Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Fort Worth ADU cost →Building an ADU in Fort Worth costs between $130,000-$320,000 for new construction, with per-square-foot costs averaging $250-$400. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $30,000-$100,000, while prefab/modular ADUs fall in between at $150,000-$300,000.
A detached ADU in Fort Worth typically runs $130,000-$320,000 all-in for new construction ($250-$400 per sq ft). A garage conversion is the cheapest path at $30,000-$100,000, and a prefab ADU averages $150,000-$300,000. Add the city building permit and plan review ($300-$900 building permit for a 500-1,200 sq ft unit. FY2027 Table 1-C-3 (R use groups, fee ordinance on the Sept 15, 2026 Council budget agenda, effective Oct 1, 2026): an R-3 unit up to 500 sq ft pays $61.01 plus $0.45 per sq ft over 65; 65-700 sq ft $102 plus $0.74 per sq ft over 65; 700-1,400 sq ft $570 plus $0.53 per sq ft over 700. Worked: 500 sq ft about $257, 800 sq ft $623, 1,000 sq ft $729, 1,200 sq ft $835, plus a $33.08 application fee and $16.87 technology fee; no plan-review deposit for R-3 accessory structures. Until Sept 30, 2026 the FY2025-26 table (Ord. 27191-09-2024) applies: 500 sq ft $240.80, 800 sq ft $592.44, 1,000 sq ft $692.44, plus $31.50 and $16.87. A garage conversion is a residential remodel at $119 per trade ($595 for five trades, FY2027). Third-party plan review and inspection reduce the permit fee to 70%, 55% or 35%) and roughly $0 on the house's existing water meter; $5,828 impact fee plus $6,100-$11,700 in tap fees for a separate new water and sewer connection (Oct 1, 2026 rates). Fort Worth's water and wastewater impact fees are assessed per new or upsized meter, not per building (city Impact Fees FAQ): a 5/8 x 3/4-inch meter pays $5,504 combined from Oct 1, 2025 and $5,828 from Oct 1, 2026 (Council June 10, 2025), a 1-inch meter $14,570; a city-installed 1-inch water tap costs $2,900-$4,000 and a 4-inch sewer tap $3,200-$7,700 (§§ 35-57.4 and 35-57.5, FY2027). Transportation impact fees are collected at building permit on new development measured by land use (Ch. 30 Art. VIII); whether a non-rentable accessory unit is assessed is not published, so ask Development Services for an estimate in water/sewer connection charges. Fort Worth sets no square-footage cap: the unit is limited by your district's lot coverage, setbacks and the height of the house, and under Zoning Ordinance §9.101 it may not contain cooking equipment or be rented, so most homeowners build a guest or family suite at the lower end of these ranges. Texas has no statewide ADU subsidy or impact-fee waiver, so plan for the full permit and utility costs.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $300-$900 building permit for a 500-1,200 sq ft unit. FY2027 Table 1-C-3 (R use groups, fee ordinance on the Sept 15, 2026 Council budget agenda, effective Oct 1, 2026): an R-3 unit up to 500 sq ft pays $61.01 plus $0.45 per sq ft over 65; 65-700 sq ft $102 plus $0.74 per sq ft over 65; 700-1,400 sq ft $570 plus $0.53 per sq ft over 700. Worked: 500 sq ft about $257, 800 sq ft $623, 1,000 sq ft $729, 1,200 sq ft $835, plus a $33.08 application fee and $16.87 technology fee; no plan-review deposit for R-3 accessory structures. Until Sept 30, 2026 the FY2025-26 table (Ord. 27191-09-2024) applies: 500 sq ft $240.80, 800 sq ft $592.44, 1,000 sq ft $692.44, plus $31.50 and $16.87. A garage conversion is a residential remodel at $119 per trade ($595 for five trades, FY2027). Third-party plan review and inspection reduce the permit fee to 70%, 55% or 35% |
| Impact Fees | $0 on the house's existing water meter; $5,828 impact fee plus $6,100-$11,700 in tap fees for a separate new water and sewer connection (Oct 1, 2026 rates). Fort Worth's water and wastewater impact fees are assessed per new or upsized meter, not per building (city Impact Fees FAQ): a 5/8 x 3/4-inch meter pays $5,504 combined from Oct 1, 2025 and $5,828 from Oct 1, 2026 (Council June 10, 2025), a 1-inch meter $14,570; a city-installed 1-inch water tap costs $2,900-$4,000 and a 4-inch sewer tap $3,200-$7,700 (§§ 35-57.4 and 35-57.5, FY2027). Transportation impact fees are collected at building permit on new development measured by land use (Ch. 30 Art. VIII); whether a non-rentable accessory unit is assessed is not published, so ask Development Services for an estimate |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Fort Worth, where we have them — free, no obligation.
Get Fort Worth builder quotes →Permit fees in Fort Worth are $300-$900 building permit for a 500-1,200 sq ft unit. FY2027 Table 1-C-3 (R use groups, fee ordinance on the Sept 15, 2026 Council budget agenda, effective Oct 1, 2026): an R-3 unit up to 500 sq ft pays $61.01 plus $0.45 per sq ft over 65; 65-700 sq ft $102 plus $0.74 per sq ft over 65; 700-1,400 sq ft $570 plus $0.53 per sq ft over 700. Worked: 500 sq ft about $257, 800 sq ft $623, 1,000 sq ft $729, 1,200 sq ft $835, plus a $33.08 application fee and $16.87 technology fee; no plan-review deposit for R-3 accessory structures. Until Sept 30, 2026 the FY2025-26 table (Ord. 27191-09-2024) applies: 500 sq ft $240.80, 800 sq ft $592.44, 1,000 sq ft $692.44, plus $31.50 and $16.87. A garage conversion is a residential remodel at $119 per trade ($595 for five trades, FY2027). Third-party plan review and inspection reduce the permit fee to 70%, 55% or 35%. The review timeline is City-published first-review target for a residential building permit: 7 business days from a complete application (Review Timeframes page, 2026); urban forestry review 7 business days; a zoning variance about 1.5 months; a PD rezoning about 3 months from the monthly application deadline. The city publishes no end-to-end permit figure; total time depends on correction rounds, with plan check: Included in the building permit fee; first comments in 7 business days. Each revision round is billed per hour (FY2027: $66.15 first, $119 second, $237 third and fourth, $375 fifth and up). Expedited review costs a $500 application fee plus $1,125 per hour. Third-party plan review is allowed and cuts the permit fee to 70% (55% for third-party inspections, 35% for both). Impact fees are $0 on the house's existing water meter; $5,828 impact fee plus $6,100-$11,700 in tap fees for a separate new water and sewer connection (Oct 1, 2026 rates). Fort Worth's water and wastewater impact fees are assessed per new or upsized meter, not per building (city Impact Fees FAQ): a 5/8 x 3/4-inch meter pays $5,504 combined from Oct 1, 2025 and $5,828 from Oct 1, 2026 (Council June 10, 2025), a 1-inch meter $14,570; a city-installed 1-inch water tap costs $2,900-$4,000 and a 4-inch sewer tap $3,200-$7,700 (§§ 35-57.4 and 35-57.5, FY2027). Transportation impact fees are collected at building permit on new development measured by land use (Ch. 30 Art. VIII); whether a non-rentable accessory unit is assessed is not published, so ask Development Services for an estimate. Pre-approved plans: None. The city's Housing Affordability Strategy funds a neighborhood pattern book of pre-approved designs, including ADUs, through a $5 million HUD PRO Housing grant; the design RFP was expected in September 2026 (Community Development Committee briefing, Sept 15, 2026). Strategy 4, 'Encourage Accessory Dwelling Units', is listed but had no update at that briefing.
| 1-Bedroom Rent | $1,250-$1,500/month |
| 2-Bedroom Rent | $1,550-$1,750/month |
| Annual Rental Income (est.) | $16,500/year |
| Payback Period (est.) | 13.6 years |
| Short-Term Rental | No. |
| Overall ROI Estimate | None on a one-family lot: the unit cannot be leased. A second detached unit on a 'B' lot renting at $1,250-$1,750/mo on a $130,000-$320,000 build is a 5-12% gross yield before taxes, vacancy and financing |
A typical ADU in Fort Worth generates approximately $16,500 per year in rental income based on average 1-bedroom rents. At an average construction cost of $225,000, the estimated payback period is 13.6 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Fort Worth and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Fort Worth: $30,000-$100,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $150,000-$300,000.
3. Pre-approved plans — available in Fort Worth, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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