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ADU construction in Houston typically costs between $90,000 and $220,000 for a complete, turnkey accessory dwelling unit in 2026. A standard one-bedroom detached ADU of roughly 600 to 800 square feet on a Houston lot generally lands between $130,000 and $170,000, while garage conversions run $30,000 to $80,000 as a lower-cost alternative. If you’re comparing bids right now, you’ll find most Houston ADU builders fall somewhere inside that $90,000 to $220,000 band depending on whether you’re converting existing square footage or pouring a new slab.
Before we get into the line items, you should know how Bradford Remodeling Co Houston approaches an ADU job. Curtis Lane, who runs our Houston operation, puts every price in writing before a single tool comes out. No numbers that move at the door. That’s The Garrison Standard, and it applies to every ADU we build, whether it’s a detached backyard unit in Bellaire, a garage apartment in the Heights, or a rear-lot cottage in Pasadena.
Key Takeaways:
- Detached ADU construction in Houston: $90,000 to $220,000 all-in
- Garage conversion ADU: $30,000 to $80,000
- Per-square-foot cost for new ADU construction: roughly $180 to $320, depending on finishes and site conditions
- Houston’s permit fees, foundation requirements, and flood-plain rules can swing the final number by $10,000 or more
- Bradford’s written price and 365-Day Done Right Promise apply to every ADU project, no exceptions
ADU Construction Cost Breakdown (2026)
Here’s where the money goes on a typical detached ADU in Houston. These are real numbers from our bids and completions across Harris County, not national averages. Use them to check any estimate you receive.
| Cost Category | Typical Range (Houston, 2026) | Notes |
|---|---|---|
| Site prep & foundation | $9,000 – $28,000 | Includes tree removal, grading, slab or pier-and-beam. Houston’s clay soil means piers or post-tension slabs on many lots. |
| Framing & shell | $22,000 – $55,000 | Walls, roof structure, sheathing, house wrap. Houston wind-load requirements affect Simpson tie-downs and strapping. |
| Roofing | $5,000 – $14,000 | Asphalt shingles are standard; metal adds $8,000 to $18,000. Houston’s hurricane-wind codes drive fastener schedules. |
| Rough-in: electrical, plumbing, HVAC | $14,000 – $32,000 | Includes tie-in to main house panel or new subpanel, sewer connection, mini-split or ducted HVAC. |
| Insulation & drywall | $4,000 – $9,000 | Minimum R-13 walls and R-30 attic per current IECC. Spray foam adds $3,000 to $6,000. |
| Interior finishes | $16,000 – $40,000 | Flooring, trim, doors, paint, tile work. This is where cabinet and countertop choices move the needle. |
| Kitchenette & bath fixtures | $10,000 – $28,000 | Compact kitchen with KraftMaid or Wellborn cabinetry, Kohler or Moen fixtures, Cambria or Caesarstone surface. |
| Permits, inspections & fees | $3,000 – $9,000 | City of Houston permit fees, plan review, inspection fees. Varies by final valuation. |
| Utility connections & site utilities | $4,000 – $18,000 | Water, sewer, gas line, electric service. Distance from the main dwelling drives this number hard. |
| Site work, driveway & landscaping | $3,000 – $12,000 | Walk-up path, parking pad, drainage, sod or hardscape repair. |
Add those up and you’re looking at roughly $90,000 on the lean end and $220,000 on a well-appointed detached unit. That range is consistent with what we’re seeing across Houston neighborhoods, from Meyerland to Spring Branch to the East End. The difference between $90,000 and $220,000 is not contractor markup – it’s square footage, foundation type, finish level, and utility distance.
If any Houston contractor hands you a per-square-foot number without seeing your lot, be careful. Houston is not one market. A flat lot in Katy with easy sewer access builds differently than a rear-lot pad in Garden Oaks where the electrical service has to run 120 feet from the alley. Anyone who quotes before looking is guessing.
What Affects ADU Construction Pricing in Houston
Six things move the number on a Houston ADU more than anything else. Here they are, in plain terms.
- Foundation type. Houston’s gumbo clay soil expands and contracts through our dry-wet cycles. Post-tension slabs and pier-and-beam both work, but they cost different amounts depending on soil tests, lot slope, and tree coverage. A tree-heavy lot in Timbergrove may need root-barrier work or pier adjustments that add $4,000 to $10,000.
- Flood plain status. Huge one in Houston. If your lot falls inside a FEMA-designated flood zone, finished floor elevation requirements kick in. Raising a structure 12 to 24 inches can add $8,000 to $22,000. Harris County flood regulations also affect drainage plans and slab height. We check the flood map before we quote, every time.
- Utility distance and connections. The shorter the run from the main house to the ADU, the lower the cost. A 20-foot electrical and sewer tie-in is a different job than trenching 90 feet across a backyard in Oak Forest. Water-line size, sewer cleanout access, and gas-line routing each carry their own cost.
- Finish level. Builder-grade cabinets, laminate counters, and stock plumbing fixtures keep you near the bottom of the range. KraftMaid cabinetry, Cambria quartz, and Kohler fixtures put you mid-to-high. We install name-brand materials with documented specs so you know exactly what you’re getting on paper.
- Size and roofline. Complexity drives cost faster than square footage. A simple 600-square-foot gable box builds cheap per square foot. A 900-square-foot unit with two dormers, a 12-foot vault, and a rear porch builds at a different rate. Every extra angle on the roof is money.
- Permit and plan timeline. City of Houston plan review for an ADU can take weeks depending on current backlog. We handle the full permit package, and our written price includes all permit and inspection fees up front. We don’t come back mid-project asking for more.
Each of those factors affects a Houston ADU bid differently than the same project in Dallas or San Antonio. This market has its own soil, its own flood rules, and its own utility trenching conditions. That’s why you want a contractor who builds here, not a franchise that drops a national template on your lot.
How to Save on ADU Construction
You can lower the number without cutting corners. Here’s what actually works in Houston.
- Convert instead of build new. A garage conversion runs $30,000 to $80,000, often less than half the cost of a detached build. The slab, framing, and roof already exist. Houston garages are typically 400 to 480 square feet – enough for a studio or one-bedroom ADU. The trade-off is parking, but many Houston homeowners take that swap without looking back.
- Keep the roofline simple. A single gable. One plane, no hips, no dormers. Every roof angle adds framing labor, sheathing cuts, flashing, and inspection time. Save $5,000 to $12,000 by saying no to decorative roof geometry.
- Choose builder-grade finishes now, upgrade later. Flooring, light fixtures, and cabinet hardware are easy to swap. Put your money into the shell, the electrical panel, and the foundation – those are expensive to redo. A Houston ADU with a solid envelope and basic finishes still rents well and builds equity.
- Place the ADU close to the main house. Shorter utility runs mean smaller trenching bills. A 30-foot difference can mean $3,000 to $8,000 saved. In a lot-line city like Houston, the ADU often sits within 15 feet of the main structure anyway – use that.
- Get a written price before you commit. The biggest cost overrun is a contractor who doesn’t honor the bid. Bradford Remodeling Co Houston gives every homeowner a written price before work begins, and that price does not move. If the scope doesn’t change, the number doesn’t change. Call (940) 289-7658 for a free estimate and we’ll walk your lot and give you the real number.
One more thing on saving money – don’t save it on the wrong line items. The City of Houston permits and inspections are not optional. Skipping them can void your insurance, block a future sale, and trigger code-enforcement fines. Bradford does not build unpermitted work. The Garrison Code – the conduct standard behind our operation – requires permits on every job, every time. A contractor offering a “no-permit discount” is not saving you money. He’s transferring the risk to you.
ADU Construction Price Ranges by Type
| ADU Type | Houston Price Range (2026) | What You Get |
|---|---|---|
| Garage conversion (existing) | $30,000 – $80,000 | Finished studio or one-bedroom in existing garage shell. Includes insulation, drywall, bath, kitchenette, utility tie-ins. |
| Attached addition ADU | $70,000 – $160,000 | Ground-floor or second-story addition with separate entrance. Shares one or more walls with the main house. |
| Detached studio (400 – 600 sq ft) | $90,000 – $150,000 | New build on slab or piers. One room plus bath and kitchenette. No separate bedroom wall. |
| Detached one-bedroom (600 – 800 sq ft) | $130,000 – $190,000 | Separate bedroom, full bath, full kitchen, stacked or side-by-side laundry. |
| Detached two-bedroom (800 – 1,000 sq ft) | $170,000 – $220,000+ | Two bedrooms, full bath or 1.5 bath, full kitchen, separate utility room. Upper end includes higher-grade finishes. |
Those are Houston-specific numbers. They reflect our local labor rates, Houston’s current material costs, and the permit fees in this specific market. We update them as conditions shift, not once every few years. As of 2026, those bands hold true.
How Bradford Remodeling Co Houston Builds an ADU
You can read our ADU Construction in Houston page for the full project flow, but here’s the short version of how it works with us. You call (940) 289-7658. A live person answers – not a voicemail, not a callback queue, 24 hours a day. We schedule a lot walk. Curtis Lane or one of our background-checked, uniformed project leads comes out, walks the site, checks the flood map, checks set-back requirements, checks utility tie-in points. Then you get a written price with the full scope in writing.
That written price covers materials, labor, permits, inspections, and every line item on the bid. If something isn’t listed, it isn’t charged. There are no “we didn’t know about that” invoices mid-project. That’s The Garrison Standard. It’s been the operating framework for the Garrison Partners family since 2004, and Bradford Remodeling Co Houston is independently owned and operated under that same standard.
During the build, your lead walks you through the rough-in stage – that’s the point after framing when electrical, plumbing, and HVAC lines go in before drywall covers them. In Houston, this is also when the first major city inspections happen. We schedule those, we’re on site for them, and we don’t cover a wall until the inspector signs off.
At close, you get a signed written guarantee in your hand. Every ADU we complete carries the 365-Day Done Right Promise. If anything on that project fails inside one full year, we come back and correct it. No charge. No argument. That’s the promise in writing, and it’s not conditioned on fine print.
That’s what “squared away” looks like at job close: clean site, documented scope, every permit closed and signed, and the written guarantee in your hand. That’s the standard we’ve operated under for over 20 years, and it doesn’t change because the project is big or small.
We build with name-brand materials you can verify: KraftMaid and Wellborn cabinetry, Cambria and Caesarstone surfaces, Kohler and Moen fixtures, GAF shingles, James Hardie siding, Therma-Tru exterior doors. Every material has a manufacturer spec and a manufacturer warranty that backs our own guarantee. No mystery-box materials, no “contractor’s choice” line items you can’t trace.
Houston ADU Permits and Code Requirements
Houston has its own ADU rules, and they affect cost. The City of Houston adopted ordinance language for accessory dwelling units that limits size, height, and placement. A typical ADU here is capped at either 800 square feet or 10% of the lot area, whichever allows more, and cannot exceed one story in most residential districts. Set-backs matter: 3 to 5 feet from side and rear property lines is common, but corner lots and flag lots add conditions.
Harris County flood-control rules apply across the city and unincorporated areas. If your property is in a designated floodway or the 100-year floodplain, finished floor may need to sit above the base flood elevation. That’s not a developer suggestion – it’s a permitting requirement. Elevation surveyors cost $800 to $2,500 on their own, and complying with the elevation requirement drives slab and fill costs up on the foundation line.
Also specific to Houston: our sewer infrastructure. Many pre-1980 neighborhoods still run on older wastewater capacity. Depending on location, a new ADU may require a separate sewer tap or a capacity check. That’s a fee, and sometimes a trench, and the number depends on your exact address and the City’s current tap fees. We handle that check during estimating so it’s in your written price, not a surprise later.
Electrical in Houston runs under the current NEC with local amendments. A detached ADU typically needs its own subpanel, and in some cases its own meter. If your main panel is at capacity – common on 1960s and 1970s Houston homes – you’ll need a panel upgrade, which adds $3,000 to $6,000. We identify that on the lot walk, not after the drywall goes up.
All of this is why Bradford quotes Houston ADUs in person and in writing. The rules change by neighborhood, by flood zone, by house age, by sewer district. A Houston-specific estimate is the only honest estimate.
FAQs – ADU Construction Cost
How much does a 600 sq ft ADU cost in Houston?
A 600-square-foot detached ADU in Houston runs $110,000 to $160,000 for a standard finish package. At the low end you’re getting a studio layout with a kitchenette and full bath. At the high end you’re getting a one-bedroom with full kitchen, upgraded flooring, and name-brand fixtures. Call (940) 289-7658 for a specific number on your lot – estimates are free and the price goes in writing before you commit.
Is it cheaper to build an ADU or convert a garage in Houston?
Garage conversion is cheaper, full stop. A Houston garage conversion runs $30,000 to $80,000, while a detached new-build ADU runs $90,000 to $220,000. The gap exists because a garage already has a slab, walls, and a roof. You’re paying for interior finish, utility tie-ins, and insulation rather than starting from dirt. The trade-off is losing covered parking – many Houston homeowners decide a covered carport or open driveway is worth the $60,000 to $100,000 savings.
How long does ADU construction take in Houston?
A garage conversion ADU typically takes 10 to 16 weeks once permits clear. A detached new-build ADU runs 4 to 8 months from groundbreaking to final inspection. Permit review time at the City of Houston adds 3 to 8 weeks on top of construction time, depending on current backlog and whether corrections are required. Bradford handles the full permit package so you’re not chasing reviews yourself.
What’s the cheapest way to build an ADU in Houston?
A basic garage conversion is the cheapest path at $30,000 to $60,000 for a code-compliant studio on the low finish end. After that, a small detached studio with simple gable roof and builder-grade finishes starts around $90,000. The best way to hold the number down is to keep the roofline simple, place the unit close to existing utilities, and choose basic finishes now while routing money into the shell and foundation. Bradford gives you a written price up front so the number you approve is the number you pay.
Do ADUs add value to a Houston home?
Yes, but the return depends on the build. A properly permitted detached ADU in Houston typically appraises between $90,000 and $220,000 on cost, and can return 60% to 80% of construction cost in immediate resale value, with the rest recovered through rental income or multi-generational housing use. Unpermitted work returns far less and can complicate a sale. Bradford builds every ADU fully permitted and documented, with the written guarantee and closed permits in hand at completion.
Can you build an ADU in a Houston flood zone?
Often yes, but it costs more. A flood-zone ADU in Houston requires finished floor elevation above the base flood elevation, which typically adds $8,000 to $22,000 depending on how much fill or pier height is needed. Harris County also requires drainage analysis for many ADU permits. Bradford checks the flood map before quoting, and any flood-related costs are in your written price – not discovered mid-build.
Home Improvement Cost Guides for Houston
While you’re planning your ADU, these Houston cost guides cover adjacent projects that often go along with it – or help you compare where your money goes.
- How Much Does a Kitchen Remodel Cost in Houston? – $14,000 to $45,000
- How Much Does a Bathroom Remodel Cost in Houston? – $9,000 to $28,000
- How Much Does a Home Addition Cost in Houston? – $45,000 to $130,000
- How Much Does a Garage Conversion Cost in Houston? – $30,000 to $80,000
- How Much Does a Roof Replacement Cost in Houston? – $8,000 to $20,000
- How Much Do Impact Windows Cost in Houston? – $8,000 to $25,000
If you’re weighing an ADU against a full home remodel, the cheaper path is often the ADU when you factor in rental income and avoiding the disruption of living through a whole-house renovation. But every lot is different. The only way to know is to walk it with someone who builds in Houston every week.
Get a Written ADU Price in Houston
Here’s the direct offer. Call (940) 289-7658 and ask for a free ADU estimate. A live person answers, 24 hours a day, 7 days a week. We’ll schedule a lot walk with Curtis Lane or one of our background-checked project leads. We’ll check your flood zone, your utility tie-in points, your permit path, and your set-backs. Then we’ll hand you a written price with the full scope documented. That price does not move unless the scope changes.
Every ADU we complete carries the 365-Day Done Right Promise in writing. If the work doesn’t hold up inside one year, we come back and fix it at no charge. That promise applies to the whole project – framing, roof, electrical, plumbing, drywall, finishes, everything. That’s The Garrison Standard, and we’ve been held to it since 2004.
Pricing reflects the Houston market as of 2026. Bradford Remodeling Co Houston offers free estimates – call (940) 289-7658.
Written by Curtis Lane, Owner at Bradford Remodeling Co Houston, serving Houston since 2004.
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