Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Fast, Reliable Home Additions & ADU Across Sinton
Home additions and ADU construction in Sinton typically run $45,000 to $130,000 for a room addition and $90,000 to $220,000 for a full detached ADU, with garage conversions landing between $30,000 and $80,000. Those are honest starting points, not bait numbers. But before you touch a single 2×4 in Sinton, you need a builder who understands the caliche hardpan under your lot, the TWIA windstorm requirements on every county permit, and the Vertisol clay that shifts foundations across 78387. That’s us. Call (877) 610-1318 and we’ll walk your property and give you real numbers.
Most Sinton homeowners we meet have been through this before with someone else. A handshake promise. A scope that grew. A permit that never got pulled. Barrett & Sons Construction exists because Tom Barrett got tired of watching neighbors get burned that exact way. We put every scope, every allowance, and every change order in writing before a single nail moves, and Tom’s name is on the truck. If you’re planning a room addition off your kitchen or a detached ADU behind your house on Sodville Street, we’d rather show you the paperwork than tell you a story.
Why Barrett & Sons Construction Is Sinton’s Preferred Home Additions & ADU Company
We’re not a franchise dispatching strangers from three states away. Barrett & Sons was founded in 1998, and Tom Barrett and his sons are on-site most days. That matters in a town like Sinton, where word travels fast and a contractor’s reputation lives or dies at the hardware store. Tom publishes his name, address, and license number. Look it up before you sign anything. Ask anyone on your street, or check with the county. You’ll find we’ve been doing this for over 29 years, and the 90-Day Done Right Promise is written on every contract. If it’s not done right, Tom comes back. One call.
We serve Sinton from our scheduling and dispatch hub in the Dallas-Fort Worth area, with crews working locally in San Patricio County. A live person answers the phone 24 hours a day, seven days a week. When you call about an ADU or a second-story addition on Main Street, you’re not leaving a voicemail for an out-of-state call center. You’re talking to someone who can pull up your file and tell you when the estimator will roll up. No trip charge inside the county, and a free second opinion on any written estimate you’ve already gotten.
Our Home Additions & ADU Services in Sinton
Our Home Additions & ADU team covers the full range, from a single bedroom bump-out to a permitted detached dwelling unit. Every eligible job in Sinton includes permits pulled and inspections signed. The permit inspector works for you, not for us, and that’s exactly how we like it.
ADU Design & Permitting
Building an ADU in Sinton means navigating TWIA windstorm certification, TDI inspections, and San Patricio County code. We handle the design drawings, the engineering for enhanced wind loads, and the permit package from start to finish. We also know the caliche question before the backhoe arrives, because we test-hole on every site where a new slab or utility trench is planned. An allowance that isn’t on paper is a surprise waiting for a date, and that applies double to site work in 78387.

Garage Conversion ADU
Many Sinton homes built in the 1950s and 1960s have attached or detached garages that are underused and already tied to the house footprint. Converting one to an ADU often runs $30,000 to $80,000, and it’s a smart way to add rental income or space for an aging parent. The catch here is foundations. Those older slabs and pier-and-beam setups frequently show differential settlement from the Vertisol clay. We inspect and shore up before we frame, and every fix gets its own written change order.

New Detached ADU
For a standalone unit in a Sinton backyard, expect $90,000 to $220,000 depending on square footage, finishes, and the condition of your lot. The Coastal Bend humidity means we spec corrosion-resistant fasteners and moisture-rated sheathing as standard. The wind zone means impact-rated windows and strapping details that a contractor from an inland county would never think about. We do. Hurricane Harvey’s track through this region is not a distant memory here, and our framing decisions reflect it.

Junior ADU & Interior Conversion
A junior ADU, or an interior conversion of an existing bedroom wing or oversized utility room into a private attached unit, is often the most affordable path. These projects in Sinton commonly run $45,000 to $130,000 depending on whether you’re adding a separate entrance, a kitchenette, or just reconfiguring interior walls. We also handle Kitchen Remodeling in Sinton when your addition opens into an existing kitchen wall, and Bathroom Remodeling in Sinton when the new unit needs its own bath. One crew, one schedule, one set of permits.

What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Sinton
We install materials you can look up, not mystery brands off a van. If your Sinton addition includes a paver patio, walkway, or driveway apron, we work with Techo-Bloc and Cambridge Pavers. For site prep, concrete, and footing work, we specify Quikrete and Oldcastle products rated for the Coastal Bend’s moisture and salt exposure. When we quote a paver patio for your new sunroom off North Sunset Drive, the brand is in the contract. You can check the spec before you sign, and you’ll see the exact product on the delivery ticket.
Common Home Additions & ADU Problems We See in Sinton Homes
We walked into the same four issues again and again across Sinton. Here’s what they are, and here’s why they matter to your addition or ADU budget.
- Caliche hardpan under the excavation. Beneath Sinton’s topsoil sits a dense caliche layer that stops backhoe buckets cold. Out-of-area contractors who bid without test holes routinely blow schedules and budgets on this one factor alone. We test-hole before we bid, so your concrete quote already accounts for jackhammer time.
- Expansive Vertisol clay and foundation movement. San Patricio County’s clay soils swell in wet months and shrink in drought. Older slabs and pier-and-beam foundations across Sinton show the effects. An addition tied to a moving foundation is a cracked addition, so we inspect, and if piers or leveling are needed, it’s in the first written change order you see.
- TWIA windstorm compliance gaps. Sinton sits inside the Texas Windstorm Insurance Association’s designated catastrophe zone. That means new construction and major renovations must meet enhanced wind-load standards and pass mandatory TDI windstorm inspections before TWIA coverage is issued. Contractors who skip this put your insurance and your resale at risk. We don’t skip it, and we show you the inspection paperwork.
- Deferred maintenance from ownership transitions. Many of Sinton’s mid-20th-century wood-frame and brick-veneer homes have passed through multiple owners without major upkeep. We regularly uncover rotted sill plates, undersized existing headers, and tired wiring where a new addition connects. We surface it before framing, not after the drywall hides it.
Pricing for Home Additions & ADU in Sinton, TX
Here are the numbers for Sinton’s market, straight and without sugarcoating.
- Room addition (single story): $45,000 to $130,000, depending on size, foundation condition, and whether it includes plumbing or a new roofline.
- New detached ADU (full unit with kitchen and bath): $90,000 to $220,000. The caliche depth and TWIA engineering on your lot are the big swing factors.
- Garage conversion ADU: $30,000 to $80,000. Older slab garages typically need leveling or moisture barrier work first.
- Junior ADU or interior conversion: $45,000 to $130,000. Interior reconfigurations avoid a lot of the site work, which keeps them on the lower end.
- ADU site prep and utility tie-ins: $7,000 to $18,000, depending on trenching through caliche and distance to sewer or septic.
Every estimate we give you is a written, line-item quote. Every change after that is a written change order. You never get a surprise invoice at the end, because the allowance that isn’t on paper is a surprise waiting for a date. Call (877) 610-1318 to schedule your free estimate. No trip charge inside the county.
We Also Serve Cities Near Sinton
Beyond Sinton, our Home Additions & ADU in Sinton crews regularly work in Portland, Robstown, Corpus Christi, and Ingleside. If you live in any of those communities, same rules apply: written scopes, written change orders, permits pulled, and Tom’s name on the truck. Call (877) 610-1318 and we’ll set a time to come out.
Serving Sinton, TX - Our Local Coverage Area
We’re based in the Sinton area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Home Additions & ADU in Sinton
A room addition in Sinton typically runs $45,000 to $130,000, while a full detached ADU lands between $90,000 and $220,000. The two factors that move your number most are the condition of your foundation and how much caliche the excavator hits. Call (877) 610-1318 for an exact quote - estimates are free, and no trip charge inside the county.
Yes. Every new addition and ADU we build in Sinton is engineered to meet the Texas Windstorm Insurance Association’s enhanced wind-load standards, and we pull the mandatory TDI windstorm inspections before the project closes. We show you the inspection paperwork. The permit inspector works for you, not for us.
Most Sinton room additions run 8 to 16 weeks from permit to final walk-through. A detached ADU typically runs 4 to 8 months depending on size, site conditions, and TWIA inspection schedules. Caliche and foundation surprises are the usual delay drivers, which is why we test-hole before we even finalize your quote. Call (877) 610-1318 and we’ll give you a written schedule with your estimate.
Only if the scope changes, and only on paper. Every price change at Barrett & Sons Construction is a written change order that you review and approve before work proceeds. No exceptions, no verbal handshakes, no “we’ll settle up at the end.” That’s the 90-Day Done Right Promise culture, not a marketing line.
We pull permits and schedule inspections on every eligible job in Sinton. Every scope that needs a permit gets one, every change that affects code gets re-reviewed. We’ve met too many Sinton homeowners who were told permits were optional by the last contractor. They’re not, and we treat them accordingly.
Written by Tom Barrett, Owner at Barrett & Sons Construction. Call (877) 610-1318 for your free Sinton home addition or ADU estimate.







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