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 Lakeway
Most Lakeway homeowners call us after realizing their lot fights back. The same limestone that gives you those Hill Country views also means your addition will likely need rock excavation, drilled piers, or an engineer’s stamp before a foundation gets poured. A home addition in Lakeway typically runs $45,000-$130,000, and an ADU from $90,000-$220,000 depending on slope, utilities, and tree protection. Barrett & Sons Construction has done this work across Lakeway long enough to know where the rock sits, who to call at the city, and what the inspector will flag. Call (877) 610-1318 and we’ll walk your lot with you before anyone starts drawing lines.
Why Barrett & Sons Construction Is Lakeway’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998, and he still answers the phone. His sons run the crews. That matters when you’re about to spend six figures on an addition and you want to know whose name is on the permit. We pull every permit, sign off on every inspection, and put every price change in writing before work moves. No surprises at the end. No voicemail box when you call at 7 a.m. with a question about your foundation.
Lakeway is not an easy place to build. The hills, the rock, the live oaks, and the Lake Travis watershed all have opinions about what gets built where. We respect that. It’s why homeowners here tend to ask around before hiring for Lakeway Roofing or any major project, and why our name comes up. The permit inspector isn’t our adversary. He works for you. When he passes a Barrett & Sons job, it’s because we did the work the way Lakeway expects it done.
When you call (877) 610-1318, you get a live person. Not a call center. Not a recording. You get pricing with scope in writing, allowances in writing, and change orders in writing. And every job carries the 90-Day Done Right Promise. If it’s not done right, Tom comes back.
Our Home Additions & ADU Services in Lakeway
ADU Design & Permitting
An ADU in Lakeway is not a backyard shed. Between LCRA waterfront setbacks if you’re near the lake, impervious cover caps for the watershed, and the heritage tree ordinance, the design and permitting phase can take longer than the framing. We handle the full package: site evaluation, arborist coordination when protected oaks are involved, engineer-stamped foundation plans, Windows & Doors - Lakeway included if needed, and the permit package the city wants to see. You shouldn’t have to learn Lakeway’s land development code to add a guest house. That’s our job.
Garage Conversion ADU
Converting an attached garage is usually the smartest money in Lakeway, because the foundation and roofline already exist. You’re not drilling into new rock. But you are dealing with the question of what to do with your cars, and whether the existing slab can handle the plumbing changes an ADU requires. We’ve done enough garage conversions in the 78738 area to know when a simple conversion works and when the slab tells us to slow down and re-engineer. We’ll tell you the truth before you spend a dollar.
New Detached ADU
A detached ADU on a sloped, rocky Lakeway lot means new utilities, new foundation, and likely a retaining wall or two. We build these from the ground up with the same care as a primary residence, because the same building code applies. You’ll get a hard number on what rock excavation will cost, not a vague “site work allowance” that shows up later as a surprise. An allowance that isn’t on paper is a surprise waiting for a date. Ours is on paper, before the first cut.
Junior ADU & Interior Conversion
A JADU inside your existing home, like a finished bonus room with a kitchenette and separate entrance, is the most budget-friendly way to add housing in Lakeway without touching your footprint. It also keeps you clear of the impervious cover debate entirely. We’ve built these into existing Lakeway homes where a grown child needed independence or a parent needed to be close. It’s a lighter project, but we apply the same permit and inspection standard.
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 Lakeway
On the hardscape side of an ADU or sunroom project, we install Belgard and Techo-Bloc pavers, plus Cambridge Pavers when the design calls for a specific tone. We don’t put mystery materials on your lot. You can look up every brand we carry and read the manufacturer specs yourself. For Lakeway especially, the paver selection matters because of drainage. A well-built paver patio or walkway can help move water off your sloped lot, and these brands hold up to Hill Country heat without fading. We stock locally for Lakeway jobs, so material delays don’t stall your project.
Common Home Additions & ADU Problems We See in Lakeway Homes
- Rock where the addition goes. Most Lakeway lots sit on Edwards Plateau limestone. Digging a foundation trench two feet down often means hammering out solid rock or calling in an excavator with a breaker. If your builder didn’t price for that, the number changes fast. We price for it because we expect it.
- Heritage live oaks in the build zone. Lakeway’s tree ordinance protects large oaks, often 24-inch caliper and up. Disturbing the protected root zone mid-dig can trigger a stop-work order. We bring in an arborist early and design around the tree, not through it.
- Impervious cover limits. Because Lakeway sits in the Lake Travis watershed, the city caps how much of your lot can be covered by roofs, driveways, and patios. Adding square footage can push you past the limit and require stormwater engineering. We run that math in the planning phase, before you’re committed.
- Sloped cut-and-fill lots. Many Lakeway homes are built into hillsides. An addition on the downslope side often needs a retaining wall, drilled piers, or both. Existing walls age, too. We inspect what’s already there before we design anything new, because a failing wall under a new addition is a problem you should never discover after framing starts.
Pricing for Home Additions & ADU in Lakeway, TX
Home additions in Lakeway run $45,000-$130,000. A detached ADU starts around $90,000 and can reach $220,000 on a difficult hillside lot with rock excavation, utilities trenching, and stormwater engineering. A garage conversion is typically $30,000-$80,000 because you’re working inside existing walls. Those ranges reflect real Lakeway conditions: limestone, slope, protected oaks, and watershed rules all add cost that a flat-lot Austin builder never quotes for.
What moves the number: site access for equipment, rock excavation depth, whether the city requires an arborist report, and how far your new ADU sits from existing water and sewer lines. You’ll get a free estimate from us with the scope in writing. Call (877) 610-1318 and we’ll put numbers on it. No trip charge inside the county, and a free second opinion on any written estimate you already have.
We Also Serve Cities Near Lakeway
Our crews regularly work in Bee Cave, Lago Vista, and Shady Hollow, and we’re familiar with how the building rules change as you move around the Lake Travis area. We also do Kitchen Remodeling in Lakeway and Bathroom Remodeling in Lakeway for homeowners taking on a larger whole-home project. If you’re in Austin and shopping contractors for any of this work, call us. We’ll tell you honestly whether your job is in our wheelhouse.
Serving Lakeway, TX - Our Local Coverage Area
We’re based in the Lakeway 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 Lakeway
A home addition in Lakeway typically costs $45,000-$130,000. The wide range comes down to your lot: rock excavation, slope, retaining walls, protected oaks, and impervious cover requirements all push the number. A flat-lot sunroom is at the low end. A second-story addition with engineered piers is at the high end. Call (877) 610-1318 for an exact quote on your lot. Estimates are free.
Yes, we prepare and submit the full ADU permit package to the City of Lakeway, including any required arborist reports for protected live oaks and stormwater documentation for impervious cover compliance. We coordinate with LCRA when waterfront setbacks apply. You won’t be handed a set of plans and told to figure out the permit process yourself.
A detached ADU in Lakeway usually takes 8 to 14 months from design to final inspection, with permitting often consuming the first 2 to 3 months due to tree surveys, engineering, and LCRA or city review. A garage conversion moves faster because the shell already exists. We give you a written timeline before work starts, and we update it if the city or weather changes the schedule. For a specific timeline on your project, call (877) 610-1318.
Yes, we work throughout Lakeway and the 78738 zip code, including the older custom-home pockets near Lake Travis and the newer construction on the hills. We’re local to the area and know the streets, the soil, and the inspectors. If you’re off Rough Hollow Drive or near the Yaupon golf course area, we’ve likely been on a job nearby.
Every Barrett & Sons Construction job carries the 90-Day Done Right Promise, written on the contract. If something isn’t done right, Tom comes back and makes it right. One call to (877) 610-1318. Workmanship issues that show up after final inspection are handled the same way: we fix them.
Call (877) 610-1318 today. We’ll walk your Lakeway lot, talk honestly about what your addition or ADU will take, and give you a written estimate with the scope in writing. Tom still answers the phone. His sons still run the crews. And the price we quote is the price you’ll see when the job is done.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Lakeway and the surrounding Hill Country since 1998.