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Get your free estimateHow Much Does an ADU Cost in San Antonio?
An ADU in San Antonio typically costs between $145,000 and $280,000 for a turnkey one-bedroom unit in 2026. A garage conversion runs lower, around $95,000 to $160,000, while a detached two-bedroom ADU with premium finishes lands between $240,000 and $360,000. These are real numbers from the San Antonio market, where labor rates run 15 – 20% below Austin and permitting moves faster than either coast.
That said, the price you’ll actually pay depends on whether you go prefab or site-built, what’s already on your lot, and how far your property sits from utility hookups. We walk every homeowner through a written price before any work starts, so the number you see is the number you sign.
Key Takeaways
- San Antonio ADU pricing in 2026 runs $145,000 – $360,000 for most projects, with garage conversions starting near $95,000.
- Prefab ADUs from brands like Abodu, Dvele, and Boxabl often cut 2 – 4 months off construction time compared to site-built.
- Permitting fees in San Antonio add $3,500 – $9,000 depending on project size and plan review complexity.
- Financing options now include FHA’s 203(k) and renovation refi products that can roll ADU costs into your mortgage.
- Benson ADU San Antonio provides a written price before starting and a 365-Day Done Right Promise on every project.
ADU Cost Breakdown in San Antonio (2026)
Here’s what you’re actually paying for when you build an ADU in San Antonio. We break this down by line item because most contractors hand you one lump sum and expect you not to ask questions. We’d rather you see the whole picture.
| Cost Component | Garage Conversion | Detached ADU (1 Bed) | Detached ADU (2 Bed) |
|---|---|---|---|
| Design & Engineering | $4,000 – $7,500 | $8,000 – $14,000 | $10,000 – $18,000 |
| Permits & Plan Review | $3,500 – $6,500 | $4,500 – $8,500 | $5,500 – $9,000 |
| Site Prep & Foundation | $2,000 – $5,000 | $14,000 – $28,000 | $18,000 – $32,000 |
| Framing & Structure | $8,000 – $18,000 | $30,000 – $55,000 | $40,000 – $70,000 |
| Plumbing | $9,000 – $18,000 | $14,000 – $26,000 | $18,000 – $32,000 |
| Electrical | $7,000 – $14,000 | $10,000 – $18,000 | $12,000 – $22,000 |
| HVAC | $5,000 – $9,000 | $7,000 – $13,000 | $9,000 – $15,000 |
| Insulation & Drywall | $6,000 – $11,000 | $9,000 – $16,000 | $11,000 – $19,000 |
| Flooring, Tile, Fixtures | $8,000 – $16,000 | $12,000 – $24,000 | $15,000 – $30,000 |
| Kitchen & Bath | $10,000 – $22,000 | $16,000 – $32,000 | $20,000 – $40,000 |
| Paint, Trim, Final Details | $3,000 – $6,000 | $5,000 – $9,000 | $6,000 – $11,000 |
| Project Management & GC Fees | $8,000 – $16,000 | $14,000 – $32,000 | $19,000 – $42,000 |
| Contingency (5 – 8%) | $4,800 – $9,000 | $7,500 – $15,000 | $9,500 – $20,000 |
| Total Range | $95,000 – $160,000 | $145,000 – $280,000 | $240,000 – $360,000 |
That covers the cost of construction hardware, labor, and materials. It does not include things like upgrading your electrical panel if the existing one can’t handle a new unit (that’s another $2,500 to $6,000), or the cost of running a longer sewer line if your ADU sits far from the main house drain.
Prefab vs. Site-Built Costs
Prefab ADUs from names like Abodu, Dvele, Mighty Buildings, and Boxabl usually land within 10% of site-built pricing, but they compress the timeline. A site-built ADU in San Antonio takes 9 to 14 months from design to keys. A prefab unit from Abodu or Boxabl is often installed in 3 to 5 months after permits clear.
That speed has real financial value, especially if you’re building to generate rental income. A one-bedroom ADU in neighborhoods like Alta Vista or Beacon Hill rents for $1,100 to $1,500 a month. Six fewer months of construction means six extra months of rent, which translates to about $6,600 to $9,000 in your pocket before the site-built version would even be finished.
We’re an authorized builder for every major prefab brand, including Cover, Plant Prefab, and Tuff Shed. That means we can show you side-by-side pricing, not just push one product at you.
What Affects ADU Pricing in San Antonio
No two ADUs cost the same, and the factors below explain most of the price spread we see across San Antonio. Some of these are fixed by your lot, others are choices you control.
- Lot slope and soil condition. If your lot sits on clay-heavy soil common in areas around Loop 1604, your foundation will need deeper piers or a grade beam. That adds $6,000 to $14,000 compared to a flat lot with stable soil. If your property is in the Hill Country’s limestone belt, expect rock excavation costs during utility trenching.
- Distance to existing utilities. The closer your ADU sits to the main water, sewer, and electrical connections, the cheaper the project. Running a sewer line an extra 40 feet can add $4,000 to $9,000 depending on depth and soil type.
- Kitchen and bathroom count. A single bathroom with a kitchenette costs far less than a full kitchen plus two bathrooms. Each additional bathroom typically adds $18,000 to $30,000 to the budget.
- Prefab versus site-built. Prefab units have predictable material costs but sometimes higher shipping and crane fees. Site-built ADUs have more flexibility on layout but more weather-related delays and higher labor hours.
- Finishes and fixtures. Builder-grade flooring, stock cabinets, and standard tile run $12,000 to $18,000 for a one-bedroom unit. Mid-grade upgrades push that to $20,000 to $35,000. If you want custom millwork or James Hardie cladding instead of basic fiber cement board, expect another $5,000 to $10,000 above base pricing.
- Permitting complexity. Most San Antonio ADUs sail through the Development Services Department, but anything requiring a variance (like a detached unit taller than 20 feet in some zoning districts) can add months and $2,000 to $5,000 in additional fees and engineering reviews.
How to Save on an ADU in San Antonio
Saving money doesn’t mean cutting corners that you’ll regret in year three. It means making smart decisions early, before the first shovel turns.
- Pick a prefab shell and customize lightly. Brands like Abodu and Boxabl have already engineered their floor plans to be efficient. Heavy customization is where prefab pricing climbs. Keep the standard layout and spend your money on fixtures instead of structural changes.
- Convert existing space before building new. If you have an underused garage or a covered patio that never gets used, converting it into an ADU typically costs 35 – 50% less than building a detached unit from scratch. You already have the slab, the roof, and at least one wall.
- Keep the footprint compact. A well-designed 500-square-foot ADU with a thoughtful layout can feel larger than a poorly planned 700-square-foot unit. Every 100 square feet you add runs $18,000 to $30,000 in San Antonio.
- Compare financing early. Cash buyers skip interest, but that’s not realistic for most people. FHA’s 203(k) rehabilitation loan lets you roll ADU construction into your mortgage refi, and several San Antonio credit unions now offer ADU-specific construction loans with lower rates than personal loans.
- Ask for a written price itemization. When a contractor hands you one number with no breakdown, you can’t tell which line items are inflated. At Benson ADU San Antonio, every estimate includes a full written price breakdown before work starts. Call (430) 258-2928 and we’ll walk you through it line by line.
Frequently Asked Questions About ADU Costs in San Antonio
How much does a garage conversion ADU cost in San Antonio?
A garage conversion ADU in San Antonio costs $95,000 to $160,000 in 2026, depending on the condition of your existing structure, plumbing, and electrical work. If your garage slab has settled or the roof needs rebuilding, you’ll land on the higher end of that range. Conversions nearly always beat detached new builds on price because the shell already exists. Call (430) 258-2928 for a written estimate on your specific garage.
Is it cheaper to build an ADU or a home addition in San Antonio?
An attached home addition in San Antonio runs $130,000 to $240,000 for a comparable finished space, which is slightly cheaper than a detached ADU in most cases. You save on foundation work and utility runs because the addition shares walls with the main house. But an ADU generates rental income that an addition typically can’t, since it has its own entrance and kitchen. We build both, and we’ll show you the real numbers for your lot before you commit.
How long does an ADU take to build in San Antonio?
A prefab ADU from Abodu, Boxabl, or Dvele typically goes from permit to move-in in 3 to 6 months, while a site-built ADU takes 9 to 14 months. San Antonio’s permitting process moves faster than Austin or Houston, but plan review still takes 4 to 8 weeks in most cases. The single biggest variable is how quickly your plans get finalized, which is why we put everything in writing from day one.
Do ADUs add value to a home in San Antonio?
In most San Antonio neighborhoods, a well-built ADU adds 60 – 80% of its construction cost to the home’s appraisal value, and a rental unit adds a predictable income stream that buyers like. Appraisers in Bexar County have gotten better at valuing accessory units since 2022, especially where comps exist. The ADU pays you twice: once in rental income and once at resale.
Can I finance an ADU in San Antonio?
Yes. Common options include a home equity line of credit (often the lowest rate), a cash-out refinance, FHA 203(k) renovation loans, and construction-to-permanent loans from several San Antonio credit unions. If you have equity, you’ll likely get better terms than with an unsecured personal loan. We’ll help you coordinate with your lender so the draw schedule matches our construction timeline.
More questions? Call us at (430) 258-2928 and a live person will answer, any time of day.
What to Expect When You Call Benson ADU San Antonio
You’ll reach a person, not a voicemail. We ask about your property, your goals for the ADU, and your rough budget. Then we schedule a site visit.
At the site visit, our background-checked, uniformed team walks your lot, checks utility access, and talks through what’s possible on your specific property. Within a few days, you’ll receive a written price that covers the full project scope. No verbal ballparks that shift later, no surprises at the door.
Every Benson ADU San Antonio project includes The Relay Visibility Guarantee. That means a written price before work starts, real-time project tracking, before-and-after photos, and a digital invoice you can pay by link. If anything isn’t done right within 365 days of completion, we make it right. That promise is stamped on every project we build.
Troy Eastman leads the team at Benson ADU San Antonio, and he’s the person you’ll talk to when you call. The company is part of the Relay Home Co. family, founded in 2006, with locations across Texas and beyond. Each location is independently owned and operated under the same guarantee.
Ready to Get a Real Number for Your ADU?
Stop guessing and get a written price. Call Benson ADU San Antonio at (430) 258-2928 for a free ADU estimate, or visit our home page to see how we approach every project. We’ll give you real numbers for your lot, your timeline, and your budget, and we’ll stand behind them in writing.
Written by Troy Eastman, Owner at Benson ADU San Antonio, serving San Antonio homeowners with written pricing and a 365-Day Done Right Promise.
Pricing reflects the San Antonio market as of 2026. Benson ADU San Antonio offers free estimates – call (430) 258-2928.
What Our Customers Say
"Solid job. Cabinets arrived late but they adjusted the schedule."
- Eli K."Plumbing and electrical passed on the first inspection."
- Alan B."Room addition off the kitchen. Framing, drywall, and paint all done well."
- Wade L.
