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AfterHow Much Does ADU Construction Cost in San Antonio?
ADU construction in San Antonio typically costs between $90,000 and $220,000 for a complete detached unit in 2026. Most homeowners building a standard one-bedroom ADU of roughly 600 to 800 square feet land between $150 and $275 per square foot, though attached conversions and garage remodels run lower. The final number depends on whether you’re building from the ground up, converting a garage, and which finish level you choose.
If you’re planning an ADU in neighborhoods like Alamo Heights, Terrell Hills, Monte Vista, or the growing corridors around Stone Oak and Helotes, you’re making a smart call: San Antonio’s ADU construction scene has exploded over the last three years as the city streamlined its permit process. Before you commit, we’ll walk you through exactly where the money goes, what drives the price up or down, and how to get a written number you can actually plan around.
ADU Construction Cost Breakdown (2026)
Here’s where every dollar goes on a typical detached ADU in the San Antonio market. These are real ranges we see on bids across Bexar County, not national averages pulled from a cost calculator.
| Cost Component | Typical Range | Notes |
|---|---|---|
| Site prep & foundation | $8,000 – $22,000 | Includes demo (if needed), grading, slab or pier-and-beam foundation. Clay-heavy San Antonio soil means some lots need extra compaction work. |
| Framing & structural | $18,000 – $40,000 | Lumber, engineered beams, roof structure. Texas wind code adds a bit of cost versus other markets. |
| Electrical | $7,000 – $15,000 | New panel feed or subpanel, wiring, fixtures, lighting, outlets. |
| Plumbing | $6,000 – $14,000 | Water supply, drain lines, water heater or tankless unit, bathroom and kitchen rough-ins. |
| HVAC | $5,000 – $12,000 | Mini-split systems are the most common choice for ADUs; a ducted central unit costs more. |
| Drywall, insulation & paint | $6,000 – $12,000 | R-13 to R-19 insulation to meet San Antonio’s IECC climate zone requirements, plus finishing. |
| Flooring | $3,500 – $8,000 | LVP, tile, or engineered hardwood. Tile stays cooler in South Texas summers. |
| Bathroom (full) | $9,000 – $28,000 | Same range as a full bathroom remodel. Includes tub or shower, vanity, toilet, tile, fixtures. |
| Kitchen or kitchenette | $6,000 – $25,000 | A kitchenette with a sink, microwave, and compact fridge runs low; a full kitchen with cabinets and appliances runs high. Cabinet installation alone is $4,000 – $13,000. |
| Windows & doors | $2,500 – $7,000 | Low-e windows are a must in San Antonio heat. Exterior door, plus interior doors. |
| Roofing | $5,000 – $14,000 | Asphalt shingles or metal, tied into the main structure or on a pitched roofline. Roof replacement on a standalone ADU mirrors main-home pricing per square foot. |
| Exterior finish & siding | $4,000 – $12,000 | Fiber cement (James Hardie), stucco, or brick veneer to match the primary house. |
| Permits, plans & engineering | $4,000 – $10,000 | Building permit, site plan, architectural drawings, structural engineering. San Antonio’s Development Services department has a dedicated ADU review path, but fees still add up. |
| Site work & utilities | $3,000 – $12,000 | Utility connections, drainage, landscaping repair, concrete walkways or a small patio pad. |
| Contingency (smart money) | $5,000 – $15,000 | Every good GC builds in 5-10% for the unknown. San Antonio’s older lots in Castle Hills or Jefferson hide surprises: old sewer lines, buried debris, roots through clay. |
What Drives Cost Up or Down
Three things move the needle more than anything else. First, attachment type: a garage conversion in San Antonio runs $30,000 to $80,000 because the shell already exists, while a fully detached new-build starts at $90,000 and climbs from there. Second, finish level: builder-grade fixtures and LVP flooring keep you near the bottom of the range, while Kohler fixtures, Cambria countertops, and custom cabinetry push you past $200 per square foot. Third, site conditions: lots with expansive clay soil, steep grades, or long utility runs add real cost that no online calculator captures.
What Affects ADU Construction Pricing in San Antonio
- Soil and foundation work. San Antonio sits on expansive clay. In neighborhoods like Leon Valley and parts of the Northside, soil movement is a known issue, and piers or additional slab reinforcement can add $3,000 to $8,000 before framing even starts.
- Permit path and zoning. The City of San Antonio updated its ADU ordinance to allow units on most single-family lots, but setbacks, lot coverage rules, and historic district overlays (think King William or Monte Vista) add review time and sometimes design constraints. Expect plan review fees, impact fees, and water/sewer connection charges.
- Utility distance. If your ADU sits at the back corner of a 100-foot lot, you’re trenching electrical and water lines the entire way. Each additional foot of trenched utility run is a real cost, not a rounding error.
- Finish selections. A $90,000 ADU and a $220,000 ADU are structurally similar. The gap is in tile versus LVP, stock cabinets versus KraftMaid custom, standard windows versus low-e impact-rated units, and a basic mini-split versus a zoned ducted system.
- Access for equipment. Gated lots, narrow drives, or ADUs tucked behind the main home with poor access slow down excavation and material delivery. If a skid steer can’t get back there, labor costs go up.
- Labor availability and season. San Antonio’s construction season runs year-round, but summer heat pushes framing crews to start earlier and work slower. Peak season bids (spring through early fall) can come in 5-10% higher than winter quotes.
How to Save on ADU Construction
You can save real money without cutting corners, but it takes decisions made before the first day of demo.
- Convert instead of build new. A garage conversion in San Antonio starts around $30,000 and often ends below $80,000. You skip foundation work, framing, and roofing entirely. If your detached garage has solid bones, this is the single biggest money move.
- Keep the roofline simple. A single slope or standard gable roof costs thousands less than a complex hip roof with dormers. Every corner and valley adds framing labor, roofing labor, and future leak potential.
- Choose a kitchenette over a full kitchen. Dropping from a full kitchen (range, hood, full cabinetry, dishwasher) to a compact kitchenette with a refrigerator, microwave, and small sink can cut $8,000 to $15,000. For a rental ADU targeting a tenant who eats out or uses a hot plate, that trade-off is worth it.
- Buy finishes at one source. If you’re working with a contractor who has direct partnerships with brands like Cambria, Moen, and KraftMaid, you often get better pricing than retail. Make your selections early so ordering lead times don’t stall the job.
- Get a written price before work starts. This is the most underrated money-saver in the industry. A contractor who puts the full scope and dollar amount in writing before swinging a hammer is protecting you from change orders, surprise line items, and a final invoice that looks nothing like the estimate. At Sawyer Remodel San Antonio, that written price is standard on every ADU we bid, not an add-on you have to request.
- Ask about the guarantee. A 365-day promise on the work means if something fails after move-in, the fix is covered. Cheap bids that don’t back the work in writing cost more by year two. Free estimates are the starting point: call (432) 547-6806 and we’ll give you a real number for your specific lot, not a national average in an email.
FAQs – ADU Construction Cost
How much does it cost to build a 600 sq ft ADU in San Antonio?
A 600-square-foot detached ADU in San Antonio typically costs $90,000 to $165,000, depending on finishes and site conditions. That puts you at roughly $150 to $275 per square foot. If you convert an existing garage into that same 600-square-foot living space, the range drops to $30,000 to $80,000. For an exact number on your lot, call (432) 547-6806 and we’ll walk the site and give you a written estimate for free.
Is it cheaper to build an ADU or convert a garage in San Antonio?
A garage conversion is almost always cheaper, running $30,000 to $80,000 versus $90,000 to $220,000 for a new detached build. The savings come from skipping the foundation, framing, roof, and exterior finish work that a ground-up ADU requires. The trade-off is layout: you’re working within walls that already exist. The Relay Visibility Guarantee on any project means the price is written before work starts, so call (432) 547-6806 and we’ll compare both options for your property.
What does the city of San Antonio require for an ADU permit?
San Antonio requires a building permit, a site plan showing setbacks and lot coverage, and architectural/structural drawings for any ADU. Plan review and permit fees typically land in the $4,000 to $10,000 range when you include engineering. Historic districts like Monte Vista and King William add design review, and if you’re in a floodplain, there’s another layer. A contractor who handles permits for you saves weeks of back-and-forth with Development Services.
How long does ADU construction take in San Antonio?
A detached ADU takes 6 to 10 months from permit application to final inspection, depending on scope and weather. Garage conversions run faster, typically 3 to 5 months. The biggest variable is permit review time, which fluctuates with the city’s workload. Plan around your financing timeline and put a contingency in the schedule, not just the budget. We give live arrival time updates and photo updates throughout the build, so you’re never wondering where the project stands.
Do ADUs increase property value in San Antonio?
ADUs in San Antonio generally return 70% to 90% of construction cost in added property value, and the stronger return is in rental income: a quality one-bedroom ADU in a neighborhood like Mahncke Park or Tobin Hill rents for $1,100 to $1,800 per month. The caveat is that appraisals for ADUs remain inconsistent in Bexar County, so build because you need the space or the income, not purely as a flippable investment. If you need guidance on whether your lot makes sense, call (432) 547-6806 and we’ll give you a straight answer, not a sales pitch.
Why the Price They Quote You Should Be the Price You Pay
Every ADU contractor in San Antonio will give you a number. The question is whether that number still holds when the framing is up and the tile is going in. Most of the horror stories you hear about ADU projects running 30% or 40% over budget come from one thing: an estimate that was never a written price. The bid looked competitive, the handshake felt solid, and then the change orders started.
We built Sawyer Remodel San Antonio to run differently. The price gets written down before work starts. The number on the final invoice is the number you approved, because we do the legwork on soil conditions, permit fees, and utility runs before we commit to a dollar amount. That’s The Relay Standard, and it applies to every ADU we build, whether it’s a 400-square-foot studio behind a house in Beacon Hill or an 800-square-foot two-bedroom in Alamo Ranch. It includes a live arrival time so you know when our crew shows up, photo updates before and after key stages, and a digital invoice you pay from a link, not an envelope of paper.
And if something isn’t right after you’ve moved a tenant in or started using the space, the 365-Day Done Right Promise covers it. If it’s not done right, we make it right. That’s written into every project, not something you have to negotiate for. No hidden terms, no fine print, no “that’s not covered” phone call.
Material choices run through our direct partnerships with brands homeowners actually want: Cambria and Caesarstone countertops, Kohler and Moen fixtures, KraftMaid cabinetry, James Hardie siding, GAF roofing. You’re not picking from a mystery catalog of off-brand fixtures that look fine for a year and fail by year three. You’re choosing from proven manufacturers with warranties that back the install.
Luca Romano leads our ADU and home addition work in San Antonio. He’s walked more Bexar County lots than he can count, and he’ll tell you straight up whether your garage conversion makes sense, whether your setbacks will allow the footprint you want, and what your actual cost per square foot will be, not a national average from a chart. You won’t get a callback queue. You’ll get a straight answer.
If you’re serious about building an ADU in San Antonio, start with a free estimate. Call (432) 547-6806 and we’ll schedule a site visit, give you a written price, and map out the timeline. No pressure, no vague numbers, no disappearing act. Just a clear plan and a number you can take to the bank.
Written by Luca Romano, Owner at Sawyer Remodel San Antonio, serving San Antonio since 2005.
Pricing reflects the San Antonio market as of 2026. Sawyer Remodel San Antonio offers free estimates – call (432) 547-6806.
What Our Customers Say
"Quote was itemized and every change was approved in the app."
- Sasha L."Bathroom remodel. Tile and shower niche are flawless. Updates by text kept me in the loop."
- Hugh P."Floors and paint finished on time. Floors were sanded, stained, and the walls painted without any gaps in the schedule."
- Ron T.
