Doubling Down on Density: A Modern 2-Story ADU Duplex in Costa Mesa

In the heart of Orange County, homeowners are looking for smarter ways to utilize their land. Our latest project in Costa Mesa represents the gold standard of urban infill: a detached, two-story structure that houses two completely independent Accessory Dwelling Units (ADUs).

This project wasn't just about adding a "granny flat"—it was about creating high-quality, high-density housing that feels like a primary residence.

The Project Snapshot

Our client wanted to maximize the potential of their backyard while maintaining a footprint that didn't overwhelm the existing lot. We designed a sleek, vertical solution that offers privacy, efficiency, and modern aesthetics.

Feature	Specification
Location	Costa Mesa, CA
Structure Type	Detached 2-Story Building
Unit Count	1 per level
Layout	2 Bedrooms / 2 Bathrooms per unit
Square Footage	720 Sq. Ft. per unit (1,440 total)

Intelligent Design in 720 Square Feet

Designing a 2-bedroom, 2-bathroom floor plan within a 720-square-foot footprint requires surgical precision. Our goal was to eliminate "dead space" (like long hallways) and prioritize the common areas where residents spend the most time.

• The Upper Level: Features vaulted ceilings to create an airy, expansive feel, making the 720 square feet feel significantly larger.

• The Lower Level: Utilizes a seamless transition to the outdoors, perfect for the coastal Costa Mesa climate.

• Privacy First: By stacking the units, we were able to preserve more yard space and strategically place windows to ensure neither the ADU tenants nor the main house residents feel overlooked.

Navigating the OC Regulatory Landscape

Whether it’s in Costa Mesa, Los Angeles, or San Diego, navigating local building codes and tenant improvement requirements is what we do best. For this project, we ensured full compliance with California’s latest ADU laws, which have become increasingly favorable for multi-unit ADU structures on single-family lots.

From structural engineering to ensuring the utilities were properly scaled for two additional households, our professional drawings paved the way for a smooth permitting process.

Why This Model Works

This "stacked ADU" approach is a game-changer for Southern California property owners. It provides:

1. Double the Rental Income: Two units mean two revenue streams.

2. Multigenerational Living: Ideal for housing extended family while maintaining independent living spaces.

3. Property Value: High-quality, permitted 2-bedroom units are among the most sought-after additions in the Orange County real estate market.

   
   

Ready to Transform Your Backyard?

Whether you are located in Orange County, San Diego, or Los Angeles, our firm specializes in the professional drawings and architectural planning needed to bring these complex projects to life.

If you have a vision for a residential or commercial tenant improvement project, let’s build something incredible together. Contact us today to discuss your site's potential.