It’s never been easier—or more worthwhile—to add a second unit to your property.

Accessory Dwelling Units (ADUs) are everywhere in L.A.—and for good reason. Originally introduced as part of a broader effort to combat the housing crisis in Los Angeles, they’ve also created real opportunity for smart homeowners. They’re one of the smartest ways to increase property value, generate rental income, or create space for family. Zoning laws have made them far easier to build, but good planning still matters.

1. Attached or Detached?

• Attached ADUs are often cheaper and faster to permit, especially if plumbing or structural walls are shared

• Detached ADUs offer more privacy and long-term flexibility—ideal for rentals or multigenerational living

2. Design Priorities That Pay Off

• Keep it simple: rectangular footprints and gable or shed roofs often save money

• Prioritize natural light (skylights, transom windows) in tight lot conditions

• Use every inch wisely—built-ins, pocket doors, and high ceilings make a big difference

3. Costs to Expect in 2025

Construction costs in Los Angeles vary widely depending on site conditions, finishes, and permit complexity. On average:

• $250–$600 per square foot is a realistic range

• Lower-end builds may come in under $250/sq ft with basic finishes and flat lots

• High-end or complex builds (hillside, narrow access, heavy utility work) can exceed $600/sq ft

Also factor in soft costs: permit fees, Title 24 energy reports, soil reports, structural engineering, and plan checks. These can easily add $30,000–$60,000+ to your project.

4. Biggest Mistakes to Avoid

• Choosing pre-designed plans that don’t fit your site or style

• Underestimating sewer tie-in costs or utility panel upgrades

• Designing without thinking about privacy, both for you and your tenant

The Takeaway:

A well-built ADU isn’t just bonus space—it’s a future-proof strategy. Whether you’re housing loved ones, renting it out, or building for resale, investing in a smartly designed, legally permitted ADU can dramatically improve your property’s utility and value.