Everything homeowners ask about building an ADU in Houston — answered with 2026 data.
Yes, ADUs are allowed in Houston has no zoning. Under Code of Ordinances § 42-1, a lot with one house and a detached second dwelling unit of not more than 1,500 sq ft is 'single-family residential' (Livable Places amendments, Ord. 2023-801, eff. Nov 27, 2023), so a second unit is allowed on any single-family lot citywide unless recorded deed restrictions, the plat, or a special minimum lot size/building line designation for the block prohibit it. Where deed restrictions are stricter they control (§ 42-150(b)). in Houston, TX. The maximum size for a detached ADU is 1,500 sq ft. § 42-1 defines single-family residential to include 'a detached second dwelling unit of not more than 1500 square feet'; the cap was increased by the Livable Places amendments (Ord. 2023-801, eff. Nov 27, 2023). The code does not say how the area is measured; deed restrictions may set a lower cap or bar a second unit entirely. Attached ADUs can be up to No Chapter 42 cap. § 42-1 counts one building containing up to two units on a lot as single-family residential, so an attached second unit. Houston has an ADU-friendliness score of 7/10. Check our full Houston ADU rules page for complete zoning details.
ADU construction in Houston typically costs $140,000-$260,000. The cost per square foot averages $225-$350. Garage conversions are more affordable at $60,000-$110,000, while prefab ADUs cost $150,000-$300,000. Permit fees add Set by the City Fee Schedule (CPI increase of 1.391% on Jan 1, 2026): minimum building permit $91.06, minimum plumbing permit $97.56, administrative fee $33.56; the full residential fee formula was not readable this pass, so price your project with HPC's Fee Calculator. to your budget. See our detailed Houston ADU cost guide.
Detached ADUs in Houston can be up to 1,500 sq ft. § 42-1 defines single-family residential to include 'a detached second dwelling unit of not more than 1500 square feet'; the cap was increased by the Livable Places amendments. Attached ADUs are limited to No Chapter 42 cap. § 42-1 counts one building containing up to two units on a lot as single-family residential, so an attached second unit. Junior ADUs (JADUs) have a cap of No JADU category in Houston's code. A unit carved out inside the house is simply the second of the 'not more than two' units one building may hold (§ 42-1); no minimum or maximum size is set for it, and no owner-occupancy or covenant applies. Maximum height is No citywide height limit for single-family lots in Chapter 42 (the 30 ft cap in § 42-194 applies only to courtyard-style developments). Height is limited by deed restrictions, any platted restriction, and the Building Code; confirm with the Houston Permitting Center. You are allowed up to One detached second dwelling unit on a qualifying lot.
Rear setback: Chapter 42 sets no interior rear building line for a single-family lot; it sets 10 ft along a rear lot line that abuts a collector or local street (§ 42-156) and 3 ft along a shared driveway 18 ft or wider (§ 42-159). Interior rear lines are governed by deed restrictions, the plat and the Building Code's fire-separation rules — confirm with the Houston Permitting Center. Side setback: Chapter 42 sets no interior side building line for a single-family lot; 10 ft applies only along a side lot line that abuts a collector or local street (§ 42-156). Interior side lines come from deed restrictions, the plat and the Building Code's fire-separation distance to the property line — confirm with the Houston Permitting Center. Front setback: Platted front building line: 25 ft on a collector street and 20 ft on a local street (10 ft with a typical-lot-layout plat note), and 20 ft for a street-facing garage (§ 42-156); 10 ft under the § 42-157(b) performance standard, 5 ft or 0 ft where §§ 42-157(c)-(d) are met. A larger deed-restriction or special minimum building line controls (§ 42-150(b)-(c)); a second unit must sit behind the platted line. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
§ 42-186(b) and § 26-492: if the main house meets its own requirement (2 spaces, or 1 space if the house is 1,500 sq ft or less), a second unit of 1,000 gross sq ft or less needs no added space and a unit of 1,001-1,500 sq ft needs 1 added space. If the main house is short of spaces, the second unit needs 1 space. Lots under 33 ft of frontage get one 12-ft driveway per frontage and no extra driveway for the second unit (Livable Places User Guide, §§ 42-186, 42-188). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required. Chapter 42 contains no owner-occupancy, rental or deed-covenant condition for a second dwelling unit; either unit may be rented long-term. Recorded deed restrictions may impose their own limits. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Houston is typically Not published. The city posts no residential plan-review target; ask the Houston Permitting Center (832-394-9000) for current cycle times. Plan check: Not published; Houston Public Works reviews residential plans through ProjectDox and ILMS, with resubmittal cycles as needed. Pre-approved plans availability: ADU|HOU program: one free permit-ready plan set (the 'Double-House' design-competition winner, with preliminary Houston Public Works approval), a design book of 26 schematic designs, and three workshop videos. The program's web home (letstalkhouston.org/adu) no longer serves city content as of Sept 2026 — request the files from Planning & Development (832-393-6624).
Average ADU rental income in Houston: 1-bedroom units rent for $1,250-$1,900/month, 2-bedroom units for $1,500-$2,250/month. Short-term rentals: Yes, with a city certificate of registration per unit rented under 30 days (Ch. 28 Art. XXIII, Ord. 2025-322, eff. Jan 1, 2026): fee per City Fee Schedule, hotel tax, one-night minimum. Deed restrictions may bar STRs. Expected ROI: 6-12% gross rent yield (annual rent divided by build cost, before expenses).
The minimum lot size for an ADU in Houston is No ADU-specific minimum. A single-family lot with sewer service is 3,500 sq ft minimum inside the city (5,000 sq ft in the ETJ), reducible to 1,400 sq ft under the §§ 42-181 to 42-184 performance standards; a special minimum lot size area (§§ 42-197 to 42-208) controls where designated. The second unit must fit within the lot's building lines and parking. This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Houston, a garage conversion typically costs $60,000-$110,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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