ADU in Hillsborough | Case Study | Oria Builders
| Project Type | ADU |
|---|---|
| Location | Hillsborough, CA (Tobin Clark Estate) |
| Investment | $250,000 - $300,000 |
| Duration | 3 months |
| Completed | 2023-08-15 |
The Challenge
The homeowners in Hillsborough’s prestigious Tobin Clark Estate neighborhood approached us with a clear vision: they wanted to add a fully functional, modern ADU to their property. The goal was to create a space that could serve as a guest house for visiting family or as a rental unit for additional income. However, designing an ADU in Hillsborough comes with unique challenges. The neighborhood’s architectural character leans heavily toward timeless, high-end designs, and any addition needed to blend seamlessly with the existing structures to maintain property value. On top of that, Hillsborough has strict local building codes and zoning restrictions, including limitations on lot coverage, height, and setbacks. The homeowners also had concerns about maintaining privacy for both the main house and the new ADU. They wanted a space that felt independent yet connected, luxurious yet practical. Finally, they needed a reliable construction company in Hillsborough that could navigate the complex permitting process and deliver on their vision without delays.
Our Approach
Our team started with a comprehensive site evaluation to understand the property’s layout, existing utilities, and zoning constraints. In Hillsborough, ADU projects require detailed planning to comply with local ordinances, and we worked closely with the homeowners to develop a design that met their needs while adhering to these rules. During several design meetings, we presented 3D renderings to help the homeowners visualize the final product. We handled the permit application process from start to finish, ensuring that every detail — from utility connections to fire safety compliance — was accounted for. Hillsborough's permitting process typically takes 6–8 weeks, and we used this time to finalize material selections, including custom finishes that complemented the main home’s aesthetic. The homeowners opted for premium materials such as wide-plank hardwood flooring, quartz countertops, and energy-efficient windows. We also incorporated thoughtful landscaping around the ADU to create a sense of privacy and harmony with the surrounding environment.
Build Process
Construction began with the demolition and preparation of the site. Hillsborough’s sloped terrain required us to level the foundation carefully and install proper drainage systems to ensure long-term durability. Once the foundation was poured, framing went up quickly, and we kept the homeowners updated with weekly progress reports and walkthroughs. The interior build-out included custom cabinetry, high-end appliances, and a luxurious bathroom with porcelain tile and a frameless glass shower. We also installed energy-efficient lighting and a mini-split HVAC system to ensure year-round comfort. Throughout the project, we coordinated with city inspectors to keep everything on schedule. Hillsborough’s inspection process can sometimes cause delays, but our pre-planning ensured that all inspections were approved on the first pass. Finally, our team paid close attention to the exterior, applying a smooth stucco finish that matched the main home. The landscaping included native plants and a small patio area, providing a serene outdoor space for future occupants. The project was completed on time and within the agreed budget, with no surprises along the way.
Scope of Work
- Site preparation and foundation work
- Complete framing and roofing installation
- Installation of energy-efficient windows and doors
- Custom cabinetry and quartz countertop installation
- Bathroom build-out with porcelain tile and frameless glass shower
- Landscaping and exterior stucco finish
Materials & Features
- Wide-plank hardwood flooring
- Quartz countertops (Carrara White)
- Energy-efficient windows (dual-pane, Low-E glass)
- Porcelain tile bathroom flooring and walls
- Mini-split HVAC system for energy-efficient heating and cooling
- Custom cabinetry with soft-close hinges
Results
- Increased property value by an estimated $200,000
- Added 600 square feet of livable space to the property
- Achieved energy savings of 15% due to efficient design
- Project completed on time with zero change orders
Project Highlights
- Completed the project within the planned 3-month timeline
- Seamless integration with the architectural style of the main home
- Achieved all permits with no delays in Hillsborough's strict zoning process
- Delivered a luxurious, modern space that exceeded homeowner expectations
Client Testimonial
"Oria Builders brought our vision to life with incredible attention to detail. The ADU feels like a natural extension of our property, and the team made the entire process stress-free."
— Michael R., Homeowner in Hillsborough
Frequently Asked Questions
How long did this ADU project take?
The ADU project in Hillsborough was completed in 3 months. This included site preparation, construction, inspections, and final touches.
What was the total investment for this project?
The investment for this ADU project was between $250,000 and $300,000. The cost included premium materials, custom finishes, and compliance with Hillsborough’s stringent building codes.
Did the homeowner need to move out during construction?
No, the homeowner did not need to move out. Since the ADU was built as a standalone structure, construction had minimal impact on the main house.
What permits were required for this project in Hillsborough?
The project required permits for grading, foundation, electrical, plumbing, and fire safety compliance. We handled the entire permitting process, which took approximately 6–8 weeks.