A two -story tributary residential unit (ADU) can increase the value of your Adu Permit In San Diego property. Whether you want a personal suite for over -living, rental unit, or family, vertical housing opens the doors of new possibilities - if your land is small if your land is small.
But two-story ADU has unique designs, zoning and cost ideas. In this guide, we will give you every important information from height limit to cost, so that you can decide whether it is right to build for you or not.
1. What Is a 2 Story ADU?
A two-story ADU is a secondary residential unit with two levels, built either:
- Detached from your main home
- Attached to the side or back
- Above a garage or existing structure
The main advantage? You get more square footage without expanding your area - it is ideal for tight urban plots or limited yard location properties.
2. Why Make a Two Storey ADU in San Diego?
Maximize Your Location
Instead of spreading, you construct - saving outer space for bagches, courtyards or parking.
Better Views & Light
The second floor often means better natural light and visual, especially in coastal or mountainous regions.
Area of Living
You can dedicate one floor to bedrooms and the second floor to a meeting, dining room and kitchen - allowing it to look like a full house.
3. California State Applied Law
The basis of permissible things has been determined in the State ADU Act of California (Government Code § 65852.2):
- Rights Approval for code-influence adus
- Height Boundary Base Line: 16 feet for separate ADU, but more allowed when connected near transport or main house.
- Low Setback: only 4 feet distance from the lines of the side and back property
- No Requirement of Minimum Lot Size
- Streamlined Permit: 60-day review period for full applications
4. San Diego-Specific Height & Zoning Rules
San Diego’s municipal code builds on state law. For two-story ADUs, here’s what matters most:
- Detached flat-roof ADUs: Up to 21′ tall
- Detached sloped-roof ADUs: Up to 30′ tall
- Attached ADUs: Must follow the same height limits as the main home
- Over-garage builds: Height measured from the ground to the highest point of the roof
- Setbacks: At least 4′ from side and rear; front setbacks vary by zone
- Lot coverage: Your ADU plus existing structures must fit within allowed coverage limits
Tip: Always check your property’s zoning map before designing.
5. Popular 2 Story ADU Designs in San Diego
Carriage House ADU
A living unit above a garage—parking stays on the first floor, living space above. Works well on narrow lots.
Stacked ADU
Two self-contained units stacked vertically—possible if you want dual rentals or a multigenerational setup.
Split-Level Attached ADU
An addition that blends with your main home’s architecture, sharing one or more walls.
6. Costs of Building a 2 Story ADU in San Diego
Two-story builds cost more per square foot than single-story because of:
- Extra structural requirements
- Stairs and landings
- Added scaffolding and framing complexity
Typical costs:
- Cost per sq ft construction: $ 300 - $ 350 for vertical construction
- Cost per square foot turnky (including design, permit and finish): $ 375– $ 415
- Example: 1,000 square -foot two -storey adu can range from $ 375,000 to $ 415,000
7. The Permitting Process for a 2 Story ADU
8. How Long Does It Take?
- Design and Planning: 1–3 months
- Permit Review: 2-3 months (State law says 60 days, but modifications often extend it)
- Construction: 6-9 months for two-storey construction
9. Special Considerations for 2 Story ADUs
Structural Engineering
Second floors need stronger foundations and framing. Over-garage units require load-bearing upgrades.
Privacy Concerns
The second floor windows may show a view of neighbors - so plan obstacles, frost -covered glass or strategic landscapes.
Accessibility
Two stories mean stairs. Consider whether your intended residents can use them for a long time.
10. Utility and Infrastructure Requirements
- Draws and Sewer: Additional bathroom/kitchen may need to dig or upgrade to handle the kitchen
- Electrical: Full equipment and HVAC may require capacity upgradation
- Water Supply: Larger units sometimes require new meters
11. Financing a 2 Story ADU
Common options include:
- Home equity loans or HELOCs
- Cash-out refinance
- Construction loans
- Specialized ADU financing programs
12. Common Mistakes to Avoid
- Designing without checking local height rules
- Underestimating costs of structural reinforcement
- Forgetting to account for stair footprint in floor plans
- Overlooking privacy issues with neighboring properties
13. FAQ: 2 Story ADUs in San Diego
14. Final Thoughts
A two -storey adu in San Diego can double your place without surrounding your yard. Before starting, it is important to understand the local height range, structural needs and costs.
By working with experienced adu professionals and completing the permit process strategically, you can maximize your investment - and enjoy a versatile, functional place for the coming years.
