As the Principal Architect at Ten Seventy Architecture, I'm excited to share the completion of our Feather ADU Development project - a strategic infill development that demonstrates how thoughtful design can significantly contribute to San Diego's housing supply while maintaining quality and livability.
Project Overview: Maximizing Housing Impact
The Feather Development transforms a single-family property with a large backyard into a five-unit residential complex. By adding two duplex ADU structures behind the existing home, we've successfully added four new housing units to San Diego's housing stock - a meaningful contribution to addressing our ongoing housing crisis.
What makes this project particularly noteworthy is our responsible use of the ADU Bonus Program. While we're utilizing this program to achieve the additional density, we're not abusing it. We're genuinely adding four new units while ensuring that 25% of the new units (one quarter) will be rented at affordable rates, fulfilling the program's intent to provide both market-rate and affordable housing options.
Modern Design with Practical Considerations
The project features a contemporary architectural approach with several key design elements:
Duplex Configuration
Rather than creating triplexes or larger structures, we deliberately chose to build two duplexes. This decision provides several advantages:
- More exterior space for each unit, which is highly valued in San Diego's climate
- Simpler construction process and coordination
- Reduced permit fees through the use of combination permits, which are ideal for these types of infill development projects
Unit Layout and Features
Each duplex consists of:
- First floor: One bedroom, one bathroom unit with direct access to a large patio
- Second floor: One bedroom, one bathroom unit with vaulted ceilings and a cantilevered balcony
Despite being compact at 500 square feet each, the vaulted ceilings on the second story create a sense of spaciousness that makes these units feel much larger than their actual footprint.
Thoughtful Interior Design
Each unit includes:
- A large walk-in closet that maximizes storage in the compact layout
- Galley kitchen designed for efficiency
- Three-quarter bathroom (no tub) to keep plumbing fixture counts manageable and reduce costs
Technical and Construction Challenges
Sound and Fire Separation
One of the critical technical aspects of stacked units is ensuring proper separation between floors. We incorporated:
- One-hour fire rating in the floor assembly between units
- 50 Sound Transmission Class (STC) rating to minimize noise transfer
- 50 Impact Isolation Class (IIC) rating to prevent impact sounds from being transmitted to the unit below
These specifications ensure that tenants in the lower units don't hear footsteps or other sounds from the units above - a crucial consideration for tenant satisfaction and retention.
Structural Engineering Innovation
One of the most significant design challenges was the cantilevered balconies on the second-floor units. These balconies extend eight feet without any supporting posts, creating clean lines and maximizing the usable outdoor space. This required extensive coordination with our structural engineer to ensure both safety and aesthetic goals were met.
Utility Coordination
The project required several utility upgrades:
- Water meter upgrade, which necessitated a right-of-way permit
- Installation of a multi-meter system for the fourplex units
- Early coordination with SDG&E for electrical connections
As our contractor Jesse Stoner from Urban Builders notes, getting SDG&E involved as early as possible is crucial because utility connection processes can take much longer than expected.
Construction Excellence and Collaboration
The project was completed at approximately $375 per square foot, demonstrating that quality modern ADU construction can be achieved at reasonable costs when approached strategically.
Jesse Stoner from Urban Builders, our general contractor partner, highlighted several factors that contributed to the project's success:
Design Efficiency
The four identical units and simple shed roof design (with water flowing from one side) made construction straightforward and efficient. This repetition allows contractors to develop a rhythm and reduce both time and costs.
Collaborative Process
One aspect I'm particularly proud of is our hands-on approach throughout the construction process. Rather than simply delivering drawings and walking away, our team remains actively involved, providing quick responses to questions and requests for information. This collaboration ensures that our design intent is properly executed and any field conditions are addressed promptly.
Exterior Design and Materials
The exterior features an all-stucco finish that achieves the required one-hour fire rating while maintaining a contemporary aesthetic. We implemented a two-tone color scheme that adds visual interest and reflects modern design sensibilities without overwhelming the neighboring properties.
The clean lines, cantilevered balconies, and thoughtful proportions demonstrate that ADU development doesn't have to compromise on architectural quality. These structures enhance rather than detract from the neighborhood character.
Project Outcomes and Impact
The Feather Development demonstrates several important principles:
- Housing Impact: Four new housing units in an established neighborhood without requiring new infrastructure
- Affordability Component: Responsible use of the ADU Bonus Program to provide both market-rate and affordable housing
- Design Quality: Modern, well-designed units that residents will be proud to call home
- Construction Efficiency: Thoughtful design that allows for cost-effective construction
Lessons for Future Projects
This project reinforces several key strategies for successful ADU development:
- Early utility coordination is essential - start the SDG&E process as early as possible
- Repetition in design can significantly reduce construction costs and complexity
- Proper sound and fire separation is crucial for stacked units
- Outdoor space remains highly valuable in San Diego's climate
- Collaborative relationships between architect, contractor, and client create the best outcomes
Looking Forward
The Feather Development represents the kind of thoughtful infill development that San Diego needs more of. By working within existing neighborhoods and adding quality housing units, we can begin to address our housing crisis without the need for massive infrastructure investments or sprawling development.
At Ten Seventy Architecture, we're committed to continuing this type of work - creating modern, efficient housing solutions that contribute meaningfully to our community while maintaining the design excellence our clients expect.
If you're considering an ADU project or exploring the possibilities of the ADU Bonus Program for your property, I'd be happy to discuss how we can help you achieve your goals while contributing to San Diego's housing solution.
For more information about our ADU design services or to discuss your specific project, you can schedule a consultation with me.