How Much Does an ADU Cost in Arlington? Full 2026 Breakdown

Building an ADU in Arlington runs $60,000 to $330,000 depending on size and type. A 400-square-foot studio costs $60,000 to $110,000, while a 600-square-foot one-bedroom ranges from $90,000 to $165,000. A spacious 900-square-foot two-bedroom ADU runs $135,000 to $247,500, with garage conversions hitting the lower end and new detached units reaching the upper range.

Hard construction costs make up 70-80% of your total budget at $150-$275 per square foot. Soft costs add another $15,000 to $35,000, covering permits ($3,000-$8,000), design fees ($8,000-$15,000), and professional services ($4,000-$12,000). These numbers reflect Arlington's competitive construction market and straightforward permitting process compared to neighboring Dallas.

Texas gives cities complete control over ADU regulations since there's no statewide legislation. Arlington keeps things simple with three main residential zones. R-10 zones allow 40% lot coverage, R-5 zones permit 50%, and R-7 zones cap at 45%. Your lot coverage determines maximum ADU size more than zoning restrictions.

Garage conversions offer the best value at $150-$200 per square foot because you're working with existing structure, foundation, and roof. Converting a two-car garage creates a 400-500 square foot unit for $60,000-$100,000. Detached new construction costs $200-$275 per square foot but gives you complete design freedom and doesn't sacrifice parking.

Arlington's 4-8 month timeline includes 2-3 months for permits and design, then 2-5 months for construction depending on size and complexity. Fast-track your project by using pre-approved plans available from local architects for $2,000-$5,000 instead of custom design costing $8,000-$15,000. Check if your lot qualifies for ADU construction with address lookup tools /search before diving into planning.

Garage conversions cost $150-$200 per square foot in Arlington, making them the most budget-friendly option. You'll spend $60,000-$80,000 converting a standard 400-square-foot two-car garage into a studio apartment. This includes insulation, drywall, flooring, kitchen, bathroom, electrical upgrades, and HVAC installation. Foundation and roof work are minimal since you're using existing structure.

Detached new construction runs $200-$275 per square foot depending on finishes and complexity. A 600-square-foot detached ADU costs $120,000-$165,000, while an 800-square-foot unit ranges from $160,000-$220,000. These prices include concrete slab foundation, wood frame construction, composition shingle roof, vinyl or fiber cement siding, and standard finishes.

Attached additions split the difference at $175-$225 per square foot because you share one wall with the main house, reducing material and labor costs. A 500-square-foot attached unit runs $87,500-$112,500. You'll save $8,000-$12,000 on exterior walls but may need structural modifications to the main house, adding $5,000-$10,000 in engineering and permits.

Foundation type significantly impacts costs. Concrete slab costs $4-$6 per square foot, while pier and beam foundation runs $8-$12 per square foot. Gable roofs cost $8-$12 per square foot installed, but hip roofs add $3-$5 more per square foot. Standard vinyl plank flooring costs $6-$8 per square foot, while hardwood jumps to $12-$18 per square foot.

Labor accounts for 60-65% of construction costs in Arlington's competitive market. Framers charge $8-$12 per square foot, electricians run $4-$7 per square foot, and plumbers cost $15-$25 per fixture. Premium finishes like granite countertops ($60-$80 per square foot), custom cabinets ($150-$300 per linear foot), and tile showers ($25-$40 per square foot) can push costs toward the upper range quickly.

Arlington charges $3,000-$8,000 in total permit fees depending on ADU size and complexity. Base building permit fees start at $1,200 for projects under $50,000 and scale up to $2,800 for projects over $150,000. Plan review adds another $400-$800, while mechanical permits cost $150-$300, electrical permits run $200-$400, and plumbing permits cost $150-$350.

Impact fees vary by ADU size and utility demands. Water and sewer connection fees range from $1,500-$3,500 for new detached units, while garage conversions typically pay $500-$1,200 since utilities already serve the structure. School impact fees add $800-$1,500 per ADU, calculated based on square footage and estimated student generation rates.

Arlington waives certain fees for accessory structures under specific conditions, but most ADUs exceed the thresholds. Structures under 200 square feet without plumbing qualify for reduced fees around $400-$600 total, but functional ADUs need full bathrooms and kitchens. Trade permit fees are non-negotiable: electrical ($200-$400), plumbing ($150-$350), and HVAC ($150-$300).

Additional soft costs include fire department plan review ($200-$400 for units over 500 square feet), water meter fees ($800-$1,200 for new services), and inspection fees ($100-$200 per inspection with 4-6 inspections typical). Rush processing adds 50% to base permit fees but cuts approval time from 8-12 weeks to 4-6 weeks.

Texas cities set all ADU fees locally since no state legislation caps costs or mandates fee waivers. Arlington's fees remain competitive with surrounding suburbs. Dallas charges $4,000-$10,000 for similar projects, while Fort Worth runs $3,500-$9,000. Factor in 20% contingency for permit fees since requirements can change during review, especially for complex sites or non-conforming lots.

Architectural design costs $8,000-$15,000 for custom ADU plans in Arlington, or $2,000-$5,000 for pre-designed plans modified for your site. Custom design takes 6-10 weeks and includes site planning, floor plans, elevations, sections, and construction details needed for permitting. Pre-designed plans require 2-3 weeks for site-specific modifications like utility connections and setback compliance.

Structural engineering adds $2,000-$5,000 depending on foundation conditions and design complexity. Simple slab-on-grade foundations need basic engineering for $2,000-$3,000, while pier and beam or hillside construction requires extensive analysis costing $3,500-$5,000. Attached ADUs need structural review of the main house connection, adding $1,000-$2,000 to engineering costs.

Soils reports cost $800-$1,500 and take 1-2 weeks after drilling. Arlington's clay soils require special foundation design, making soils reports mandatory for most ADUs. Energy compliance calculations run $400-$800 to demonstrate your ADU meets International Energy Conservation Code (IECC) requirements for insulation, windows, and HVAC efficiency.

Property surveys cost $600-$1,200 and verify setbacks, easements, and lot coverage calculations. Your existing survey may work if it's less than 5 years old and shows current improvements. Topographic surveys add $300-$600 for sloped lots requiring grading and drainage design.

Professional fees total $12,000-$23,200 for full-service design and engineering, or $6,000-$12,000 using pre-designed plans with minimal engineering. Save money by purchasing plans from architects who specialize in Arlington ADUs and understand local codes. Many offer packages including permitting services for $1,500-$3,000 additional. Use cost calculators /tools/adu-eligibility to estimate professional fees based on your specific project size and complexity.

Site preparation costs $3,000-$8,000 for typical Arlington lots, starting with demolition and clearing. Concrete driveway removal runs $3-$5 per square foot, while tree removal costs $500-$2,000 per mature tree depending on size and location. Grading and drainage work ranges from $2-$4 per square foot for minor slopes up to $8-$12 per square foot for significant elevation changes.

Electrical panel upgrades cost $1,500-$4,000 since most existing homes need additional capacity for ADU loads. Standard 200-amp service upgrade runs $2,000-$3,000, while 400-amp service for large ADUs costs $3,000-$4,000. Trenching and conduit from main panel to ADU adds $8-$15 per linear foot depending on distance and obstacles.

Water line extension costs $25-$40 per linear foot including trenching, pipe, and backfill. Typical 50-foot runs cost $1,250-$2,000 from main house to detached ADU. Sewer connections run $35-$55 per linear foot, so a 60-foot connection costs $2,100-$3,300. Garage conversions often use existing water lines but need new sewer connections for bathrooms, costing $800-$2,000.

Gas line extensions cost $12-$20 per linear foot for appliances like water heaters, furnaces, or cooking ranges. A 40-foot gas line runs $480-$800 installed. Many Arlington ADUs use electric heat pumps instead of gas to avoid trenching costs, though operating expenses may be higher depending on utility rates.

Utility connection fees vary by provider. Oncor electric service costs $150-$300 for new meters, while Atmos Energy charges $200-$500 for gas connections. City water and sewer taps cost $1,500-$3,500 for new services, though garage conversions and attached ADUs typically use existing connections. Total utility costs range from $2,000-$6,000 for garage conversions up to $5,000-$12,000 for detached units requiring full utility runs.

Home Equity Line of Credit (HELOC) works best for ADU construction, offering $100,000-$400,000 credit lines at prime rate plus 0.5-2% (currently 8.5-10.5%). You pay interest only during construction, then convert to principal and interest payments. HELOCs require 15-20% home equity and debt-to-income ratios under 43%. Setup costs run $500-$1,500 with no prepayment penalties.

Cash-out refinancing provides lump-sum funding at mortgage rates (currently 7-8% for 30-year fixed) but requires refinancing your entire mortgage. Extract up to 80% of home value minus existing mortgage balance. A $400,000 home with $200,000 mortgage balance could access $120,000 for ADU construction. Closing costs run 2-3% of loan amount ($6,000-$12,000 on $300,000 refinance).

Construction-to-permanent loans finance ADU projects with single closing. Pay interest-only during 6-12 month construction period, then convert to 15-30 year mortgage. Rates start at prime plus 1-2% during construction (currently 9.5-10.5%), then convert to standard mortgage rates. Down payments range from 10-25% depending on lender and creditworthiness.

ADU-specific loan products from companies like Ygrene and Figure offer $50,000-$500,000 financing secured by your property. Rates range from 8-12% for 10-20 year terms with faster approval than traditional mortgages. Some products allow financing up to 90% of combined home and ADU value.

Personal loans work for smaller ADU projects under $100,000 but carry higher rates (10-15%) and shorter terms (3-7 years). Monthly payments on $75,000 personal loan at 12% for 5 years equal $1,668. FHA 203k renovation loans allow purchasing property and building ADU simultaneously but require owner occupancy and extensive documentation.

Studio ADUs (400-500 square feet) rent for $950-$1,300 monthly in Arlington, generating $11,400-$15,600 annual income. One-bedroom units (600-700 square feet) command $1,200-$1,650 monthly ($14,400-$19,800 annually), while two-bedroom ADUs (800-1,000 square feet) rent for $1,500-$2,100 monthly ($18,000-$25,200 annually). These rates reflect Arlington's proximity to Dallas employment centers and strong rental demand.

Return on investment varies significantly by construction type and rental income. A $75,000 garage conversion renting for $1,200 monthly generates 19.2% gross annual return before expenses. A $165,000 detached ADU renting for $1,650 monthly yields 12% gross return. Factor in 25-30% for vacancy, maintenance, property management, and taxes, reducing net returns to 13-14% and 8-9% respectively.

Simple payback periods range from 5-8 years for garage conversions and 8-12 years for new construction. A $85,000 studio conversion generating $950 monthly rent ($11,400 annually) pays back in 7.5 years. A $180,000 detached two-bedroom generating $1,800 monthly ($21,600 annually) takes 8.3 years to recover costs.

Property value increases from ADUs range from 50-75% of construction costs in Arlington's market. A $120,000 ADU typically adds $60,000-$90,000 to home value, creating immediate equity. Combined with rental income, total returns often exceed 15-20% annually for well-designed projects in desirable neighborhoods.

Arlington's job growth and limited housing inventory support strong ADU rental demand. Average days on market for ADU rentals run 15-25 days, compared to 30-45 days for traditional rentals. University of Texas Arlington students and healthcare workers from nearby Medical City Arlington provide consistent tenant pools willing to pay premiums for newer, private housing options.

Garage conversions save $50,000-$100,000 compared to new construction by using existing foundation, roof, and basic utilities. Converting a 400-square-foot garage costs $60,000-$80,000 versus $120,000-$160,000 for equivalent detached construction. You'll sacrifice parking but gain the fastest path to rental income with 3-4 month construction timelines.

Pre-approved ADU plans cost $2,000-$5,000 versus $8,000-$15,000 for custom design while cutting permit approval time from 12 weeks to 6-8 weeks. Arlington architects offer proven designs that meet local codes and setback requirements. Modify standard plans for $1,000-$2,500 to adjust window locations or room layouts rather than starting from scratch.

Avoid change orders that typically add 15-25% to construction costs. A $5,000 change order on $100,000 project triggers permit amendments ($400-$800), design revisions ($800-$1,500), and construction delays worth $2,000-$4,000 in extended financing costs. Lock in selections for flooring, fixtures, appliances, and finishes before construction starts.

Standard finishes keep costs at $150-$200 per square foot while premium upgrades push costs to $225-$275 per square foot. Choose vinyl plank flooring ($6-$8 per square foot) over hardwood ($12-$18), laminate countertops ($25-$35 per square foot) over granite ($60-$80), and standard fixtures rather than designer brands. Save $15,000-$25,000 on finishes for typical ADU.

Never cheap out on foundation, framing, roofing, or major mechanical systems since repairs cost more than proper installation. Spend extra for proper drainage ($1,500-$3,000), quality windows ($200-$400 each), and adequate insulation ($2-$4 per square foot) to avoid future problems. These investments pay back through lower utility bills and maintenance costs over 20-30 year ADU lifespan.