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How Much Does It Cost to Build an ADU in Los Angeles in 2025?

Introduction:

Accessory Dwelling Units (ADUs) — also known as backyard homes, casitas, or granny flats — remain one of the most powerful ways to add value, flexibility, and income potential to your Los Angeles property. But how much does it actually cost to build one in 2025? Whether you’re building for family, rental income, or resale value, understanding the real costs is crucial before getting started.


Let’s break it all down.


  1. ADU Costs Broken Down: Design, Permits, and Construction


ADU projects typically range between $150,000 and $350,000+ in Los Angeles, depending on size, type, and level of finish. Here’s a typical cost breakdown:


Design & Architecture Fees


• Site review, as-builts, schematic design, construction drawings, and permitting

• Range: $8,000 – $25,000+

• Factors: hillside lots, garage conversions vs. new builds, zoning hurdles


Permits & City Fees


• Includes plan check, school fees, utilities, and sometimes sewer connection upgrades

• Range: $5,000 – $15,000+

• Each LA municipality (e.g., Glendale, Pasadena, Long Beach) has its own fee structure


Construction Costs


• Garage Conversion: $150,000 – $225,000


• Detached ADU (400–800 sf): $250,000 – $350,000+


• High-end or complex builds: $350,000+


• Major drivers: access to utilities, soil conditions, existing structure, finish level


  1. Here’s what a typical ADU project timeline looks like:


Design & Planning

1–2 months


City Plan Check & Permitting

3–6 months


Construction

6-9 months (can widely vary)


Total time from start to finish: 10-17 months

Expect longer timelines for hillside sites, historic properties, or cities with slower permitting departments.


  1. Common Mistakes to Avoid


Building an ADU in Los Angeles isn’t always simple. Here are some pitfalls to watch for:


  • Underestimating soft costs: Design, permits, and consultant fees can add up quickly


  • Ignoring site constraints: Setbacks, slopes, or utility easements may limit your design


  • Choosing the cheapest contractor: Low bids often lead to change orders, delays, or quality issues


  • Lack of coordination: Failing to involve your architect during construction can result in costly mistakes


  1. How Drury Architects Can Help


At Drury Architects, we’ve guided numerous clients through successful ADU projects — from first-time homeowners in Highland Park to investors in Echo Park. Here’s what makes us different:


• Tailored Solutions: Every site and family is unique. We don’t do cookie-cutter plans.

• Hands-On Guidance: We help you navigate zoning rules, city submittals, and contractor bids.

• Build-Ready Deliverables: We create clear, coordinated drawing sets that make permitting smoother and help your contractor stay on budget.


Whether it’s a detached backyard unit, a garage conversion, or a two-story live/work ADU, we help you turn complexity into clarity — and ideas into reality.


Thinking About Building an ADU? Contact Us for a Quick Consult.


Let’s talk about your site, your goals, and your budget — and map out a plan that works for you. Your ADU project deserves a strong foundation, and it starts with the right team.


Call us at (213) 584-3119 or email at rob@druryarchitects.com


Drury Architects Inc. | Architecture for Living Well in Los Angeles

 
 
 

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