Historic ADU with Pool and Large Bonus Space
Idaho Street, San Diego, CA
Homeowner Story: Flex space
Other Features: Poolside
Special Circumstance: Historic Home
ADU Video TourCreating a Historic ADU in San Diego’s University Heights
This project showcases how thoughtful design can bring a historic ADU to life while respecting the character of an original Spanish Eclectic (Spanish Colonial Revival) home. Located in one of San Diego’s most architecturally rich neighborhoods, the homeowners set out to maximize their property’s potential, add flexible living space, and create a true backyard retreat.
This project achieves a rare balance: the ADU clearly belongs on the property, yet it stands on its own architecturally. It’s a model for how historic ADUs in San Diego can meet preservation requirements while still delivering contemporary comfort and flexibility.
Balancing Preservation and Modern Living
The existing 1929 residence features hallmarks of the Spanish Eclectic style: white stucco walls, a mix of flat parapet and red clay tile gable roofs, and asymmetrical massing. When it came time to add an accessory dwelling unit, the project went through historic review, which required the new construction to remain visually distinct from the original home while still complementing it.
The resulting ADU follows a Contemporary/Modernist approach: clean lines, an L-shaped plan, a flat parapet roof, and smooth white stucco. These choices echo the massing and materials of the main house without replicating its decorative elements.
A Flexible and Functional Layout
The 1200 SF L-shaped ADU was constructed with matching white stucco and a flat roof, mirroring the architectural style of the main home. The result is a cohesive, beautifully integrated backyard compound that not only elevates the homeowner’s lifestyle but also adds long-term value and flexibility to the property.
The unit offers a spacious two-bedroom, one-bathroom layout with an additional bonus room area. This flexible space easily adapts to the homeowners’ changing needs, serving as a home office, TV lounge, and home gym. By planning for multifunctional use from the outset, the design ensures the ADU remains valuable for decades to come.
An Outdoor Oasis Between Old and New
The ADU is positioned to shape a private backyard compound shared with the historic home. Between the two structures, the homeowners created a lush, resort-like space complete with palm trees, a plunge pool, multiple seating areas, and even a putting green. This outdoor environment blurs the line between indoor and outdoor living, adding both lifestyle and property value. Read more about adding a pool alongside an ADU.
Floor Plan:
2BR/1BA 32×21 Long
Community:
The City of San Diego ADU Guide
With more than 70 ADU projects completed or in progress throughout the City of San Diego, we’ve seen firsthand how the city’s regulations create opportunities that are not available in many other jurisdictions.
One of the biggest differentiators is San Diego’s Affordable ADU Bonus Program, which allows qualifying properties to add multiple ADUs when some units are rented at affordable rates. This has made San Diego a leader in ADU development and has opened the door for homeowners and investors to create additional housing beyond what is typically allowed under state law.
In 2025, the city became the first jurisdiction in San Diego County to adopt AB1033, allowing qualifying ADUs to be sold separately from the primary residence. As of June 2026, only the County of San Diego and the City of San Diego have adopted AB1033.
San Diego also offers significant flexibility in the types of ADUs that can be built. The city allows two-story ADUs, ADUs with garages, ADUs with guest quarters, ADUs with rooftop decks, front yard ADUs, and stacked ADUs for multi-unit projects. We’ve worked on all of these project types throughout the city.
Another unique aspect of San Diego is its setback regulations. Many single-story ADUs can be built with 0-foot side and rear setbacks, creating opportunities on properties where space is limited. However, building too close to property lines can trigger additional fire-rating requirements and construction challenges, which is why thoughtful site planning remains critical even when the regulations appear flexible.
San Diego ADU Permitting
Most ADU permits in the City of San Diego are approved within approximately 3 to 5 months after submission, although timelines vary depending on project complexity and city workload.
Compared to many other jurisdictions in San Diego County, the City of San Diego has some of the highest ADU permit fees. Permit costs often range from approximately $26-$28 per square foot, though smaller ADUs under 500 square feet can benefit from reduced fees closer to $14 per square foot. We maintain a detailed breakdown of City of San Diego permit fees, including plan check fees, building permit fees, impact fees, and inspection fees, in our ADU permit fee guide.
Approximately 10% of our City of San Diego projects are located within the Coastal Zone. While coastal properties often raise concerns for homeowners, many ADUs qualify for exemptions from Coastal Development Permit requirements under the City’s updated Local Coastal Program. Learn more about building an ADU in the Coastal Zone.
Working with an experienced ADU builder helps identify potential permitting requirements early and creates a more predictable path through design and permitting.
