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 Houston
Home additions and ADU construction in Houston typically run between $45,000 and $130,000, with detached ADU builds starting around $90,000. The real question most Houston homeowners should ask isn’t about price. It’s whether the quote includes the wind-load straps, flood elevation checks, and deed-restriction searches this city actually requires before a foundation gets poured. Skip those steps and you could own a slab that’s legally or structurally unbuildable.
Barrett & Sons Construction has been owner-operated since 1998, and Tom Barrett’s name is on every truck that rolls into Houston neighborhoods like Montrose, the Heights, and Braeswood Place. We answer our own phone at (877) 610-1318, and we’ll give you a straight answer about what your lot can actually support before we ever talk numbers. That’s how we’ve kept Houston customers calling us back for 29 years.
Why Barrett & Sons Construction Is Houston’s Preferred Home Additions & ADU Company
We’re not a franchise dispatching strangers to Houston. Tom Barrett and his sons run the crews themselves, and they’re on-site most days. If you live in the Heights or Bellaire, there’s a good chance you’ll see one of them at the hardware store on Saturday. That’s the point. When something goes wrong months after a job wraps, you don’t call an 800 number and hope for a callback. You call Tom, and Tom answers.
Every contract we write includes our 90-Day Done Right Promise in plain language: if it’s not done right, one call brings Tom back to make it right. Every price change arrives as a written change order before work happens. And every eligible job in Houston gets permits pulled and inspections signed, because the permit inspector works for you, not for us. That’s why we like him. We want the city checking our framing, our foundation, and our flashings. It keeps everyone honest.
Our clients in Houston’s 77006, 77007, and 77008 ZIPs know we understand something most contractors don’t: this city has no zoning ordinance. The permit office will happily stamp a build that a deed restriction later kills. We run the title search first. That’s the kind of local knowledge that saves Houston homeowners from six-figure mistakes.
Our Home Additions & ADU Services in Houston
ADU Design & Permitting
Houston is the largest U.S. city with no zoning code, which means an ADU that gets a city permit can still be blocked by a private deed restriction nobody at the permit counter checks. We run title searches on every lot before we draw plans. In neighborhoods like Montrose (77006) and the Heights (77007-77008), that single step has saved our clients from pouring foundations on legally unbuildable lots. The design work accounts for your finished floor elevation, your flood zone designation, and your wind-load requirements from day one, not as an afterthought two weeks into framing.
Garage Conversion ADU
Converting an attached or detached garage into a livable ADU in Houston runs $30,000 to $80,000 depending on whether you’re adding a bathroom, a kitchenette, or both. The catch in this city is foundation work. Many older Houston garages sit on slabs that were never designed for living-space loads, and if your garage predates the post-Harvey FIRM remapping, the finished floor elevation may not meet current floodplain standards. We pull the geotechnical report before we touch concrete. That report tells us whether the Beaumont Clay under your garage can handle the load, or whether we need to underpin first.
New Detached ADU
A new detached ADU in Houston starts around $90,000 and can reach $220,000 for a fully finished two-bedroom unit with a full kitchen. The site prep alone is where Houston gets expensive. This city sits largely at or below 50 feet elevation on the Gulf Coastal Plain, and Hurricane Harvey’s FEMA remapping pushed large portions of the inner loop into revised flood zones. That means your ADU’s slab height is dictated by your flood zone, not by what looks good. We set the finished floor elevation from the FIRM map before we order the first load of concrete. Two wet seasons on Beaumont Clay will expose a slab that was set too low, and that’s a tear-out nobody wants to pay for twice.
Junior ADU & Interior Conversion
Junior ADUs are the quiet workhorse of Houston’s inner loop. A converted garage apartment, a finished attic, or a carved-out portion of an existing bungalow can give an aging parent or adult child their own space without triggering the same floodplain scrutiny a full detached unit faces, provided the conversion doesn’t change the building’s footprint. Second-story additions over original 1920s pier-and-beam foundations are common in Montrose and the Heights, and they demand real structural engineering. We shored up a Montrose bungalow last year where termite damage had turned a load-bearing wall into dust. That discovery triggered a change order, an engineered beam, and a re-laid subfloor to meet current wind-load shear standards before the city inspector would sign off. The homeowners came out ahead: their updated elevation certificate cut their flood premium by 18%.
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 Houston
We install materials you can look up, not mystery brands off a van. On Houston additions and ADUs, that means products like Cambridge Pavers and Techo-Bloc for any hardscape that ties the structure to the lot, and Quikrete and Oldcastle for foundations and site concrete. These are names any Houston building supply counter stocks, which matters when you need a repair five years from now and the original material is still available. We don’t substitute off-brand equivalents to pad a margin. What we quote is what goes on your job, in writing.
Common Home Additions & ADU Problems We See in Houston Homes
- Deed restriction injunctions stopping work mid-build. A contractor pulls a permit for an ADU in the Heights, pours a slab, and only then discovers the lot’s deed restriction prohibits detached structures. The city cannot lift the injunction. The project stalls indefinitely. We never pour concrete before the title search comes back clean.
- Slabs set too low for the post-Harvey flood map. Adding a room without verifying the finished floor elevation against the current FIRM map means a floodplain administrator can red-tag the work and force a tear-out. That’s a five-figure mistake that only gets caught if somebody checks the elevation before the pour.
- Second-story additions shearing away from original pier-and-beam framing. Houston’s Beaumont Clay expands and contracts with the seasons. Without a geotechnical report and proper shear strapping, a new upper floor moves differently than the 1920s framing below it. Within two wet seasons the joint fails, and the structural warranty is void. Wind-load rated straps and ties are not optional here.
- Foundation-only permits that ignore floodplain requirements. Converting a Heights garage to an ADU with just a foundation permit skips the floodplain review entirely. The permit looks complete on paper and is worthless the moment the floodplain administrator reviews the finished project. Houston requires the elevation certificate as part of the permit file on any livable-space conversion.
Pricing for Home Additions & ADU in Houston, TX
Here’s what we’re actually seeing on Houston jobs right now, and what that money covers. These are line-item ranges, not phone quotes. The number we give you comes from a written scope, not a guess.
| Service | Houston Price Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
What moves the number in Houston specifically? Three things. First, your flood zone. A post-Harvey FIRM designation that pushes your finished floor up two feet adds real foundation cost. Second, your soil. Beaumont Clay in the inner loop often requires deeper footings or underpin work you wouldn’t need in, say, Bellaire’s sandier lots. Third, your lot’s deed restrictions. A title search that reveals you can only attach an ADU to the main house changes the entire design and the structural engineering budget. A quote that ignores these three things is not a real quote. Call (877) 610-1318 for a written estimate that accounts for all of them. Estimates are free.
We Also Serve Cities Near Houston
Our crews work across Houston’s inner loop and the surrounding communities every week. If you’re in Bellaire, we understand the city’s stricter residential code enforcement and plan review timeline. In West University Place, we navigate the local deed restrictions and architectural review boards. Galena Park and Jacinto City homeowners call us for additions and ADUs that meet Harris County floodplain standards. Wherever you are, our Houston roots mean we’re close by and familiar with your specific jurisdiction. Learn more about our full Home Additions & ADU capabilities and how we approach each project.
Serving Houston, TX - Our Local Coverage Area
We’re based in the Houston 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 Houston
No. Houston has no zoning ordinance, so there is no zoning variance to request. What Houston has instead is a patchwork of private deed restrictions that city permits do not check. In neighborhoods like the Heights (77007-77008) and Montrose (77006), the only legal restriction on an ADU may be a private covenant on your specific lot’s title. You need a title search before you spend a dollar on design, because a deed restriction violation can trigger a neighbor-initiated injunction that city hall cannot lift. Call (877) 610-1318 and we’ll run that title search before we draw a single line.
Houston additions and ADUs must meet the wind-load standards in the current International Residential Code with Texas amendments, which for Harris County generally means design wind speeds in the 130 to 140 mph range depending on your exact exposure category and lot location, and that translates to specific hurricane tie and shear wall requirements at every roof-to-wall and wall-to-floor connection. A compliant quote includes the full shear panel schedule, the strap and tie specifications, and the engineering calcs sealed by a Texas-licensed engineer. A cheap quote leaves those out and hopes the inspector doesn’t look too hard. Ours are in the contract, in writing, before framing starts.
A post-Harvey finished-floor elevation certificate that shows your addition or ADU sits above the base flood elevation for your FIRM zone can directly reduce your flood insurance premium, and in the inner loop, where FEMA remapping pushed thousands of lots into higher-risk zones after 2017, that certificate is often the difference between a four-figure and a five-figure annual premium. The elevation has to be documented by a licensed surveyor and filed with the floodplain administrator for the credit to apply. We coordinate that survey as part of the permit package. Not every contractor does, and their clients pay for the omission every year.
A foundation-only permit covers the structural slab work but skips the floodplain review and the change-of-use review that a garage-to-ADU conversion legally requires in Harris County. The moment the floodplain administrator or a neighboring title holder reviews the project, that foundation-only permit is exposed as incomplete, and the city can stop work on a technically permitted slab. In the Heights, where deed restrictions often prohibit detached living structures outright, converting a garage also requires a title search to see whether your specific lot even allows a second dwelling unit. We pull both the building permit and the floodplain development permit, and we run the title search first. Call (877) 610-1318 before you start, and we’ll walk you through exactly what your lot allows.
In Montrose’s 77006 ZIP, a second-story addition on an original 1920s pier-and-beam home triggers this sequence: a zoning-equivalent review (which in Houston means a deed-restriction check, not a zoning variance), a geotechnical report on the Beaumont Clay under the existing piers, a structural review by a Texas-licensed engineer, a foundation inspection on the shoring plan, a shear wall and wind-load straps inspection at framing, and finally a finished-floor elevation certificate filed with the floodplain administrator if your lot falls in a revised post-Harvey flood zone. Skip any one of these and the inspection chain stops. We’ve done this exact sequence on Montrose bungalows, and we know what the city’s plan reviewers expect to see in each folder. Call (877) 610-1318 and we’ll give you a free estimate that includes every inspection step in writing.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Houston since 1998.