-and-beam or post-tension slab engineering. In newer developments near Cibolo or along the far north side of San Antonio, slab-on-grade foundations on stable caliche typically cost less. That single soil difference can move your total by $10,000 or more.
What Affects ADU Construction Pricing in San Antonio
Every ADU project lands differently because every lot, every family, and every San Antonio neighborhood brings its own constraints. Here are the factors that move the number most.
- Foundation and soil conditions. San Antonio sits on a patchwork of expansive clay, limestone, and caliche. Clay-heavy lots, common inside Loop 410 and across older neighborhoods like Jefferson and Beacon Hill, require deeper footings or post-tension slabs. That alone can add $5,000 to $15,000 to the total. A lot with stable limestone or caliche usually stays at the lower end of the range.
- Detached vs. attached vs. garage conversion. A detached ADU starts from scratch and typically runs $90,000 to $220,000. An attached addition configured as an ADU with a separate entrance runs $45,000 to $130,000. Converting an existing garage runs $30,000 to $80,000 because the shell, roof, and slab already exist. The tradeoff: garage conversions often cost more per square foot to bring electrical, plumbing, and insulation up to code.
- Kitchen and bathroom scope. A full kitchen with named-brand cabinets from KraftMaid or Wellborn, Cambria or Silestone counters, and Kohler or Moen fixtures can run $12,000 to $30,000 inside the ADU. A kitchenette with a small sink, microwave, and compact refrigerator runs closer to $5,000 to $8,000. A full bathroom with a walk-in shower runs $9,000 to $22,000, and a tub-to-shower conversion in an ADU bathroom lands between $3,500 and $10,000. These choices are where two identical-looking ADUs end up $40,000 apart.
- Utility connections and permitting. San Antonio’s Development Services Department requires permits for any ADU over 200 square feet, and connecting to CPS Energy and SAWS water/sewer adds real cost. Tapping into an existing sewer line is cheaper than running a new lateral to the street. If the ADU sits far from existing utilities, trenching alone can add $4,000 to $10,000. Permit and impact fees in San Antonio typically run $8,000 to $20,000 depending on square footage and location.
- HVAC choice. A ductless mini-split system for a 400 to 600 square foot ADU runs $5,000 to $9,000 installed. Running ductwork from the main house is rarely cheaper once you account for the complexity and the load calculations. For larger ADUs over 800 square feet, a dedicated ducted system runs $8,000 to $14,000. San Antonio summers don’t forgive a poorly sized HVAC unit, so we calculate load based on the ADU’s orientation, window placement, and insulation levels, not a rule of thumb.
- Finish level and material choices. A rental-ready ADU with laminate counters and stock cabinets lands lower. A multigenerational suite built for parents or adult children, with James Hardie siding outside and Schluter waterproofing in the shower, lands higher. Both choices are legitimate. The written price you get from us just needs to reflect the choice you actually made.
ADU Construction Cost by Type in San Antonio
| ADU Type | Typical Size | San Antonio Price Range |
|---|---|---|
| Garage conversion ADU | 300 – 500 sq ft | $30,000 – $80,000 |
| Attached ADU (addition with separate entrance) | 400 – 800 sq ft | $45,000 – $130,000 |
| Detached one-bedroom ADU | 400 – 700 sq ft | $90,000 – $180,000 |
| Detached two-bedroom ADU | 700 – 1,000 sq ft | $150,000 – $220,000 |
These figures reflect what we see across San Antonio in 2026, from older lots in Government Hill and Dignowity Hill where setbacks and easements shape the design, to larger suburban lots near Helotes and Bulverde where a detached unit has room to breathe.
How to Save on ADU Construction
Saving money on an ADU in San Antonio doesn’t mean cutting corners. It means making choices that reduce labor hours and material waste without reducing the quality of what you live with.
Convert the garage if you have one and don’t need it for parking. The slab, walls, and roof are already there, which is why a garage conversion runs $30,000 to $80,000 versus $90,000 to $220,000 for a detached new build. Keep the kitchen compact. A kitchenette with a small sink and under-counter refrigerator costs a fraction of a full kitchen with custom cabinets. Choose a mini-split over ducted HVAC for ADUs under 600 square feet. And if the lot allows, position the ADU close to existing utility lines so trenching stays short.
Ask about phasing. If the budget is tight, you can build the shell with a rough-in for the kitchen and bath, then complete the finishes in a second phase. Not every family wants that, and the overall cost is usually slightly higher when phased, but it spreads the spend across time. We’ll put the phased numbers in writing too, so there’s no surprise later.
Every Elmstead Remodeling San Antonio project starts with a free estimate. Call (432) 233-0976 and we’ll walk through your lot, your goals, and a written price before any work starts. No estimate that grows after the crew arrives.
Why the Written Price Matters on an ADU
ADUs are large enough that even a 5% overage is real money, and a 15% overage changes whether the project makes financial sense at all. That’s why the Cedarwell Care Promise includes a written price before any work starts, on every project. Not after demolition. Not after the slab is poured. Before the first shoe cover goes on.
When our crew arrives, they are background-checked and uniformed, and they lay drop cloths on the floors and put shoe covers on at the door. If your kids are napping, we run quiet tools where possible. If you have pets, we choose pet-safe products where there is a choice, and we ask before we move anything. Before the crew leaves, we take a photo of the clean-up, and that photo is part of your project record. That’s the C.A.R.E. approach: Clean up like it’s our own home, Ask before we move or touch anything, Respect the family’s time and quiet hours, Explain the price before the work.
And the 365-Day Done Right Promise means if something isn’t done right after the project is complete, we make it right. That’s stamped on every ADU we build in San Antonio.
FAQs – ADU Construction Cost
How much does a one-bedroom ADU cost in San Antonio?
A detached one-bedroom ADU in San Antonio typically costs $90,000 to $180,000, with most projects landing between $120,000 and $160,000. The range covers a full kitchen, full bathroom, mini-split HVAC, and standard finishes. Call (432) 233-0976 for a written price on your specific lot, free of charge.
Is it cheaper to convert a garage or build a detached ADU?
Converting an existing garage is almost always cheaper, running $30,000 to $80,000 versus $90,000 to $220,000 for a detached new build. The garage already has a slab, walls, and a roof. The tradeoff is that garage conversions often cost more per square foot to bring electrical, plumbing, and insulation up to current code. If you’re weighing both, call (432) 233-0976 and we’ll price both options for your specific property.
What do San Antonio ADU permits cost?
Permit fees, impact fees, and utility connection charges for an ADU in San Antonio typically run $8,000 to $20,000. The exact figure depends on square footage, whether you connect to city sewer or need an alternative system, and the requirements of San Antonio’s Development Services Department. This cost is included in the written price we provide before any work starts.
How long does ADU construction take in San Antonio?
A detached ADU in San Antonio typically takes 5 to 9 months from permit approval to final inspection. Garage conversions run 3 to 6 months. San Antonio’s permit review timeline varies by workload at Development Services, so we submit as early as possible and sequence work to avoid delays. Your written estimate includes a project schedule, not just prices.
Can you build an ADU on my San Antonio lot?
Most single-family lots in San Antonio can accommodate an ADU, but setbacks, easements, lot size minimums, and historic district requirements vary by neighborhood. Lots inside Alamo Heights, Terrell Hills, and designated historic districts like King William often have additional review layers. We verify feasibility as part of the free estimate. Call (432) 233-0976 and we’ll check your address against current San Antonio code.
What does an ADU cost per square foot in San Antonio?
ADU construction in San Antonio typically runs $180 to $320 per square foot for a detached build, with smaller units trending toward the higher end because fixed costs like permits, utility connections, and site prep are spread across fewer square feet. Garage conversions run $100 to $200 per square foot. For an exact number on your project, call (432) 233-0976 for a free estimate.
Get a Written Price for Your San Antonio ADU
Whether you’re planning a rental unit, a multigenerational suite for aging parents, or a quiet workspace at the back of the lot, the first step is the same: a conversation about what you need, followed by a written price. No vague ranges. No growing estimates. Just a number you can plan around, from a team that treats your home like a home.
Call Elmstead Remodeling San Antonio at (432) 233-0976 for a free estimate. Graham Stein and our team answer the phone live, 24/7, and we’re glad to walk you through ADU construction costs in San Antonio, from the first survey to the final walkthrough.
Pricing reflects the San Antonio market as of 2026. Elmstead Remodeling San Antonio offers free estimates – call (432) 233-0976.
Written by Graham Stein, Owner at Elmstead Remodeling San Antonio, serving San Antonio since 2005.
What Our Customers Say
"Kitchen and living room refresh. Shoes off, floors covered, cleanup every evening. They checked with us before any change. Treated our home with real care."
- Dwight Harmon"Kitchen and living room refresh. What stood out was the respect for our home, shoes off, floors covered, cleanup every evening. They checked with us before any change. Beautiful result."
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