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 Hornsby Bend
Home additions in Hornsby Bend run $45,000 to $130,000, and ADU construction runs $90,000 to $220,000. That’s the honest range Tom Barrett quotes when he walks your property, and it’s the range that holds once the walls are open. If you live in the 78725, you already know your land sits in the Colorado River floodplain, and that single fact changes everything about how an addition gets permitted, engineered, and built here. Call (877) 610-1318 and Tom will walk the site with you, check the elevation, and tell you straight what your project needs before you spend a dime.
Why Barrett & Sons Construction Is Hornsby Bend’s Preferred Home Additions & ADU Company
Tom Barrett started Barrett & Sons Construction in 1998, and his sons run the crews. That means when you call about a room addition off FM 969 or a detached ADU near the river bottom, the person who answers is someone whose name is on the truck. We answer the phone 24/7; you don’t get a voicemail box or an out-of-state call center.
We’ve pulled permits in the 78725 long enough to know that Travis County treats this bend of the Colorado differently than it treats upland Austin. A Hornsby Bend addition isn’t a copy-paste of an Austin slab job. The floodplain rules, the expansive clay, the elevation certificates - we schedule all of it before framing starts, not after the inspector asks for it. Ask anyone on your street, or look up Tom’s license number yourself. He publishes his name, address, and license number because he wants you to check.
Our Home Additions & ADU Services in Hornsby Bend
ADU Design & Permitting
An ADU in Hornsby Bend starts with the floodplain, not the floor plan. We check whether your lot falls in FEMA Flood Zone AE, order the Elevation Certificate from a licensed surveyor, and design the finished floor height above Base Flood Elevation before we draw a single wall. The county will not issue a Certificate of Occupancy without that surveyor-stamped certificate, and we don’t wait until the end to schedule it.
Garage Conversion ADU
Many garages in the 78725 were built before modern floodplain enforcement, and the slab is often just a few inches above grade. That means a straightforward conversion can turn into a floodproofing requirement the moment the county sees the plans. We walk the garage with you first, measure the slab against BFE, and tell you honestly whether the project is a simple conversion or a regulated one. In Hornsby Bend, garage conversions typically run $30,000 to $80,000, and the floodplain status of your slab is the biggest variable.
New Detached ADU
New construction here means flood-vent-compliant foundations, over-excavated footings through the silty clay, and finished floors set high enough to satisfy Travis County. We build detached ADUs from $90,000 to $220,000 in Hornsby Bend, and the price reflects what the soil and the floodplain actually require, not what a national estimator assumes from a satellite photo. KraftMaid cabinets and Schluter waterproofing are standard choices, and they hold up to the humidity cycles this river bottom throws at them.
Junior ADU & Interior Conversion
A junior ADU inside an existing home can bypass some site work, but if your house predates floodplain enforcement, the conversion may still count toward the 50% substantial improvement threshold. We review the appraised value, total the scope, and tell you before we bid whether the county will treat it as a simple remodel or a floodplain compliance project. For older Hornsby Bend homes, the answer is often the latter, and knowing that up front is worth the inspection.
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 Hornsby Bend
We install Schluter waterproofing systems in every wet area, and we specify GAF roofing on any addition that ties into the existing roof line, because the humidity and river-bottom exposure here punishes cheap underlayment. We don’t stock mystery brands off a van, and Hornsby Bend homeowners can look up every material we quote before they sign. For a Home Additions & ADU project, materials matter less than the floodplain engineering underneath them, but we use brands that won’t embarrass either of us when the inspector walks through.
Common Home Additions & ADU Problems We See in Hornsby Bend Homes
- Framing compromised by decades of hidden roof leaks. Our crew opened up a 1970s ranch on Gilbert Road for a second-story addition and found load-bearing studs too rotted to reuse and cloth-wrapped wiring with no ground. We pulled the permit, brought in a structural engineer, and wrote every repair into a change order before closing a wall.
- Slabs that sit below Base Flood Elevation. Many existing structures in the 78725 were built before FEMA flood maps were enforced, so an addition that crosses the 50% threshold triggers floodproofing the owner never budgeted for. We check the elevation on day one.
- Expansive alluvial clay that heaves footings. The Colorado River bottom soils here swell and shrink through every Central Texas wet-dry cycle. Standard pier-and-beam footings crack within two seasons unless they’re over-excavated and stabilized. We dig deeper than the standard Austin spec because this ground demands it.
- Wiring and panel upgrades hiding behind the drywall. Older Hornsby Bend homes often need a panel replacement and grounding fixes the moment the walls come open. We write those allowances into the contract up front, so the cost doesn’t arrive as a surprise invoice at the end.
Pricing for Home Additions & ADU in Hornsby Bend, TX
| Project Type | Hornsby Bend Price Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
| Second Story Addition | $45,000 - $130,000 |
| ADU Site Prep & Utilities | $90,000 - $220,000 |
Those are Hornsby Bend numbers, not Travis County averages. The floodplain drives the variance more than anything else. A detached ADU on a lot that sits comfortably above BFE will land toward the low end; the same ADU on a low slab with expansive clay and an elevation certificate requirement will push toward the high end. We quote after we walk the site and pull the flood map, not before. Call (877) 610-1318 and we’ll give you a free written estimate with a complete line-item scope, and every change order in writing before any scope change touches the job.
We Also Serve Cities Near Hornsby Bend
Our Home Additions & ADU team covers Hornsby Bend and the surrounding communities: Austin, Manor, Pflugerville, and Wells Branch. Dispatch and scheduling are coordinated from our Austin office, but the crews who serve Hornsby Bend know the 78725 floodplain rules because they work here regularly, not because they read about them in a permit manual.
Serving Hornsby Bend, TX - Our Local Coverage Area
We’re based in the Hornsby Bend 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 Hornsby Bend
It depends on the appraised value of your home and the total cost of the addition, including finishes and any mechanical work. If the project cost equals more than 50% of the structure’s market value, Travis County treats it as a substantial improvement and requires floodplain compliance measures like an Elevation Certificate and flood vents. We calculate this threshold before we quote so you know exactly where you stand. Call (877) 610-1318 for a free assessment.
Because Hornsby Bend sits almost entirely within FEMA Flood Zone AE, Travis County requires a surveyor-stamped Elevation Certificate confirming your lowest finished floor clears Base Flood Elevation before it will issue a Certificate of Occupancy for new construction or substantial improvements. We schedule the surveyor early so the certificate doesn’t hold up your final inspection.
Possibly, but the county may require floodproofing if the finished floor sits below Base Flood Elevation and the project crosses the substantial improvement threshold. In some cases, a garage conversion is better approached as a tear-out and rebuild with an elevated slab. We’ll measure the slab against the flood map before you commit, and give you an honest answer with numbers attached. Call (877) 610-1318 to schedule a site walk.
We build inspection allowances into the contract in writing, and any repair scope that exceeds the allowance becomes a written change order before we touch it. When we found rotted load-bearing studs and cloth-wrapped wiring in a Gilbert Road ranch, we brought in a structural engineer, wrote the repair scope, and got the owner’s signature before closing the wall. The permit inspector works for you, not for us, and we like it that way.
If the sunroom is enclosed and conditioned space, and the total project cost pushes past the 50% threshold, yes - Travis County will likely require flood vents and an Elevated finished floor. Open patio enclosures that don’t meet the definition of living space may not trigger the requirement, but we don’t guess. We check the flood map and the current code interpretation before we draw plans. Call (877) 610-1318 and we’ll tell you exactly what applies to your lot.
Get Your Free Hornsby Bend Estimate
If you’re thinking about a room addition, a second story, or an ADU on your Hornsby Bend property, start with a conversation, not a contract. Tom Barrett will walk your lot, pull the flood map, check your existing foundation, and tell you plainly what the county will require and what it will cost. You’ll get a written line-item estimate, no trip charge inside the county, and a permanent 10% senior and veteran discount. Call (877) 610-1318 today to schedule your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Hornsby Bend since 1998.