San Diego is a city where property space is often limited but demand for additional living space keeps growing. In response, many homeowners are turning to two-story accessory dwelling units (ADUs) as a creative solution. These multi-level units make the most of small lots while offering added value, functionality, and privacy.
San Diego 2 Story ADU Guide for Homeowners
Whether you’re thinking about building an in-law suite, a guest house, or a rental unit, this guide will help you understand everything about two-story ADUs in San Diego from design ideas to permit requirements and costs.
What Is a Two-Story ADU?
A two-story ADU is a secondary residential unit built on the same property as a main home, spread across two levels. It includes essential living areas like a kitchen, bathroom, bedroom, and sometimes even a garage or storage space.
Unlike one-story ADUs, the vertical layout allows homeowners to keep more of their yard while still gaining considerable square footage. This makes them an excellent option for lots with limited width or depth.
Why Choose a Two-Story ADU in San Diego?
Two-story ADUs offer both space efficiency and lifestyle flexibility. Given San Diego’s competitive housing market and compact lot sizes, these units have become increasingly popular.
Key benefits include:
- Preserved outdoor space
You retain room for gardens, patios, or play areas by building vertically. - Greater privacy
Living and sleeping areas can be separated between floors. - More design possibilities
Lofts, balconies, and even ocean-view windows are options on the upper level. - Attractive for renters
Multi-level units appeal to tenants seeking space and privacy. - Added resale value
A well-built ADU can improve overall property appeal.
Design Considerations for Two-Story ADUs
Designing a two-story unit involves more complexity than a single-story build. You’ll need to take into account everything from stair placement to rooflines and structural engineering.
1. Height Limits and Zoning
Most residential lots in San Diego allow ADUs up to 25–30 feet tall, but local zoning laws vary by neighborhood. Historic areas or communities with strict height restrictions may require special approval.
Be mindful of:
- Side and rear setbacks
- Floor area ratio (FAR) limitations
- Proximity to property lines
2. Staircase Design
The staircase takes up interior space, so it should be placed carefully. Common choices include:
- Straight stairs for ease of use
- L-shaped stairs to save space and add style
- Spiral staircases for compact layouts
3. Light and Ventilation
Natural light becomes even more important in multi-level layouts. Large windows, sliding glass doors, and skylights help prevent dark corners and create a more open feel.
4. Foundation Strength
A second story requires a stronger base. Soil testing, deeper footings, and reinforced foundations are essential. Nestadu’s team ensures all structural work meets California building code and earthquake safety standards.
San Diego Permit Process for Two-Story ADUs
San Diego’s housing laws are ADU-friendly, but two-story units still require formal permits and inspections. Understanding the process helps avoid delays or compliance issues.
Steps typically include:
- Feasibility Study
Site evaluation to determine if a two-story ADU is allowed. - Design and Drafting
Plans must meet San Diego building codes and be submitted to the city. - Permit Submission
Drawings and documents go through city review. This may take several weeks. - Construction and Inspections
Building begins after approval, with inspections at key phases. - Final Approval
Once construction is complete and passes inspection, you’ll receive a Certificate of Occupancy.
Nestadu handles this full process on your behalf, ensuring everything moves smoothly from concept to completion.
Cost of Building a Two-Story ADU in San Diego
Building a two-story ADU is a significant investment, but it also provides long-term returns through rental income or property appreciation.
Estimated cost range: $300,000 to $500,000+
What affects the final cost?
- Size and square footage
Larger ADUs cost more to build and finish. - Site conditions
Sloped lots or poor soil may require extra preparation. - Interior finishes
Flooring, cabinetry, and fixtures all influence price. - Utility connections
Separate plumbing and electrical systems may be required. - Permit and design fees
These are typically included in Nestadu’s transparent pricing model.
We offer complete cost breakdowns before starting any build so there are no financial surprises down the road.
Common Uses for Two-Story ADUs
Two-story ADUs aren’t just about adding extra square footage they also adapt to a wide range of living needs.
Popular use cases include:
- In-Law Suite
Provide aging parents with independence and privacy. - Guest House
Perfect for visitors, grown children, or weekend getaways. - Rental Property
Earn monthly income with long-term or short-term tenants. - Work + Live Units
Home office on the first floor, bedroom above. - Creative Studios
Art, music, or fitness studios can occupy one of the levels.
With flexible layouts and thoughtful design, Nestadu helps you create a space that works for your life.
Why San Diego Homeowners Choose Nestadu
Nestadu is a trusted name in ADU construction throughout California. Our team combines hands-on experience with local building knowledge to craft units that look beautiful and function smoothly.
Here’s what you can expect from us:
- Detailed site analysis before any work begins
- Custom design options that match your home’s style
- Help with permits, regulations, and zoning
- High-quality materials and workmanship
- Clear communication from start to finish
We don’t just build ADUs we build spaces where families can live, grow, and thrive.
Final Thoughts
Two-story ADUs offer a smart solution for adding space and value to your San Diego property without sacrificing your backyard. From multigenerational living to rental income, these units serve a wide range of purposes.
Nestadu specializes in designing and building two-story ADUs that complement your home, meet city regulations, and match your lifestyle. If you’re ready to explore the possibilities, our team is here to guide you through every step of the process.
Ready to build up, not out?
Contact Nestadu today and let’s talk about your two-story ADU in San Diego.
Frequently Asked Questions
Q: 1 Can I build a two-story ADU on a small lot?
A. Yes. Two-story ADUs are ideal for small or narrow properties.
Q: 2 Is a two-story unit more expensive than a one-story?
A. Generally, yes. The structure and foundation require more material and labor.
Q: 3 Do I need parking for an ADU in San Diego?
A. In many zones near transit, parking requirements are waived.
Q: 4 How long does construction take?
A. From planning to final inspection, most builds take 8–12 months.
Q: 5 Can I rent out my two-story ADU?
A.Yes. ADUs are legal to rent in San Diego, though short-term rentals may have specific rules.
