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 Georgetown
A home addition or ADU in Georgetown, Texas typically runs $45,000 to $130,000 for a room addition and $90,000 to $220,000 for a detached ADU, with garage conversions landing between $30,000 and $80,000. Most projects take 3 to 7 months once permits clear, and the single biggest variable in Georgetown is what’s under your slab: limestone ledge on the west side or expansive clay on the east. Barrett & Sons Construction has been building in this market since 1998, and we know exactly which neighborhoods send a rock hammer through a bid. Call (877) 610-1318 when you’re ready to talk real numbers.
We’re not a franchise dispatching strangers to your door. Tom Barrett’s name is on every contract, his sons run the crews, and every permit gets pulled before a single nail moves. If you’re weighing an addition over a move, this page explains what it actually costs here, what a permit triggers, and what we’ve found inside Georgetown homes when walls come open.
Why Barrett & Sons Construction Is Georgetown’s Preferred Home Additions & ADU Company
We’ve been the name-on-the-truck alternative in Williamson County for over 29 years as a company, founded in 1998 and owner-operated from day one. When a Georgetown homeowner calls, Tom Barrett or one of his sons answers. Not a call center. Not a voicemail that goes to an out-of-state office. You’ll see us at the hardware store on a Saturday, and if something isn’t done right, the 90-Day Done Right Promise means one call brings Tom back.
Our Home Additions & ADU team has worked inside Sun City Texas garage conversions, second-story additions over limestone homes near the courthouse square, and new detached ADUs in Wolf Ranch and Morningstar. That local exposure matters when a bid needs a rock-breaking line item in 78628 or a slab engineer who understands Vertisol clay movement east of I-35. We carry premium brand materials you can look up yourself: Techo-Bloc and Cambridge Pavers on hardscapes, Andersen and Marvin windows where openings change, GAF and CertainTeed on roofing tied into new framing. Permits pulled on every eligible job. Inspections signed. Every price change arrives as a written change order before any work proceeds. An allowance that isn’t on paper is a surprise waiting for a date.
Our Home Additions & ADU Services in Georgetown
We build additions and ADUs across Georgetown’s 78626, 78627, 78628, and 78633 ZIP codes, with three services that matter most in this market: garage conversions, ADU site prep and utilities, and second-story additions. Here’s how each one actually plays out here.
Garage Conversion ADU
A garage conversion in Georgetown costs $30,000 to $80,000, and the homes in Sun City Texas are a perfect example of why the range exists. Those Del Webb builds from the early 2000s are now 20-plus years old, and opening the wall shared with the laundry often reveals wiring that no longer meets code once it’s exposed. We plan for that before we bid: inspection first, allowances written into the contract, and any surprise priced and approved on paper before we touch it. In a Georgetown garage conversion, you’re also dealing with the original slab, which in Sun City can sit on clay that’s moved over two decades of wet-dry cycles. We check for cracks and settle before framing starts.
New Detached ADU
A new detached ADU in Georgetown runs $90,000 to $220,000, and the geology of your lot drives a big piece of that number. On the west side in 78628, limestone ledge can appear at 18 to 24 inches below grade, and utility trenching, footers, and even landscape grading often require a rock-breaking line item that builders 15 miles east in Round Rock never quote. We write that line item into your initial bid, not as a surprise later. Techo-Bloc or Cambridge pavers for the patio and walkway come from our local suppliers, so the finished ADU looks like it belongs on your street, not like a kit dropped from a catalog.
Junior ADU & Interior Conversion
A junior ADU inside your existing Georgetown home keeps the exterior footprint untouched while turning a section of the house, often a large primary suite or a bonus room with its own entrance, into an independent living space. This works well in Sun City Texas, where HOA rules often lean on footprint and setback restrictions. Interior conversions also trigger far less site work, which matters on Georgetown’s clay-heavy east side where slab movement is already a concern. A junior ADU means one smaller foundation to worry about, and the work happens mostly indoors.
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 Georgetown
We don’t install mystery brands off a van. When your addition or ADU calls for hardscape, site walls, or a patio that ties the new structure to the house, we specify Techo-Bloc and Cambridge Pavers, with Quikrete and Oldcastle products where footings, curbs, and utility bedding are involved. These are names your landscaper and your engineer both recognize, and our crews are set up to work with them efficiently. That means less waiting on materials, which matters when an inspection is scheduled and you want the project moving.
Common Home Additions & ADU Problems We See in Georgetown Homes
Here’s what Georgetown actually throws at a project, from our own jobs:
- Limestone ledge on the west side. In neighborhoods across 78628, caliche and solid rock sit 18 to 24 inches down. A bid that doesn’t include rock excavation for ADU footers and utility trenches is a bid that’s going to grow. We price it up front, because we’ve dug these lots before.
- 2000s Sun City wiring and framing behind the drywall. Del Webb homes built around 2004 and 2005 dominate 78633. Once you open a wall for a garage conversion, you’re likely to find Romex that doesn’t meet current code at the point of exposure, plus headers undersized for today’s clear-span requirements. The permit inspector works for you, not for me, and he’s going to flag it. So do we, in writing, before work starts.
- Expansive clay soil under new slabs. Georgetown sits at the edge of the Edwards Plateau, and the east side’s Vertisol and clay soils heave and contract hard through our drought-wet cycles. A new detached ADU on an under-engineered slab cracks footers and throws doors out of square within the first couple of seasons. We engineer for the movement, not against it.
- Historic fabric near the courthouse square. Georgetown’s late-19th-century limestone homes and commercial buildings need more than standard framing knowledge when you’re adding a second story or cutting a new opening. The stone is soft, the mortar is lime-based, and the structural logic is different from a 2018 production build. We’ve done it, and we know when to bring in a masonry specialist.
Pricing for Home Additions & ADU in Georgetown, TX
Here are straight line-item ranges for Georgetown’s market, not national averages:
| Project | Georgetown Price Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
What moves your number? Rock excavation on west-side lots, soil engineering on east-side clay, the condition of 20-year-old framing and wiring once walls open, and whether your project is a single-room addition or a full second-story with living space below. Every scope, every allowance, every price change arrives as a written change order before work proceeds. No surprise invoices at the end. Call (877) 610-1318 for a free estimate built for your specific Georgetown lot, not a formula from another state.
We Also Serve Cities Near Georgetown
While this page is focused on our Georgetown work, we also take projects in the surrounding communities of Round Rock, Brushy Creek, Cedar Park, and Hutto. The geology shifts fast in this corridor, and our rock and clay experience carries from one side of the county line to the other. If you’re just outside Georgetown, call and ask; we’ll tell you straight whether we serve your street.
Serving Georgetown, TX - Our Local Coverage Area
We’re based in the Georgetown 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 Georgetown
Rock excavation for a detached ADU on Georgetown’s west side typically adds $3,000 to $8,000 to the site prep line, depending on how much limestone ledge your lot has and how deep the footers and utility trenches need to go. At 18 to 24 inches, we’re usually looking at a rock hammer from day one. Call (877) 610-1318 and we’ll give you a written line item, not a guess.
A 2004 Sun City garage conversion will typically trigger electrical upgrades (GFCI and AFCI protection, grounded circuits), smoke and carbon monoxide detectors tied to current placement rules, insulation requirements at exterior walls, and structural review of any header we expose. If the original wiring has degraded or the framing undersized, those become written change orders before we proceed. That’s exactly what happened last spring on a Sun City job when our crew found crumbling Romex and an undersized header: we wrote the change order, updated the permit drawings, and got inspection sign-off before drywall went back up.
Yes, we pull permits and coordinate inspections on every eligible second-story addition in Georgetown’s historic core. Historic limestone homes near the Williamson County Courthouse square often require additional review, and we work with the city’s process rather than around it. That’s how we’ve always operated: permits pulled, inspections signed, every time.
East of I-35 near the San Gabriel River, Georgetown’s clay soils heave and contract through severe wet-dry cycles, so any new room addition needs a foundation engineered for expansive soil movement, not a standard slab spec. Expect a soils report and possibly deeper piers or reinforced slab details. We factor that into the bid up front because ignoring it means cracked footers and misaligned doors within the first drought cycle.
Yes, a junior ADU inside a Sun City Texas home keeps the exterior footprint unchanged while converting an existing wing, bonus room, or parts of the main level into independent living space with its own entrance, kitchenette, and bath. This approach often simplifies HOA approval and avoids the soil and rock site work a detached ADU requires. Pricing reflects the smaller scope and nearly all-indoor work.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Georgetown since 1998.