Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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After
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AfterFast, Reliable Home Additions & ADU Across Missouri City
A room addition or ADU in Missouri City typically runs $45,000 to $130,000, and the timeline depends on something most contractors never check: which county your address actually sits in. Missouri City straddles Harris and Fort Bend County, so a permit pulled from the wrong authority will stall your project before framing starts. We’ve built enough additions in Missouri City to check the county line before we check the tape measure. Call (877) 610-1318 and we’ll walk your property, verify the jurisdiction, and give you a written line-item estimate with no obligation.
Tom Barrett and his sons run our Home Additions & ADU crews, and they’re on-site in Missouri City most days. We’re not a franchise dispatching strangers. We’ve added second stories in Quail Valley, converted garages into rentable ADUs in New Territory, and navigated Sienna’s HOA design-review process more times than we can count. When you call, you get a live person. When we quote, you get a number that holds. When something changes, you get it in writing before a single nail moves.
Why Barrett & Sons Construction Is Missouri City’s Preferred Home Additions & ADU Company
We’ve been building home additions since 1998, and in Missouri City we’ve learned to respect the dual-county reality that catches out-of-area contractors off guard. A home on one side of Cartwright Road may fall under Harris County rules. The house across the street could be Fort Bend County’s jurisdiction, with different inspectors, different code cycles, and different elevation requirements. Pull the wrong permit and you lose weeks. We verify the county before we draw the plans.
Our Missouri City customers talk. A Quail Valley homeowner referred us to her sister in Sienna Plantation after we brought her 1978 ranch up to current code and added a 400-square-foot primary suite. A New Territory couple hired us to convert their garage into a two-bedroom ADU after their previous contractor walked off the job. We finished it, signed off with Fort Bend County, and handed them a written 90-Day Done Right Promise before we left. Tom Barrett publishes his name, his address, and his license number, and he says the same thing to every Missouri City customer: look it up before you sign anything.
We answer our own phone, 24 hours a day. We don’t route calls to an out-of-state call center. When a Missouri City homeowner calls about a roofline issue on a second-story addition, they talk to someone who knows what a Sienna HOA architectural submittal looks like. That matters here.
Key Takeaways
- Missouri City spans Harris and Fort Bend County. We verify which county governs your parcel before permits are pulled.
- Every price change is a written change order. No surprise invoices.
- Permits pulled and inspections signed on every eligible job. The permit inspector works for you, not for us, and we like it that way.
- 90-Day Done Right Promise written on every contract. One call brings Tom back.
- Free estimates. Call (877) 610-1318.
Our Home Additions & ADU Services in Missouri City
ADU Design & Permitting
An ADU in Missouri City starts with the question every contractor should ask but few do: is this parcel in Harris or Fort Bend County? We draw ADU plans that account for your county’s specific setback rules, flood-elevation requirements, and utility connection standards. From first sketch to signed permit, we handle the paperwork so you don’t have to chase inspectors. A detached ADU in Missouri City typically runs $90,000 to $220,000 depending on size, finishes, and site work.
Garage Conversion ADU
Garage conversions are the fastest path to a rentable unit or in-law suite in Missouri City, and they run $30,000 to $80,000 here. But before we touch a wall, we check the FEMA flood zone map. In 2017, Hurricane Harvey put whole Missouri City subdivisions underwater, and any substantial improvement now triggers flood-elevation scrutiny. If your slab sits in flood zone AE, Fort Bend County will want finished-floor elevation data before rough-in. We handle that. We also make sure the conversion doesn’t trigger a stop-work order from your HOA, which is a real risk in Sienna and New Territory.
New Detached ADU
A new detached ADU in Missouri City gives you rental income or a private space for aging parents without sharing walls. In Sienna, the HOA’s Residential Design Committee must approve exterior materials, roof pitch, and color palette before the permit application even reaches Fort Bend County. That dual approval adds 3 to 6 weeks to the front of the project, but skipping it will cost you more time in stop-work orders. We plan for that review from day one. Budget $90,000 to $220,000 for a new detached ADU, with site prep and utility runs as separate line items.
Junior ADU & Interior Conversion
A junior ADU converts existing interior space, like a bonus room or oversized garage bay, into a small self-contained unit with a kitchenette and bath. For older Missouri City homes in the 77489 zip code, this is often the most economical way to add a rental unit without the foundation work a detached ADU would demand. We’ve converted 1970s ranch layouts into bright, code-compliant one-bedroom units, pulling permits and passing inspections in both Harris and Fort Bend County. Expect $45,000 to $80,000 depending on plumbing runs and electrical upgrades.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
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 Missouri City
We install materials that have a paper trail, not mystery brands off a van. For Missouri City additions and ADUs, that means Techo-Bloc pavers on walkways and patio connections, Cambridge Pavers where a new driveway meets the street, and Quikrete products on stem walls and slab repairs. We keep local supply relationships so Missouri City customers aren’t waiting on a pallet from three states away. When your HOA has a color palette or material standard, we know which brands meet the spec and which will bounce back from the design committee.
Common Home Additions & ADU Problems We See in Missouri City Homes
- Wrong-county permits. A Missouri City home on the Harris County side needs a Harris permit. On the Fort Bend side, it’s Fort Bend. Pulling from the wrong authority voids the application and adds weeks. We check the county line before we draft anything.
- Sienna HOA stop-work orders. Framing a second story before the Residential Design Committee approves exterior color and roof pitch triggers a stop-work order that can idle a crew for a month. We submit the architectural package first, then pull the permit.
- Flood zone surprises mid-rough-in. A garage conversion that starts without checking FEMA flood maps can hit a wall when the county demands finished-floor elevation changes during framing. We run the flood zone check as step one on any Missouri City property near Oyster Creek or the Brazos River floodplain.
- Clay soil movement on older slabs. The same Beaumont clay that plagues greater Houston has spent decades moving foundations in Quail Valley and the 77489 area. A second-story addition on a moving slab needs a structural evaluation before we frame. We won’t add load to a foundation that hasn’t been checked.
Pricing for Home Additions & ADU in Missouri City, TX
Here’s what we see in the Missouri City market right now. A room addition runs $45,000 to $130,000, with the spread driven by foundation work, roof tie-ins, and HOA requirements. A detached ADU lands between $90,000 and $220,000. A garage conversion is $30,000 to $80,000. These are real numbers for Missouri City, not national averages. In Sienna, expect the HOA design-review process to add 3 to 6 weeks, not necessarily cost. In Quail Valley, older slab conditions may add a structural line-item. Every scope is in writing. Every allowance is in writing. Every change order is in writing before work happens.
| Project Type | Missouri City Price Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
Call (877) 610-1318 to schedule a free estimate. You’ll get a written line-item quote, not a number scribbled on a business card.
We Also Serve Cities Near Missouri City
Our crews work throughout Missouri City and the surrounding communities, including Stafford, Fresno, Sienna Plantation, and New Territory. If you’re just outside the Missouri City line and wondering whether we cover your street, call (877) 610-1318 and ask. We’ll tell you straight.
Serving Missouri City, TX - Our Local Coverage Area
We’re based in the Missouri City 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 Missouri City
No. Missouri City issues its own permits, but which county’s building codes apply depends on which side of the county line your parcel sits on. The city permit covers local zoning and building review. The county layer covers flood elevation, drainage, and sometimes septic or utility connections. We verify both before we file anything. Call (877) 610-1318 and we’ll pull your property’s jurisdiction in about five minutes.
Yes. In Sienna, the HOA’s Residential Design Committee must approve exterior materials, roof pitch, and color palette before Fort Bend County will process the permit. Plan for 3 to 6 weeks of review. We prepare the architectural package to Sienna’s standards the first time, because a rejection letter resets the clock.
Yes, with conditions. If your parcel sits in FEMA flood zone AE, Fort Bend County will require a flood-elevation certificate and may mandate finished-floor height changes before you frame. We run the flood zone check before we design, not after rough-in. Call (877) 610-1318 for a free evaluation of your specific lot.
A new detached ADU in Missouri City runs $90,000 to $220,000. The Sienna HOA approval process adds time, not necessarily cost, unless the design committee requires material changes. Budget $90,000 as a floor and expect site prep, utility runs, and finish selections to move the final number. A written line-item estimate before you sign is the only way to know your real number.
Usually, but not before a structural evaluation. The Beaumont clay under Quail Valley has spent four decades expanding and contracting, and adding a second story to a moving slab without checking it is a recipe for cracks and callbacks. We bring in a structural engineer to assess the slab and foundation before we design the second story. If the slab checks out, we frame. If it needs work, we tell you exactly what and what it costs.
In a Quail Valley ranch on the 77489 side, our crew tore out a sagging 1978 slab-on-grade addition and re-framed the load-bearing wall after the Fort Bend inspector required a foundation elevation certificate because the parcel sits in FEMA flood zone AE. We shifted the finished-floor height, re-pitched the roof to match the architectural standards the owners had seen on Sienna homes, and closed the job with a clean punch list and inspection sign-off before drywall.
An allowance that isn’t on paper is a surprise waiting for a date. We put everything on paper. Tom Barrett lives twenty minutes from most Missouri City job sites, and if something’s wrong, he wants to know about it. Call (877) 610-1318 and ask for a free estimate. We’ll walk your property, check your county, check your flood zone, and tell you what your addition or ADU will actually cost before you spend a dime.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Missouri City since 1998.