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 Alief
Home additions and ADUs in Alief typically run $45,000-$130,000 for a full addition and $90,000-$220,000 for a new detached ADU. Those numbers reflect real costs of building in unincorporated Harris County, where permits come from Harris County Engineering, not Houston. At Barrett & Sons, we’ve spent 29 years learning what Alief’s 1970s slab-on-grade homes demand before walls come down. Call (877) 610-1318 to schedule a free estimate and get your project scoped in writing before you commit to anything.
Why Barrett & Sons Construction Is Alief’s Preferred Home Additions & ADU Company
Alief homeowners call us because we know the difference between a Houston permit and a Harris County permit before it costs them two weeks of schedule. Tom Barrett founded this company in 1998, and his sons run the crews that show up at your door. When we walk a 1979 ranch over near Brays Bayou, we already know what’s likely behind those brick veneer walls: undersized joists, ungrounded wiring, and slab cracks from Beaumont clay that’s been moving for forty years. That’s not a guess. It’s what we see on nearly every opening we do in Alief.
Every scope, every allowance, every price change arrives as a written change order before work happens. The permit inspector works for you, not for us, which is exactly why we like him. And when the job’s done, the 90-Day Done Right Promise means one call brings Tom back to make it right. Ask anyone on your street, or look up the license number yourself. We answer our own phone.
Our Home Additions & ADU Services in Alief
ADU Design & Permitting
ADU design in Alief starts with Harris County Engineering, not the Houston Permitting Center. That single fact trips up contractors who work Houston proper and file in the wrong jurisdiction, losing two weeks before the foundation inspection can even be scheduled. We handle the complete permit package, including flood-plain review if your lot falls within the Brays Bayou watershed, and we walk the plans through Harris County’s separate fee schedule and inspection workflow before we ever put a shovel in the ground.
Garage Conversion ADU
Garage conversions are the most common ADU we build in Alief, because the 1970s and 1980s stock has attached garages that convert cleanly when the slab is sound. But “when the slab is sound” is the operative phrase. Hairline cracks from decades of Beaumont clay movement are common, and we inspect before we quote. A garage conversion ADU in Alief typically runs $30,000-$80,000, depending on whether we’re adding a bathroom, a kitchenette, or just a finished living space with its own entrance.
New Detached ADU
A new detached ADU in Alief runs $90,000-$220,000 and requires a full Harris County foundation inspection, which means soil testing for expansive clay before we pour. The flat, low-lying terrain here means drainage has to be engineered, not assumed. We design each detached ADU to handle the May-September heat load with proper insulation and mechanical sizing, and we build the roof assembly for a defined Gulf storm season that can stall exterior work if you don’t plan around it.
Junior ADU & Interior Conversion
Junior ADUs convert existing interior space, like a master suite wing or a formal dining room, into a self-contained unit with its own entrance, kitchenette, and bath. In Alief’s brick-veneer ranch homes, these projects often trigger code upgrades the moment walls are open: new ground-fault circuits, smoke and CO detectors, and egress window retrofits. We write those into the contract as allowances, so you see every number in writing before we touch a wall.
We’re also the team to call for Home Additions & ADU projects that go beyond ADUs: room additions, second-story additions, and sunrooms or enclosed patios. Every one of them gets the same Harris County permitting discipline and the same written change order process.
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 Alief
We don’t install mystery brands off a van. For hardscape tie-ins around ADU foundations and driveways, we run Techo-Bloc and Cambridge Pavers because their paver systems hold up to the clay movement and flood-drainage patterns we deal with in Alief. For concrete work, we use Quikrete and Oldcastle products that meet Harris County spec. When you see the material names in your contract, you can look them up yourself. We’d expect you to.
Common Home Additions & ADU Problems We See in Alief Homes
- Wrong jurisdiction filings. A contractor assumes the Houston Permitting Center portal and files there. Harris County Engineering never sees the application. The foundation inspection gets pushed past the storm window, and the homeowner eats the delay. We file Harris County first, every time.
- Undersized framing in 1970s ranch homes. Open up a back wall for a garage conversion and you’ll find 2×4 ceiling joists that can’t carry a second-story addition without an engineered LVL pack-out. If that’s not in the original quote, it becomes a surprise change order. We inspect and write it in before walls come down.
- Failed waterproofing at the slab-to-brick transition. This one hides until the first Brays Bayou flood after the ADU is dried in. Then it’s tear-out of new flooring and base cabinets. We catch it at rough-in and fix it before it becomes a warranty claim on our own work.
- Beaumont clay slab cracks. The expansive clay under Alief slabs moves with every wet-dry cycle. A hairline crack today is a structural question tomorrow. We evaluate slabs before quoting additions, and we epoxy-inject cracks that need it before framing starts.
Pricing for Home Additions & ADU in Alief, TX
Here’s what you should expect to pay in Alief as of 2026:
| Project Type | Typical Range in Alief |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction (detached) | $90,000-$220,000 |
| Garage Conversion ADU | $30,000-$80,000 |
What moves these numbers? For additions, it’s whether the existing framing can carry the load or needs an engineered beam package. For ADUs, it’s foundation work on Beaumont clay and flood-plain drainage requirements. Every quote we give includes a line-by-line scope, written allowances for the things we can’t see until walls are open, and a fixed price that doesn’t move unless you approve a written change order. Call (877) 610-1318 for a free estimate. You’ll see every number before you sign.
We Also Serve Cities Near Alief
Our crews work throughout southwest Harris County and the neighboring communities just beyond the Beltway. If you’re in Four Corners, Mission Bend, Stafford, or New Territory, you’ll get the same Harris County permitting discipline and the same written change order process we bring to every job in Home Additions & ADU in Alief. Scheduling is coordinated from our Houston office, but the crews on your job live and work in this area.
Serving Alief, TX - Our Local Coverage Area
We’re based in the Alief 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 Alief
You need a Harris County permit. Alief is unincorporated, which means Harris County Engineering runs the permitting, inspections, and code enforcement, not the Houston Permitting Center. Filing in the wrong jurisdiction costs you two weeks or more. We file Harris County first, and we walk the plans through their separate fee schedule and inspection workflow before we start. Call (877) 610-1318 and we’ll confirm your specific address’s jurisdiction on the first call.
Plan on new ground-fault and arc-fault circuits, smoke and CO detectors tied to the new space, egress window retrofits in any converted bedroom, and often a subpanel upgrade if the original electrical from 1975 is still in place. Those are not optional. Harris County will require them at rough-in inspection, and we’ll have them scoped as written allowances before a single wall is opened. Call (877) 610-1318 and we’ll give you the exact list for your home during the estimate.
We stop at rough-in, have Harris County inspect the exposed framing and any electrical we’ve touched, then write a change order for anything the inspection flags or that we find before closing walls. You see every number in writing, and you approve it, before we buy material or do the work. On a 1979 brick-veneer ranch near Brays Bayou, we found ungrounded 14-gauge wiring and slab hairline cracks during a garage conversion. We wrote a change order for a new subpanel, ground rods, and epoxy crack injection. The homeowner saw every number before we touched it. Call (877) 610-1318 for an estimate built on the same process.
Almost certainly yes. The 1970s stock here was framed with undersized 2×4 ceiling joists that can’t carry a second story without an engineer’s LVL pack-out or a flitch beam. That’s not a surprise when we quote it; it’s a line item in the original scope. If a contractor quotes a second-story addition in Alief at a fixed price without an engineered beam allowance, the surprise is coming. Call (877) 610-1318 and we’ll tell you what your existing framing will carry before you commit.
The sequence runs foundation, framing and electrical rough-in, mechanical and plumbing rough-in, insulation and drywall, then final. Each one is a Harris County inspection, and each one has a separate scheduling window. If you miss the foundation inspection because someone filed with Houston, the entire sequence shifts and you can end up framing in hurricane season. We schedule inspections in order, we show up for them, and we don’t close walls until the inspector signs. Call (877) 610-1318 and ask us to walk your project’s sequence before you sign anything.
Call Barrett & Sons Construction for Your Alief Home Addition or ADU
If you’re thinking about a garage conversion, a second-story addition, or a full detached ADU in Alief, start with a conversation that puts every number in front of you in writing. Tom Barrett’s name, address, and license number are published and verifiable. His sons answer the phone. The 90-Day Done Right Promise is written on every contract, and every price change comes as a written change order before a single nail moves. Call (877) 610-1318 to schedule your free estimate. We’ll walk your lot, check your slab, listen to what you want, and hand you a scope you can take to anyone. Then you decide.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Alief and southwest Harris County since 1998.