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
If you live in Boerne and you’re weighing a home addition against an ADU, the first number you need is this: a full Home Additions & ADU project in our market typically runs $45,000 to $130,000, while a detached ADU usually lands between $90,000 and $220,000. Barrett & Sons Construction builds both, and we’ve done it here long enough to know that Boerne’s limestone doesn’t forgive guesswork. Call (877) 610-1318 and we’ll walk your property, read the rock, and give you numbers that hold up.
The honest truth about adding square footage in Boerne is that the ground under your feet decides more than your architect does. We’ve hit solid Cretaceous limestone eighteen inches below a perfectly flat lawn in Napa Oaks. That’s why we bring rock saws and pneumatic breakers to the first site visit, not just a tape measure. If you’ve talked to a contractor who quoted you a price without ever mentioning karst, you were talking to someone who hasn’t dug in the 78015 ZIP.
Why Barrett & Sons Construction Is Boerne’s Preferred Home Additions & ADU Company
Tom Barrett started this company in 1998, and his sons run crews today. That’s not marketing copy. When we say a Barrett will be on your job site, we mean it. Tom’s name and license number are published and verifiable, which matters more in a town like Boerne than any slick bid package. Ask anyone on your street, or look up the license number yourself. A live person answers our phone 24/7, and the person who answers knows the difference between Fair Oaks Ranch and the hills above Cibolo Creek, because we live twenty minutes away. If something’s wrong, we want to know about it.
Our customers in Boerne tell us two things repeatedly. First, they’ve been burned by a national outfit that quoted one price on the phone and handed them a different bill at the door. Second, they want a contractor whose name they’ll see at the hardware store on Saturday. We fit both needs. Every change order at Barrett & Sons is written before work proceeds. An allowance that isn’t on paper is a surprise waiting for a date, and we don’t do surprises. Our 90-Day Done Right Promise is written on every contract: if it’s not done right, one call brings Tom back.
Our Home Additions & ADU Services in Boerne
ADU Design & Permitting
Most of Boerne’s developable land sits within the Edwards Aquifer Contributing or Recharge Zone. That triggers TCEQ and Edwards Aquifer Authority impervious cover caps and BMP requirements that an out-of-town contractor will routinely underestimate at the bid stage. We don’t. Our ADU design work starts with drainage and impervious cover math, then moves to floor plans. The permit inspector works for you, not for me, which is exactly why I like him. We pull permits and get inspections signed on every eligible job, because the last contractor most Boerne customers used told them permits were optional.
Garage Conversion ADU
A garage conversion in Boerne runs $30,000 to $80,000, and it’s usually the smartest dollar-per-square-foot move if your existing garage slab is in good shape and your HOA allows it. Many homes in Esperanza and Napa Oaks were built with oversized attached garages on slab-on-grade foundations, which means the concrete is often already there. The catch is that Boerne’s rapid thunderstorm runoff makes proper drainage around the conversion critical. We size downspouts and grade the pad so your new living space doesn’t become a catchment basin in a Hill Country downpour.
New Detached ADU
A new detached ADU in Boerne lands between $90,000 and $220,000, and the range swings on three things: rock excavation volume, utility trench depth, and finish level. In the 78006 core, older lots often have mature oak root systems that we work around with pier drilling rather than through with a trencher. A detached unit on the Edwards Recharge Zone may need an engineered stormwater plan before we even pull the permit. We’d rather tell you that on day one than surprise you at closeout.
Junior ADU & Interior Conversion
When a separate building isn’t in the cards or the budget, a junior ADU carved out of existing square footage often makes the most sense. We convert oversized bonus rooms, enclosed porches, and underused dens into self-contained living quarters with their own entry, kitchenette, and bath. Boerne’s older ranch-style homes in the 78006 ZIP frequently have generous footprints but awkward layouts, and interior conversion lets us add value without touching exterior walls or triggering new impervious cover limits. It’s the quiet option, and sometimes the quiet option is the right one.
If your addition plans touch the existing footprint, we also handle Kitchen Remodeling in Boerne and Bathroom Remodeling in Boerne, so one crew can manage the whole scope without handoffs. The fewer contractors on your property, the fewer memos, markups, and miscommunications.
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
We build with materials you can look up, not mystery brands off a van. On window packages for ADUs and room additions, we routinely install Simonton and Ply Gem, and for Hill Country exposures with real wildfire risk, we’ve specified CGI’s Class 4-rated impact products on more than one Boerne project. The cedar and live oak terrain around Cibolo Creek makes fire-rated exterior assemblies a smarter call here than in equivalent suburban Texas markets. We keep local supply lines open with Boerne-area distributors so long-lead items don’t stall your schedule.
Common Home Additions & ADU Problems We See in Boerne Homes
- Limestone surprises at excavation: In Boerne, bedrock often sits inches below grade, not feet. Contractors who don’t plan for rock saws and breakers lowball the excavation line item and then hand over a change order the size of a car payment. We bid for rock up front, because we know it’s there.
- Drainage that ignores the Cibolo Creek watershed: Boerne channels fast, intense thunderstorm runoff through narrow draws and creeks. A poorly graded addition or ADU pad can send sheet flow toward your foundation or your neighbor’s fence line. We engineer positive drainage on every build.
- Impervious cover caps on the Edwards Aquifer zones: If your lot falls in the Contributing or Recharge Zone, you have hard limits on how much of your land can stay impermeable. Room additions, covered patios, and ADU pads all count. We bring compliant BMP designs to permitting so the Edwards Aquifer Authority doesn’t kick your plans back.
- Older 78006 homes with slab and foundation quirks: The historic core of Boerne mixes ranch-style slab homes with German-settler-era structures that occasionally need mid-century foundation work before an addition can tie in. We assess existing footings and grade beams honestly, in writing, before you sign a contract.
Pricing for Home Additions & ADU in Boerne, TX
A whole home addition in Boerne runs $45,000 to $130,000. A garage conversion lands between $30,000 and $80,000. A new detached ADU starts around $90,000 and goes to $220,000 depending on rock excavation, utility runs, and finishes. Those are real ranges, not clickbait. What moves the needle here more than any other market we serve is subsurface rock. A lot in the 78015 subdivisions might need minimal rock work, while a build on the karst ledges above the 78006 corridor can add weeks and five figures in pier drilling. We price for the ground, not just the floor plan.
Two things keep our numbers honest. First, scope in writing, allowances in writing, change orders in writing. Second, fixed-bid pricing on the contract, so the bottom line doesn’t drift because someone forgot a line item. Call (877) 610-1318 for a free estimate. We’ll walk the site, read the rock, and give you a quote that means something.
We Also Serve Cities Near Boerne
Beyond Boerne, our crews regularly build in Fair Oaks Ranch, Helotes, Timberwood Park, and Leon Valley. Each of those towns has its own permitting quirks and soil conditions, and we know them the same way we know Boerne. If you’re just outside the city line, Home Additions & ADU in Boerne coverage extends to you. One crew, one phone number, one name on the truck.
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
We’re typically able to schedule a site walk within a few business days of your call, and our crews stage Boerne projects on a rolling schedule throughout the year. If you’ve already got plans, we’ll move faster. If not, we’ll help you get from concept to permit-ready drawings. Call (877) 610-1318 and we’ll give you a real start window after we see the site.
Yes. We work in Esperanza, Napa Oaks, the 78015 corridor, and the historic 78006 core, along with Fair Oaks Ranch, Helotes, Timberwood Park, and Leon Valley. Whether you’re on a ranch-style lot near Cibolo Creek or in a master-planned subdivision off Ranger Creek Road, we know the terrain and the permitting path.
A detached ADU in Boerne runs $90,000 to $220,000, which is typically 10 to 20 percent more than a comparable flatlands build in San Antonio. The difference is limestone excavation, Edwards Aquifer impervious cover compliance, and sometimes pier drilling that flatland builders never see. Call (877) 610-1318 for an exact quote, and we’ll show you the rock report that backs our numbers.
Only if the scope changes, and only in writing. Every change at Barrett & Sons is a written change order issued before work proceeds. You’ll sign off on the number before a single nail moves. No surprise invoices at the end. That’s the whole point of an allowance that’s on paper.
Yes. Every job we complete is backed by our 90-Day Done Right Promise, written on the contract. If something’s not done right, one call brings Tom back. We also offer a $40 Off Any Repair Over $200 offer and a Free Second Opinion on Any Written Estimate, along with a permanent 10% Senior & Veteran discount for Boerne homeowners who qualify.
Ready to talk square footage, setbacks, and stone? Call Barrett & Sons Construction at (877) 610-1318. We’ll give you honest numbers, a written scope, and a name you can verify. Free estimates, no trip charge inside the county, and a live person on the other end of the line.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Boerne and the surrounding Hill Country. Local roots, on time, community first, accountable, loyal.