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 Boerne
A full home addition in Boerne typically runs $45,000-$130,000, while a separate ADU structure usually lands between $90,000 and $220,000. The exact number depends on whether you’re going up, going out, or converting what’s already there. If you’re in the 78006 or 78015 ZIP and wondering whether your lot can even support what you’re picturing, that’s a question worth answering before you fall in love with any floor plan. Call (877) 610-1318 and we’ll walk the property with you, no charge for the visit.
What most people don’t realize about Boerne is that the ground itself shapes nearly every addition and ADU decision. The limestone karst sitting just below the topsoil means excavation rarely goes the way a builder assumes it will. A crew that shows up without a rock saw burns a day before the first footing gets poured. We’ve been dealing with that limestone for 29 years, so our estimates account for it up front instead of surprising you mid-dig.
Why Barrett & Sons Construction Is Boerne’s Preferred Home Additions & ADU Company
Tom Barrett started this company in 1998, and his sons run the crews. When you call about an addition in Boerne, you’re not getting a call center an hour away. You’re getting a family that’s worked in Kendall County long enough to know which subdivisions in 78015 sit on shallow rock and which lots in 78006 drain toward Cibolo Creek. That’s not trivia. That’s the difference between a project that stays on budget and one that gets eaten alive by change orders.
Every estimate we give you comes in writing with the scope spelled out line by line. If a change comes up during the job, you get a written change order before any work happens. The allowance that isn’t on paper is a surprise waiting for a date. Our customers in Boerne don’t get builder-speak and vague promises. They get the same thing as our customers in Fair Oaks Ranch and Helotes: a name you can look up, a crew you’ll see at the hardware store, and a 90-Day Done Right Promise written on every contract.
Someone answers the phone when you call, day or night. Tom publishes his name, address, and license number so you can verify him before you sign anything. We pull permits on every eligible job and the inspector signs off before we consider it done. The permit inspector works for you, not for me. That’s why I like him.
Our Home Additions & ADU Services in Boerne
ADU Design & Permitting
Building an ADU in Boerne means answering two questions before you ever swing a hammer: what does the city allow, and what will the ground let you do? We handle both. The 78015 ZIP sits partly within the Edwards Aquifer Contributing Zone, which triggers impervious cover limits and TCEQ requirements that a Bexar County contractor working off standard permits routinely misses at the bid stage. Our Home Additions & ADU team handles design, site assessment, and the full permit process so you’re not stuck explaining aquifer rules to a plan reviewer on your own.
Garage Conversion ADU
Converting a garage into living space is usually the most budget-friendly ADU route in Boerne, with most projects running $30,000-$80,000. The catch is that older garage slabs in 78006 homes weren’t always poured with living-space loads or insulation in mind. We evaluate the slab, the framing, and the drainage, then tell you honestly whether a conversion makes sense or whether you’d be better served starting fresh. No sugarcoating, because that’s how you end up with a space you can’t actually live in come Hill Country summer.
New Detached ADU
A new detached ADU in Boerne gives you a clean sheet, and that’s often the smartest choice when the kid needs a place to land or Mom’s moving close but not too close. Detached units typically run $90,000-$220,000, depending on square footage, finishes, and how much rock the excavator hits. We site the unit for drainage and privacy, run utilities properly, and build to spec so inspections pass without hand-wringing. These are the spaces that become guest houses, rental income, or the answer to a question your family hasn’t had to ask yet.
Junior ADU & Interior Conversion
A junior ADU works within the existing footprint, often converting a large owner’s suite, bonus room, or finished attic into a semi-independent living area with its own entrance and kitchenette. For Boerne homeowners who grew up in ranch-style 78006 houses where the floor plans were built generous but dated, this can be the most practical path to multi-generational living without adding a single square foot of foundation. We also handle the plumbing, electrical, and egress upgrades that turn “a room with a fridge” into a legal, comfortable, code-compliant unit.
What happens when you call
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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 Boerne
When we build an addition or ADU in Boerne, we’re not pulling mystery materials off a van. We install brands you can look up: Simonton windows, Ply Gem siding and trim, PGT impact-rated glass where wildfire exposure or storm risk calls for it. The cedar and live oak terrain around Boerne creates real fire exposure on the edges of town, and that pushes exterior material choices toward assemblies that hold up better than what you’d spec in a flatlands suburb. We keep local stock and established supplier relationships in the area, which keeps lead times predictable and warranty claims something you’ll never have to chase alone.
Common Home Additions & ADU Problems We See in Boerne Homes
- Limestone surprises during excavation. Nearly every ground-breaking project in 78006 and 78015 risks hitting solid bedrock just inches below grade. If your contractor didn’t budget for a rock saw or pier drilling, your foundation line item is fiction.
- Drainage problems on shallow lots. Boerne channels fast-moving storm runoff through the Cibolo Creek watershed. A poorly graded addition turns the next heavy thunderstorm into a water feature inside your new room.
- Permit and aquifer compliance gaps. Land in the Edwards Aquifer Recharge or Contributing Zone carries impervious cover caps and BMP rules that standard Bexar County permitting doesn’t account for. We see out-of-area bids fall apart at plan review because nobody checked the aquifer layer.
- Older ranch homes with undersized framing or slabs. The 78006 core mixes historic German-settler structures and mid-century ranch builds. Adding a second story to a house never designed for it requires engineering, not optimism.
Pricing for Home Additions & ADU in Boerne, TX
We Also Serve Cities Near Boerne
Our crews work regularly in Boerne and the surrounding Hill Country communities. If you’re in Fair Oaks Ranch, Helotes, Timberwood Park, or Leon Valley, the same crew that builds in 78006 and 78015 can handle your addition or ADU. If your project touches the kitchen, we handle Kitchen Remodeling in Boerne as part of the larger addition, and when the powder room or owner’s bath needs work, our Bathroom Remodeling in Boerne team steps in so you’re not juggling multiple contractors.
Serving Boerne, TX - Our Local Coverage Area
We’re based in the Boerne 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 Boerne
How fast can Barrett & Sons get to my Boerne property?
We’re local enough that a site visit to most Boerne neighborhoods, including Esperanza, Napa Oaks, and the downtown 78006 core, can happen within a day or two of your call. We don’t rush the estimate, but we also don’t make you wait three weeks for a stranger to show up. Call (877) 610-1318 to set up a free walkthrough.
Do you pull permits for additions and ADUs in Boerne?
Yes, on every eligible job, permits get pulled and inspections get signed. Boerne sits partly in the Edwards Aquifer Contributing and Recharge Zones, which means the permit path often includes TCEQ and Edwards Aquifer Authority review that other contractors underestimate. We handle all of it. The inspector works for you, not for me, and I want him on the job.
What does an ADU cost in Boerne compared to San Antonio?
You’ll generally pay more in Boerne than in the flatlands. The limestone karst under the Hill Country means excavation is slower, rock saws get used, and pier drilling sometimes becomes necessary. A detached ADU that might run $90,000 on the south side of San Antonio can push toward the $220,000 range here depending on site conditions. We give you real numbers based on your actual lot, not a phone quote pulled from a spreadsheet.
Will the price change once work starts?
Not without your signature. Every scope, every allowance, every price change comes as a written change order before any work happens. If the excavator hits rock we didn’t expect, you’ll see the number in writing and approve it before the hammer hits. That’s how we’ve done it since 1998.
Do you cover all of Boerne or just certain neighborhoods?
We work across both 78006 and 78015, from the historic downtown streets to the newer master-planned subdivisions like Esperanza and Napa Oaks. If you’re within the Boerne area or the nearby communities of Fair Oaks Ranch, Helotes, Timberwood Park, or Leon Valley, give us a call at (877) 610-1318 and we’ll come take a look.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Boerne and the surrounding Hill Country since 1998.