Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across New Braunfels
Home additions and ADU construction in New Braunfels typically run $45,000-$130,000 for a room addition and $90,000-$220,000 for a detached ADU, depending on site conditions, permitting, and finishes. The biggest cost variable most homeowners never see coming? Caliche. If your lot sits in the 78132 corridor toward Canyon Lake, excavation can hit limestone hardpan at 18 inches, and that changes everything about the foundation line. We’re Barrett & Sons Construction, and we’ve been pulling permits and building additions in this exact terrain long enough to price the rock work before the first machine shows up. Call (877) 610-1318 for a free estimate, and we’ll walk your lot with you before we quote a single number.
Key Takeaways: Home Additions & ADU in New Braunfels
- A room addition in New Braunfels runs $45,000-$130,000; a new detached ADU runs $90,000-$220,000; a garage conversion runs $30,000-$80,000.
- You’re dealing with Comal County permitting on acreage, not just city permits, and the difference changes timelines and setbacks.
- Caliche and limestone excavation in the 78132 and 78131 corridors adds real cost that out-of-market bids rarely include.
- Septic system setbacks and well-head easements can move your ADU footprint by 20 feet or more, and we scope that before quoting.
Why Barrett & Sons Construction Is New Braunfels’s Preferred Home Additions & ADU Company
Tom Barrett put his name on the truck in 1998, and his sons run the crews. That matters when you’re spending six figures on an addition or ADU in New Braunfels, because the person who shows up to walk your lot is the same person who signs the contract and the same person you’ll see at H-E-B on Saturday. We’re not a franchise dispatching strangers from out of state. We answer our own phone, we live in the area, and our local reputation in New Braunfels is built on one thing: written change orders before any scope moves, permits pulled on every eligible job, and a 90-Day Done Right Promise written into every contract.
New Braunfels homeowners have told us the same story for years. A national company quotes one price over the phone, then hands them a different bill when the excavator hits rock. We don’t work that way. When we scope an ADU off River Tree Drive or a second-story addition near Gruene, the allowance is on paper, the excavation risk is priced in, and the permit inspector’s sign-off is part of the job. That’s why homeowners in 78130, 78131, 78132, and 78135 keep calling us back. And why they refer us to their neighbors.
Our Home Additions & ADU Services in New Braunfels
ADU Design & Permitting
Building a detached ADU in New Braunfels means navigating both city and Comal County requirements, depending on your parcel. On acreage in the 78132 corridor, county septic setbacks and well-head easements can change where your structure sits by 20 feet or more. We handle that design work up front, pull every permit, and get the inspections signed. If you already have plans from another designer, we’ll review them against local setback rules before you spend another dollar.
Garage Conversion ADU
Converting an attached garage into an ADU in New Braunfels runs $30,000-$80,000 and is often the fastest way to add a rentable unit or in-law quarters without new foundation work. But if your home in 78130 sits inside a FEMA flood zone, the conversion may require flood-compliant framing and elevated mechanicals, and that has to be engineered correctly the first time. We’ve done enough of these to know what the floodplain administrator will ask for before we submit.
New Detached ADU
A new detached ADU on a New Braunfels Hill Country lot is a different animal from a suburban backyard cottage. You’re dealing with caliche excavation, septic separation distances, well-head easements, drainage requirements, and sometimes fire code setbacks on larger parcels. We price all of that before you sign. Our Home Additions & ADU team has built detached units from 600 to 1,200 square feet across Comal County, and we know which sites will need a hydraulic breaker before the machine shows up. Typical cost: $90,000-$220,000.
Junior ADU & Interior Conversion
A junior ADU converts existing interior space, like a finished basement, bonus room, or oversized utility room, into a self-contained unit with its own entrance, kitchenette, and bath. These projects run on the lower end of the addition price range and often don’t require new foundations, which means fewer surprises in New Braunfels’s rocky soils. The catch is that Comal County still applies occupancy and utility separation rules, and we handle the paperwork so your JADU is legal, not just livable.
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 New Braunfels
We install materials you can look up, not mystery brands off a van. On our addition and ADU jobs in New Braunfels, we regularly spec Schluter waterproofing systems in wet areas, Sterling fixtures where durability matters, and GAF roofing on any new or extended rooflines. When you call us about an addition that ties into an existing roof, we can match the current shingle profile or upgrade to GAF with a written line item, not a vague “roof work” allowance. Our suppliers stock these brands locally in the San Antonio metro, which means faster turnaround for New Braunfels jobs and fewer weeks waiting on a truck from out of state.
Common Home Additions & ADU Problems We See in New Braunfels Homes
- Caliche and limestone excavation not priced into the bid. In the 78132 and 78131 corridors, excavation crews regularly abandon standard digging and bring in a hydraulic breaker when they hit hardpan at 18 to 24 inches. If your contractor didn’t price rock work, that change order lands after the hole is open, and you’re stuck.
- Septic and well setbacks discovered after rough-in. On acreage served by well and septic, the county’s required separation distances can push an ADU’s foundation 20 feet or more from the original stake. When it’s found after plumbing is stubbed, somebody tears something out. We locate the well head and septic field before we draw foundation lines.
- Second-story additions on expansive clay-over-limestone soil without deep pier engineering. New Braunfels sits on soils that swell and shrink through Central Texas wet-dry cycles. A second-story addition that isn’t engineered for that movement will crack load-bearing walls within a couple of seasons.
- Flood zone framing overlooked in 78130. Parts of New Braunfels along the Guadalupe and Comal rivers fall inside FEMA flood zones. Additions in those zones need elevated slab designs and flood-compliant framing details that add cost and permitting time. We scope those requirements before the first inspection, not after a correction notice.
Pricing for Home Additions & ADU in New Braunfels, TX
Here are the numbers we’re quoting on New Braunfels jobs this season:
| Project Type | New Braunfels Price Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
What moves the number on your specific lot? Excavation is the biggest one. If we hit caliche at 18 inches, the foundation line goes up, and that’s a written change order before we keep digging. Septic and well setbacks also move the number, because they move the structure. Finishes matter too, but the site work is where New Braunfels projects diverge from flat-terrain pricing. We give free estimates, and every estimate includes the excavation risk priced for your specific parcel, not a generic “site prep” allowance. Call (877) 610-1318 to schedule a lot walk. We’ll bring the soil map.
We Also Serve Cities Near New Braunfels
Our crews work throughout the New Braunfels area every week, and we regularly run jobs in Cibolo, Schertz, Selma, and Universal City. If you’re in one of those towns and you’re planning a home addition or ADU, the same written change orders, permit discipline, and 90-Day Done Right Promise apply. For a closer look at our work in this area, see Home Additions & ADU in New Braunfels. Then call us and we’ll come walk your lot.
Serving New Braunfels, TX - Our Local Coverage Area
We’re based in the New Braunfels 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 New Braunfels
On acreage in the 78132 corridor outside city limits, you need a Comal County permit for a detached ADU, and you may need additional approvals for septic system modifications, well-head setbacks, and possibly floodplain review if any part of your parcel touches a flood zone. Inside New Braunfels city limits, you’ll go through the city’s building department instead. We handle either path, and we’ll tell you which one applies to your parcel before we quote. Call (877) 610-1318 and we’ll look up your lot.
Rock excavation for an ADU foundation in New Braunfels typically adds $8,000-$25,000 depending on the size of the footprint and how deep the caliche runs. In the 78132 corridor toward Canyon Lake, it’s common to hit hardpan between 18 and 30 inches, which means a hydraulic breaker and sometimes a rock hammer. We price this from soil maps and neighboring site data before you sign, so it’s a line item, not a surprise. Call (877) 610-1318 for a specific number on your lot.
A 900-sq-ft detached ADU on a Hill Country lot in New Braunfels typically takes 6 to 10 months from permit submission to final inspection. The variables are excavation, septic system approval, and Comal County review times, which run longer than city reviews. If we hit significant rock, add time for the breaker. We’ll give you a written schedule with milestones before we start, and we’ll update it in writing if anything changes. Call (877) 610-1318 for a timeline specific to your site.
Yes, you can convert an attached garage into an ADU in a FEMA flood zone in 78130, but the conversion must meet floodplain requirements for the lowest floor elevation, and you may need to elevate mechanical systems and use flood-resistant materials below the base flood elevation. Some 78130 properties also carry restrictions based on their specific flood zone designation. We’ll pull your flood map and tell you what’s required before you spend money on plans. Call (877) 610-1318 and we’ll pull the map for free.
Whether an ADU on a well and septic lot in New Braunfels needs a separate septic system depends on the existing system’s capacity and the county’s current setback rules. Many older systems in Comal County were sized for a smaller household, and adding an ADU with a second bathroom or kitchen can exceed the permitted flow. In those cases, you’ll need a new system or a system expansion. We bring in a licensed septic designer at the beginning of the design phase so you know the answer before you commit to a foundation. Call (877) 610-1318 and we’ll start the scoping.
Call Barrett & Sons Construction for Home Additions & ADU in New Braunfels
If you’re planning a room addition, detached ADU, or garage conversion in New Braunfels, start with a lot walk. We’ll walk the grade, check the soil, locate the septic and well, and give you a written estimate that prices the rock work, the setbacks, and the permits from day one. Everything goes on paper: scope, allowances, change orders. And every job carries our 90-Day Done Right Promise in writing. Call (877) 610-1318 to schedule your free estimate. Tom and his sons answer the phone.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving New Braunfels since 1998.