Building a 2-Story ADU in East LA: Expert Insights from the Field

As housing demand continues to rise across California, many homeowners are turning to Accessory Dwelling Units (ADUs) as a smart investment and practical solution. At Ataman Studio, we recently collaborated with Ortiz General Builders on a unique garage conversion project in East Los Angeles, transforming an outdated structure into a fully functional two-story ADU. Here’s an in-depth look at how we tackled the project — from design and permitting to construction and costs — along with expert advice for anyone considering building an ADU in California.

Why ADUs Are Still a Smart Investment in 2025

Whether you’re looking to create extra living space for family, generate rental income, or boost your property’s value, building an ADU makes sense. In LA’s competitive housing market, converting underutilized space — like a garage — into a self-contained home can yield long-term financial benefits. In this project, for example, the homeowner invested approximately $180,000 and stands to rent out the new ADU for up to $2,500/month, all while paying only $1,200/month on a loan. That’s positive cash flow from day one.

Project Overview: From Garage to 2-Story ADU

• Location: East Los Angeles.
• Type: Garage conversion + second-story addition.
• Size: ~800 sq ft total (garage/laundry on 1st floor + 1-bedroom ADU above).
• Timeline: Estimated 6–8 months.
• Initial Budget: $180,000.
• Final Cost (with foundation fixes): ~$192,000.
• Rental Value: $2,200–$2,500/month.
• Property Value Increase: $380,000–$400,000.

This project highlights the potential of maximizing your property’s value and rental income through smart ADU design and construction. Converting an existing garage and adding a second story can be a cost-effective way to add living space and generate passive income, especially in high-demand areas like East Los Angeles.

If you’re considering a similar project, our team at Ataman Studio specializes in garage conversions and full ADU design services tailored to California’s building codes and your specific needs.

Design & Planning: Start with Realistic Goals

Before construction begins, it’s crucial to have detailed architectural and engineering plans. Clients often ask, “How much does it cost to build an ADU in California?” — but without a floor plan, it’s nearly impossible to give an accurate estimate.

A rough estimate for standard one-story ADUs ranges from $250–$300 per square foot, while two-story ADUs tend to cost $50–$75 more per square foot due to additional structural requirements like deeper foundations and reinforced framing.

💡 Pro Tip: Work with an experienced home design team that includes architects, structural engineers, and permitting experts to avoid costly delays.

Foundation Surprises: What Lies Beneath

In this project, a major challenge came early on: the original garage foundation was inadequate, with a concrete slab only 2.5–3 inches thick in places. Our team had to demolish the entire base and pour a new, fully reinforced foundation. The process, including engineering revisions, city inspections, and concrete work, added ~$12,000 to the budget and took about 6 weeks.

👉 Expert Tip: Hire a contractor to perform a preliminary foundation inspection or core drilling before design is finalized. Though it adds a small upfront cost, it could save you thousands later.

The Construction Process: Step by Step

Here’s how we broke the project down:

1. Demolition & Preparation
   • Removed 99% of the original structure
   • Preserved one wall to maintain legal setbacks (critical in tight LA lots)
2. Foundation Work
   • Full rebar-reinforced slab
   • Pre-inspections to reduce risk of rework
3. Framing & Structural Build
   • Used heavy-duty 2×14 lumber for strength
   • Completed framing in-house to control costs
4. Plumbing, Electrical & Inspections
   • Installed new utility lines (~80 ft of trenching)
   • Passed rough inspections quickly thanks to updated plans
5. Interior & Finishes (in progress)
   • Standard materials to keep budget manageable
   • Option to upgrade finishes for higher-end rentals

Costs Beyond the Build: Don’t Forget Utilities

When budgeting your ADU, remember that utility hookups often add significant costs beyond the base construction price. For example, trenching and installing gas, water, and electric lines for this project—about 40 feet from the main house—cost between $30,000 and $40,000. This includes concrete cutting, inspections, and coordination with the city.

Utility expenses can vary widely depending on your property’s layout and local requirements, so planning early is key to avoiding surprises.

To better estimate your total costs, try our ADU Cost Calculator. It helps you factor in utilities and other expenses so you can plan your project with confidence.

Timeline: What to Expect

Delays usually come from:

• Unforeseen site conditions (like foundation issues).
• Slow permit processing or inspection scheduling.
• Custom material lead times.

One-Story vs Two-Story ADU: Which Is Better?

💬 Expert Take: Two-story ADUs are great for small urban lots where footprint is limited. One-story builds are cheaper and faster if you’ve got backyard space to spare.

How to Save Money When Building an ADU

Building an ADU can be a smart investment, but costs can quickly add up without careful planning. Here are key strategies to control your budget without sacrificing quality:

Stick to Standard Finishes: Choosing basic yet durable kitchens, flooring, and fixtures can save tens of thousands of dollars. Standard materials are widely available, easier to install, and often come with warranties, reducing long-term maintenance costs.

Keep the Layout Simple: Opt for an open floor plan with one bedroom and one bathroom. Simple, efficient layouts minimize framing, plumbing, and electrical complexity, which lowers labor and material expenses. Complex floor plans or multiple rooms increase costs exponentially.

Leverage Existing Structures: If possible, convert an existing garage or underutilized space into your ADU. Garage conversions avoid the need for new foundations and framing, which are among the most expensive parts of construction. This approach speeds up the project and reduces permit complexities.

Avoid Custom Elements Unless Budget Allows: Custom kitchens, unique architectural features, or high-end finishes can significantly raise costs. These are worthwhile only if your budget comfortably covers them. Otherwise, focus on standard designs that maximize function and durability.

Implementing these strategies early in the design phase can help you stay within budget and avoid costly changes during construction. For a personalized estimate and cost-saving tips tailored to your property, check out our ADU Cost Calculator.

Conclusion: Should You Build an ADU in 2025?

Absolutely. Whether you’re a homeowner looking to house family or an investor planning to generate rental income, an ADU is one of the smartest property upgrades you can make. With proper planning, the right design team, and a skilled builder, your project can be profitable, efficient, and compliant with California ADU regulations.

Note: All prices and cost estimates are provided based on 2025 data and may vary depending on project scope and location.

Ready to Start Your Own ADU Project?

At Ataman Studio, we offer full-service design, floor plans, engineering, and permitting for all types of ADUs — from garage conversions to custom-built two-story units. We specialize in home design in California, with expertise in LA City and LA County permits.

Contact us today to get your ADU project started right.