ADU Permit Guide for Arlington, Texas — Step-by-Step Process (2026)

Before you spend a dime on architects or contractors, verify you can legally build an ADU on your property. Arlington treats ADUs as accessory structures under their Unified Development Code, and several basic requirements must be met.

You need proof of property ownership through a warranty deed or title policy dated within 90 days. The property must contain an existing legal dwelling that serves as the primary residence. Properties with code violations or outstanding permits cannot proceed until those issues are resolved.

Check your zoning designation using Arlington's online mapping tool /search. ADUs are permitted in R-10, R-5, and R-7 single-family zones but prohibited in multifamily zones, commercial areas, and planned unit developments (PUDs). If your property sits in a PUD, review the specific development agreement—some allow ADUs while others don't.

Order a title report from your title company ($200-$400) to identify any deed restrictions or easements that could prevent ADU construction. Many Arlington neighborhoods built after 1980 have homeowners association (HOA) covenants that prohibit accessory dwelling units, even if the city allows them. The city won't override private deed restrictions.

Properties in flood zones require additional FEMA compliance documentation. Use Arlington's flood zone map to determine if your property sits in a 100-year or 500-year flood plain. Flood zone properties need elevation certificates and special foundation designs, adding $2,000-$5,000 to permit costs.

Historic properties face additional restrictions. While Arlington has fewer historic districts than Dallas or Fort Worth, properties built before 1950 in established neighborhoods may require historical review. Contact the Planning Department at 817-459-6100 to verify if your property has historical designations.

Properties with existing pools, large accessory buildings, or extensive impervious coverage may lack space for an ADU while maintaining required setbacks and lot coverage ratios. Arlington limits total lot coverage to 40% in most residential zones, including the primary house, ADU, driveways, and other structures.

Arlington requires specific setbacks and dimensional standards that eliminate many potential ADU locations. In R-10 zones, ADUs need 10-foot rear setbacks, 5-foot side setbacks, and 25-foot front setbacks. R-5 and R-7 zones have slightly different requirements: 10-foot rear, 5-foot side, and 20-foot front setbacks respectively.

Use Arlington's setback calculator /tools/setback-calculator or hire a surveyor ($800-$1,200) to verify buildable area. Many properties appear suitable until precise measurements reveal setback violations. Corner lots face additional challenges with dual front setbacks that significantly reduce buildable space.

Maximum ADU size is 1,200 square feet or 50% of the primary dwelling's floor area, whichever is smaller. Height limits are 25 feet with pitched roofs or 20 feet for flat roofs. These restrictions often surprise property owners planning larger units.

Contact Arlington's Planning Department for a pre-application meeting. While not mandatory, these 30-minute sessions ($150 fee) can identify deal-breaker issues before you invest in architectural plans. Schedule meetings online through Arlington's permit portal or call 817-459-6777. Bring your survey, preliminary sketches, and specific questions about setbacks, utilities, or zoning interpretations.

Utility capacity verification is essential but often overlooked. Contact Atmos Energy (gas), Oncor (electric), and Arlington Water Utilities to confirm service capacity for an additional dwelling. Some older neighborhoods lack adequate infrastructure for additional gas or electrical loads. Water and sewer capacity issues are less common but can occur in areas with aging infrastructure.

Check for utility easements on your property survey. Major utility lines often run through rear yards with 10-15 foot easements that prevent building placement. Underground utility marking (call 811) is free but only shows approximate locations—surveyed utility locations cost $300-$600 but provide precise measurements.

Tree preservation requirements can derail ADU projects in established neighborhoods. Arlington's tree ordinance protects trees over 8 inches in diameter. Removing protected trees requires permits and mitigation that may not be feasible on smaller lots.

Arlington requires comprehensive construction documents prepared by licensed architects or engineers. Pre-drawn plans from national companies rarely meet Arlington's specific requirements and code interpretations, leading to expensive revisions during plan review.

Your plan set must include a detailed site plan showing property boundaries, existing structures, proposed ADU location, setback dimensions, utility connections, drainage flow, and landscape features. Include all trees over 6 inches in diameter with species identification. Show parking spaces—Arlington requires one covered parking space per ADU bedroom, separate from primary dwelling parking.

Architectural plans need floor plans, exterior elevations from all four sides, building sections, and construction details. Show room dimensions, ceiling heights, window and door schedules, and fixture locations. Include storage areas—ADUs under 1,000 square feet must provide 10% of floor area in storage space.

Structural calculations are required for all ADUs, prepared by Texas-licensed structural engineers. Generic foundation and framing plans won't pass review. Soil conditions in Arlington vary significantly due to expansive clay soils common throughout North Texas. Most ADUs require engineered foundations with specific pier depths and reinforcement.

Energy compliance follows the 2018 International Energy Conservation Code (IECC) with Texas amendments. Your plans must show insulation R-values, window U-factors, HVAC equipment efficiency ratings, and duct sealing details. Manual J load calculations are required for HVAC sizing—oversized or undersized equipment will fail inspection.

Electrical, plumbing, and mechanical plans must be drawn by licensed Texas engineers or prepared by licensed contractors with plan-stamping authority. Show panel locations, circuit routing, fixture connections, and equipment specifications. Include voltage drop calculations for electrical runs over 100 feet.

Plan preparation costs range from $8,000-$15,000 for architect-designed ADUs or $3,000-$6,000 for contractor-prepared plans using licensed engineers for structural and MEP components. Budget 6-10 weeks for initial plan preparation, longer if multiple design revisions are needed.

Submit electronic plans through Arlington's online permit portal /tools/codes/arlington. Plan files must be PDF format, maximum 25MB per file, with clear title blocks showing project address, designer contact information, and drawing dates.

Arlington accepts ADU permit applications through their online Build Arlington portal, accessible 24/7 at buildarlington.com. In-person submissions are handled at City Hall, 101 W Abram Street, but online submission is faster and provides automatic receipt confirmation.

The complete application package includes the ADU Permit Application (Form BP-2021), property survey, architectural plans, structural calculations, energy compliance documentation, and drainage/grading plan. Missing documents trigger automatic rejection without review.

Application fees total $3,200-$8,400 depending on ADU size and complexity. The base building permit fee is $2,800 for ADUs under 800 square feet, $3,600 for 800-1,200 square feet. Add $400 for plan review, $200 for electrical permit, $150 for plumbing permit, $150 for mechanical permit, and $100 for gas permit. Properties requiring drainage studies pay an additional $500-$1,500.

Fill out the application completely—incomplete forms delay processing by 2-3 weeks. List the correct property owner as shown on tax records. Contractor information must include Texas contractor license numbers and insurance certificate numbers. Property description must match the legal description from your survey exactly.

Valuation declarations affect permit fees and future property taxes. Underestimating construction costs may trigger red flags during review. Arlington expects ADU valuations of $150-$275 per square foot depending on finishes and complexity. A 1,000 square foot ADU should show construction values of $150,000-$275,000.

Submit detailed construction schedules showing start dates, milestone completions, and final completion dates. Permits expire 180 days after issuance if construction hasn't started, though extensions are available for $200.

Property owner affidavits are required for owner-builder permits but most ADU projects exceed DIY capabilities. Licensed contractors must provide Texas contractor license numbers, workers compensation coverage, and general liability insurance certificates with minimum $500,000 coverage.

Upload all documents in a single session—partial applications cannot be saved in the portal. Print your confirmation receipt showing application number, submission date, and payment confirmation. This receipt is required for all future correspondence with the Planning Department.

After submission, your application enters Arlington's multi-department review process taking 6-12 weeks for initial review. The Planning Department assigns a case number and begins technical review within 5-7 business days of submission.

Four departments review ADU applications simultaneously: Building Safety (structural, code compliance), Development Services (zoning, setbacks), Public Works (drainage, utilities), and Fire Prevention (access, safety systems). Each department can generate plan check comments requiring corrections.

Expect plan check comments on your first submission—90% of ADU applications require corrections. Common comments include missing structural details, incomplete energy compliance calculations, setback dimension clarifications, and drainage plan modifications. The city emails detailed correction lists typically 2-4 pages long.

Response time for corrections is 30 days from the comment letter date. Extensions are available but require written requests before the deadline. Resubmission follows the same online process as initial applications but uses your existing case number.

Second review takes 3-4 weeks if corrections are minor, longer for significant changes. Major modifications like relocated buildings or increased size restart the full review process. Budget 2-3 correction cycles for most ADU projects.

Building officials may request additional documentation during review: updated surveys for setback verification, geotechnical reports for foundation design, or utility capacity letters from service providers. These requests extend review timelines by 2-6 weeks depending on required documentation.

Stay responsive during review—failure to respond to correction letters within 30 days results in application cancellation and full fee forfeiture. Maintain regular contact with your case reviewer through the online portal messaging system.

Complex ADU projects involving drainage modifications, utility relocations, or tree removal permits may require interdepartmental coordination meetings. These meetings can extend review timelines by 4-8 weeks but resolve multiple issues simultaneously.

Track application status through the Build Arlington portal showing real-time review progress, comment letters, and approval status by department. Most ADU permits receive approval after 4-6 months from initial submission.

Once your ADU permit is approved, you have 180 days to start construction or the permit expires. Schedule your pre-construction meeting with Arlington's Building Safety Division within 10 days of permit issuance. This meeting reviews inspection schedules, site safety requirements, and specific project conditions.

Arlington requires 12 standard inspections for ADU construction: footing, foundation, framing, electrical rough-in, plumbing rough-in, mechanical rough-in, insulation, drywall, electrical final, plumbing final, mechanical final, and certificate of occupancy final.

Schedule inspections through the online portal or by calling 817-459-6245 before 3:00 PM for next-day inspection. Emergency inspections are available for $100 additional fee. Inspectors arrive between 8:00 AM and 5:00 PM—no specific time appointments are available.

Foundation inspections occur before concrete pours. Inspectors verify proper excavation depth, rebar placement, anchor bolt locations, and plumbing sleeve installations. Have your structural drawings and rebar placement sheets available during inspection.

Framing inspection covers structural lumber sizes, connection hardware, beam spans, and code-required blocking. Inspectors measure room dimensions, ceiling heights, stair construction, and window/door rough openings. Cover electrical and plumbing work at this stage.

Rough-in inspections for electrical, plumbing, and mechanical systems happen after framing approval but before insulation. Each trade requires separate inspection appointments. Inspectors test system functionality, verify code compliance, and check proper installation methods.

Insulation inspection must occur before drywall installation. Inspectors verify R-values, proper installation techniques, air sealing, and vapor barrier placement. Energy code compliance is strictly enforced—incorrect insulation fails inspection.

Final inspections test complete system operation, verify fixture installation, and confirm code compliance. Schedule final inspections after all finish work is complete but before occupancy. Failed final inspections require correction and re-inspection fees of $75 per trade.

Inspection failures are common—budget time for corrections and re-inspections. Typical failure reasons include missing blocking, incorrect fixture installations, incomplete electrical connections, and improper ventilation. Re-inspection scheduling adds 2-5 days to project timelines.

After passing all required inspections, schedule your Certificate of Occupancy (CO) final inspection. This comprehensive review verifies the ADU matches approved plans and meets all code requirements for safe occupancy.

The CO inspection covers life safety systems, egress window operation, smoke detector functionality, HVAC system operation, and utility connections. Inspectors verify address numbers are visible, parking spaces are completed, and landscaping meets plan requirements.

Arlington issues Certificates of Occupancy within 5 business days of passing final inspection. The CO authorizes legal occupancy and rental of your ADU. Operating without a valid CO violates city code and may result in fines up to $500 per day.

Address assignment for ADUs follows Arlington's addressing standards. Most ADUs receive secondary addresses (like 123 Main St. #B) unless separate street access allows primary addressing. Submit address requests during the CO process—this takes 2-3 weeks.

Utility connections require separate applications with each provider after CO approval. Arlington Water Utilities charges $450 for new meter installation plus monthly service fees. Electric and gas connections typically cost $200-$800 depending on distance from existing services.

Contact the Tarrant County Appraisal District within 30 days of CO issuance to report the new dwelling. This ensures proper property tax assessment and establishes the ADU's legal status. Failure to report new construction may result in penalties during future appraisal reviews.

Update your homeowner's insurance policy to include ADU coverage before allowing occupancy. Most insurance companies require notification of additional dwelling units and may adjust premiums based on rental income potential.

Record the ADU with Tarrant County deed records if you plan to sell the property. While not required immediately, recorded ADUs provide clear documentation for future property transfers and financing.

Setback violations cause 40% of ADU application rejections in Arlington. Property owners frequently miscalculate distances from property lines or fail to account for easements that effectively increase setback requirements. Corner lots are especially problematic with dual front yard setbacks. Always hire a licensed surveyor ($800-$1,200) to verify buildable area before designing your ADU.

Incomplete or inadequate construction drawings delay 60% of applications by 4-8 weeks. Plans missing structural calculations, energy compliance documentation, or MEP details cannot proceed through review. Generic plans purchased online rarely meet Arlington's specific requirements. Budget $8,000-$15,000 for properly prepared plans by Texas-licensed professionals.

Utility capacity issues surprise many property owners in older Arlington neighborhoods. Inadequate electrical service, insufficient water pressure, or lack of gas service capacity can halt projects requiring expensive infrastructure upgrades. Contact all utility providers during pre-planning to verify service availability and capacity for additional dwelling units.

HOA covenant violations kill projects even after city approval. Many Arlington subdivisions built after 1980 have deed restrictions prohibiting ADUs, rental properties, or accessory buildings exceeding specific sizes. Review your HOA covenants and architectural control committee requirements before applying for permits. The city cannot override private deed restrictions.

Tree preservation conflicts delay projects in established neighborhoods where mature trees occupy optimal ADU locations. Arlington's tree ordinance protects trees over 8 inches in diameter, requiring removal permits and expensive mitigation. Some protected trees cannot be removed regardless of mitigation offers, effectively eliminating ADU construction in those locations.

Drainage and flooding concerns halt projects on properties with inadequate stormwater management. Arlington requires detailed drainage studies for most ADU projects, adding $2,000-$5,000 to costs and 4-6 weeks to review timelines. Properties in flood zones need FEMA elevation certificates and specialized foundation designs increasing costs by $10,000-$25,000.

Fire department access requirements can eliminate ADU feasibility on properties with restricted access or narrow driveways. ADUs must be within 150 feet of fire truck access, with minimum 20-foot clear width access routes. Properties with circular drives, narrow lots, or significant grade changes may not meet fire access standards regardless of setback compliance.