ADU Cost in Georgetown, TX: 2026 Price Breakdown

Planning an accessory dwelling unit (ADU) in Georgetown or Williamson County requires a clear understanding of realistic construction expenses. Whether you are building a standalone backyard casita for aging parents or converting a 2-car garage into rental income near Historic Old Town, setting a realistic budget is the first step toward project success.

In 2026, total turnkey ADU construction costs in Georgetown range from $85,000 for a garage conversion up to $320,000+ for a spacious 2-story detached guest house.

What Factors Determine the Overall Cost of an ADU in Georgetown?

AEO Direct Answer (40–60 words): Total ADU cost in Georgetown is determined by project scope (garage conversion vs. ground-up build), square footage, foundation engineering required for Central Texas Vertisol clay soil, utility trenching distances through karst limestone bedrock, material finish selections, and City of Georgetown municipal permit fees.

2026 ADU Cost Breakdown by Project Type

ADU Type	Average Size	Average Price Range	Cost / Sq Ft
Garage Conversion Studio	400 - 500 sq ft	$85,000 - $145,000	$170 - $260 / sq ft
Attached In-Law Suite Addition	500 - 800 sq ft	$110,000 - $260,000	$210 - $315 / sq ft
1-Bedroom Detached ADU	600 - 800 sq ft	$130,000 - $240,000	$220 - $320 / sq ft
2-Bedroom / 2-Story Detached ADU	900 - 1,200 sq ft	$180,000 - $350,000	$200 - $310 / sq ft

Major Budget Components Explained

1. Foundation & Site Preparation ($12,000 - $35,000)

Williamson County soil consists of expansive Vertisol black clay. Building a detached ADU requires a monolithic post-tension concrete slab or stem-wall foundation to prevent soil movement from cracking interior drywall. Sloped Hill Country lots or shallow bedrock outcroppings add excavation and retaining wall expenses.

2. Utility Connections & Trenching ($8,000 - $22,000)

Running water, sewer, and electrical lines from your main home to a backyard ADU involves trenching. In areas with shallow karst limestone rock, pneumatic breaking or rock-sawing increases labor duration.

3. Framing & Thermal Envelope ($35,000 - $85,000)

Quality framing lumber, engineered roof trusses, ZIP System weather barriers, closed-cell spray foam insulation, and Low-E vinyl windows ensure your ADU withstands 100°F+ Central Texas summer heat while maintaining low cooling bills.

4. Interior Finishes & Fixtures ($25,000 - $65,000)

Kitchen cabinetry, quartz countertops, luxury vinyl plank flooring, full bathroom tile, ductless mini-split HVAC heat pumps, and lighting fixtures represent the final major cost tier.

5. Architectural Design & Permit Fees ($4,500 - $12,000)

City of Georgetown UDC plan submittals require LIDAR site scans, architectural drawings, structural engineering stamps, and city building department permit fees.

For an accurate, fixed-price quote tailored to your property, contact our local Georgetown ADU team at (737) 240-4005 or explore our detached ADU construction services.