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 Brushy Creek
Home additions and ADU construction in Brushy Creek typically runs $45,000 to $130,000 for a room addition, and $90,000 to $220,000 for a new detached ADU. The work usually takes three to six months depending on scope, Williamson County inspection scheduling, and HOA review windows. We answer our own phone at (877) 610-1318, and we’ll give you a written, line-item estimate before you decide anything. This page covers what Brushy Creek homeowners need to know about expanding their home here in 78717, where county permits, Blackland Prairie clay, and HOA rules shape every project.
Why Barrett & Sons Construction Is Brushy Creek’s Preferred Home Additions & ADU Company
We’ve done enough additions in Brushy Creek to know that the neighborhood’s age range, the unincorporated status, and the soil underneath all matter. Tom Barrett started Barrett & Sons Construction in 1998, and his sons run the crews. When you call us about a garage conversion off Hairy Man Road or a room addition near Cat Hollow Park, the person who answers is someone who knows what those streets look like. No voicemail maze, no out-of-state call center.
Permits here are different. Brushy Creek has no city building department. Pulling through Williamson County means navigating their processes, and we handle that start to finish. Our Home Additions & ADU team files the paperwork, schedules the inspection windows, and stands there when the inspector arrives. If you want to verify who we are, Tom publishes his name, his address, and his license number. Look it up.
We also carry the 90-Day Done Right Promise on every contract. If something isn’t right after we finish your Brushy Creek project, Tom comes back and makes it right. One call.
Our Home Additions & ADU Services in Brushy Creek
ADU Design & Permitting
Designing an ADU in Brushy Creek means designing around Williamson County’s permit process, not a city hall. We start every project by checking zoning setbacks for your specific lot in the 78717 ZIP, then we handle the county submittal package. For the newer subdivisions, we also file the HOA architectural review at the same time so one doesn’t stall the other. A well-run Brushy Creek ADU project has the county and the HOA moving in parallel from day one.
Garage Conversion ADU
Garage conversions are the most popular ADU route in Brushy Creek because the master-planned community’s lots are generally tight, and the attached garage already sits on the post-tension slab. You don’t pay for new foundation work, which keeps the typical Brushy Creek garage conversion between $30,000 and $80,000. But you must evaluate slab condition first. Blackland Prairie clay moves, and a slab that has heaved even a half inch changes how we frame and finish.
New Detached ADU
A new detached ADU in Brushy Creek starts somewhere around $90,000 and can reach $220,000 depending on size, finishes, and utility trenching. Trenching across expansive clay without a soils report is how new slabs heave away from the main structure within two years. We spec the soils work before we ever open a trench, and we write every allowance and change order so there’s no invoice surprise at the end.
Junior ADU & Interior Conversion
A junior ADU carved from existing interior square footage often costs far less than new construction. In Brushy Creek’s two-story brick-veneer homes from the 1990s and 2000s, that usually means reworking a first-floor bedroom suite, a formal dining room, or a bonus room over the garage. We route new rough-in plumbing carefully around post-tension cables, and we pull the same Williamson County permits as we would for a full addition.
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 Brushy Creek
We install brands you can look up, not mystery materials off a van. For Brushy Creek projects, we regularly spec Simonton windows for sunrooms and enclosed patios, and Ply Gem or PGT when the project calls for high-performance glazing that can handle Central Texas heat. We carry the local inventory and parts access that keep a Brushy Creek job moving when a window arrives damaged or a trim piece doesn’t match. You’ll see the brand name on the product and on the invoice.
Common Home Additions & ADU Problems We See in Brushy Creek Homes
- Slab heave under additions. Brushy Creek sits on Blackland Prairie clay that shrinks in drought and swells in deluge. Additions that don’t account for that movement crack at the seam where new meets old. We evaluate slab conditions before design so your addition doesn’t separate within two years.
- HOA architectural review surprises. Several Brushy Creek subdivisions enforce roof pitch, sight-line, and material rules. The time to file is before county permits, not after. We’ve seen projects get county approval and then get rejected by the HOA because nobody checked the architectural covenant first.
- Permit timeline mismatches. Brushy Creek has no city inspector. Williamson County inspectors cover wide territory, and a rough-in appointment can be ten business days out during spring. That delay alone can stall framing, drywall, and finish trades. We schedule inspection windows at contract signing, not after demo.
- Builder warranty confusion. Many Brushy Creek homes from the 1993 to 2008 build wave still carry or recently carried structural warranties. A poorly planned cut into a post-tension slab can void them. We design around those cables and document everything so your warranty stays intact.
Pricing for Home Additions & ADU in Brushy Creek, TX
Real numbers, not vague ranges. A room addition in Brushy Creek typically runs $45,000 to $130,000 depending on square footage, foundation work, and whether you’re adding a bathroom. A garage conversion ADU lands between $30,000 and $80,000 because the shell already exists. A new detached ADU starts around $90,000 and can pass $220,000 for a larger unit with a full kitchen and upgraded finishes. Scope in writing, allowances in writing, change orders in writing. That’s how we quote, and that’s how we bill.
| Project Type | Typical Brushy Creek Range |
|---|---|
| Home Addition | $45,000 – $130,000 |
| ADU Construction | $90,000 – $220,000 |
| Garage Conversion | $30,000 – $80,000 |
What moves the number? Foundation condition, HOA-required materials (stone veneer over brick, for example), distance from the existing utility panel, and whether Williamson County requires a soils report. All of that goes in your written estimate. Call (877) 610-1318 and we’ll walk through it with you.
We Also Serve Cities Near Brushy Creek
Our crews serve Anderson Mill, Jollyville, Cedar Park, and Wells Branch too. Same written pricing, same county-level permitting expertise. If you’re just outside the 78717 ZIP and want to talk additions or an ADU, our Brushy Creek team covers that whole corner of Williamson County.
Serving Brushy Creek, TX - Our Local Coverage Area
We’re based in the Brushy Creek 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 Brushy Creek
Yes. Enclosing a patio into a sunroom is a structural change, which means Williamson County requires a permit even though Brushy Creek has no city building department of its own. The permit process covers the new roofline, the glazing, and the electrical rough-in. We file the county permit and the HOA review together so your sunroom doesn’t stall waiting on either one. Call (877) 610-1318 and we’ll confirm exactly what your specific patio enclosure needs.
You can, but only if the work avoids cutting into post-tension cables and any structural warranty work is documented. The slab in your Brushy Creek home is likely post-tension concrete. A blind cut can hit a tension cable, and that voids more than a warranty. We locates the cable map, designs around it, and routes new plumbing through an exterior chase instead of through the slab. Your warranty stays intact and the county gets a clean set of drawings.
The big ones are roof pitch, sight-line setbacks, and exterior material requirements. Some Brushy Creek subdivisions restrict second-story massing so it doesn’t block a neighbor’s sight line. Others require the addition to match the original brick veneer exactly. We pull your community’s architectural covenant before design starts, so you don’t pay for drawings an HOA committee will reject. Get the HOA package first, then we design. Call (877) 610-1318 for a free review of your specific subdivision rules.
You book the rough-in inspection at contract signing, not after demo. Williamson County inspectors cover wide rural-to-suburban territory, and Brushy Creek jobs don’t get priority. During spring and early summer, a rough-in appointment can be ten business days out. If you wait until the plumbing is ready, your crew stands idle for two weeks. We schedule every staged inspection as a date on the contract, and we adjust the construction calendar around the county’s timeline before a single wall opens.
Most Brushy Creek homes from that era need $10,000 to $30,000 in quiet upgrades first: original builder HVAC, aging water heaters, and single-pane windows that leak cooled air all July. The window replacement alone often runs $4,500 to $15,000, depending on glazing and brand. We’d rather tell you what your home actually needs than sell you an addition that a failing system turns into a regret. Call (877) 610-1318 and we’ll walk your 2005 house room by room with you. Free estimate, no trip charge inside the county.
Get a Written Estimate for Your Brushy Creek Project
If you’re in Brushy Creek and you’re considering an addition, a garage conversion, or a full ADU, we’d like to see your lot, your slab, and your HOA package. We’ll write you a line-item estimate, file the right permits, and stand behind the work with the 90-Day Done Right Promise. Tom Barrett and his sons are on the job most days. Call (877) 610-1318 to schedule your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Brushy Creek since 1998.