Your Complete Guide to Accessory Dwelling Units in San Diego
1. Introduction
San Diego faces a serious housing shortage. The median home sold in 2024 was over 43 years old, and more than 71% of homes are over 30, far above the U.S. average (Axios). As property values soar and average rent hits $3,175/month in San Diego, more homeowners are turning to accessory dwelling units (ADU) as flexible, affordable housing options.
Whether you’re looking to create a rental unit, support multigenerational living, or increase property value, this guide covers everything you need to know—from accessory dwelling unit plans and zoning rules to choosing an Accessory Dwelling Unit contractor and securing a building permit in San Diego.
2. What Is an Accessory Dwelling Unit (ADU)?
An accessory dwelling unit is a self-contained residential space located on the same lot as a primary dwelling. It can be detached or attached, with its own entrance, kitchen, bathroom, and living area. In San Diego, ADUs can be up to 1,200 sq ft, depending on the type and lot.
Types of ADUs in San Diego
- Detached Accessory Dwelling Unit: A separate building—often a backyard unit—up to 1,200 sq ft and 16 ft tall, allowed with zero setbacks. Taller units require 4-ft side/rear setbacks.
- Attached ADU: A structure that shares a wall with the main house. Same size limits apply.
- Garage conversions: Existing garages can be converted into secondary housing units, often exempt from some setback or size limits.
- Interior conversions: These include Junior ADUs (JADUs) up to 500 sq ft that share a bathroom with the primary residence.
These housing options provide flexible solutions for homeowners and renters alike.
3. A Few San Diego ADU Regulations to Keep in Mind
Size & Setbacks
- Maximum size: 1,200 sq ft for new ADUs. Interior conversions are exempt and can add 150 sq ft for access.
- Height rules: ≤16 ft requires no setbacks; taller ADUs need 4-ft side/rear setbacks.
- Zoning compliance: Front and street-side yard rules follow base zoning, but one ≤800 sq ft Accessory Dwelling Unit may encroach slightly (sandiego.gov).
Parking Rules
- No additional parking required outside coastal or designated overlay zones.
- SB 2097 eliminates parking requirements near transit stops, increasing feasibility for Accessory Dwelling Unit development.
Permits & Fees
- No minimum lot size or density limits for ADUs.
- Many development impact fees are waived, though bonus ADUs for affordable housing may still incur enhancement fees.
- Minimum Accessory Dwelling Unit size is 150 sq ft.
- A thorough building inspection and compliance with the building code are required during the permitting process.
4. Why Build an ADU in San Diego?
- Rental relief: With average rents around $2,571/month, ADUs offer a more affordable rental unit solution.
- Investment: An Accessory Dwelling Unit can cost $100K–$300K to build and generate long-term income.
- Lifestyle: Great for multigenerational living, home offices, or downsizing on your own property.
- Flexibility: Ideal for hosting family or providing a temporary living space if you ever need to vacate your main home due to emergencies.
5. Accessory Dwelling Unit Plans
Selecting the right Accessory Dwelling Unit plan depends on lot size, goals, and zoning requirements:
- Detached 1 bed/1 bath ADU (~500–800 sq ft): Ideal for backyard spaces.
- Two-story ADUs (~1,000–1,200 sq ft): Maximize space; requires 4-ft setbacks and height compliance.
- Garage conversions: Lower cost and often faster approval.
6. Why Choose H&L Studios for Your ADU Project?
Building an Accessory Dwelling Unit in San Diego isn’t just about construction—it’s about creating a space that works for your lifestyle, your property, and your long-term goals. At H&L Studios, we combine design-forward thinking with deep knowledge of local permitting and build logistics to deliver a turnkey solution from concept to completion.
Here’s what sets us apart:
- Design + Build Expertise: We bring together thoughtful design and seamless project execution. That means your ADU will be functional and beautiful.
- Local Know-How: We’ve worked through the San Diego permitting process and understand how to avoid common delays.
- Full-Service Project Management: From material sourcing and cost planning to subcontractor quality control, we handle it all.
- Client-Centered Process: We customize every project to your needs—whether it’s a rental unit, guest space, or multigenerational home.
To make sure your ADU is tailored to your goals, we’ll start with a few key questions:
- What’s the primary purpose of your Accessory Dwelling Unit? (Rental income, family use, guest space, etc.)
- Do you have an ideal layout or square footage in mind?
- Are there any features or amenities that are important to you (e.g., full kitchen, laundry, accessibility, storage)?
- What’s your ideal timeline and budget range?
- Have you already consulted with an architect or do you need design support from the ground up?
7. What Does It Cost to Build an ADU with H&L Studios?
While exact costs will vary depending on the size, design, and site conditions, our team will help you understand what’s realistic for your budget from day one. Most clients can expect their Accessory Dwelling Unit investment to fall within a broad range, and we’ll walk you through options that align with your goals.
We also help you explore financing solutions—whether through home equity, ADU-specific loans, or available local assistance programs—and guide you through every step of the process so there are no surprises along the way.
Every Accessory Dwelling Unit project varies in scope, so get multiple estimates to find the best value.
8. Timeline: From Planning to Move-In
- Design & consultation: 1–2 months
- Permitting & approvals: 2–4 months (faster with pre-approved plans)
- ADU construction: 4–8 months depending on complexity
- Total time: ~6–12 months
9. Frequently Asked Questions (FAQ)
Q1: Do I need a permit to build an ADU?
Yes, you’ll need a building permit and may need planning or utility permits.
Q2: Can I build more than one ADU?
Yes—state law allows multiple ADUs in some cases, especially when adding bonus units for affordable housing.
Q3: Can I use my ADU as a short-term rental?
Long-term rentals are allowed. Short term rentals may face restrictions based on zoning or HOA rules.
Q4: Will my property taxes increase?
Yes, but typically only for the secondary housing unit, not your entire property.
10. Final Thoughts & Next Steps
ADUs are reshaping the way San Diegans think about housing options, offering affordability, flexibility, and income opportunities. Whether you’re a property owner looking to support family, generate income, or increase real estate value, an Accessory Dwelling Unit can be a smart move.
Ready to get started?
We’d love to partner with you on this journey. At H&L Studios, we’ll guide you through the entire process—from initial planning and design all the way through construction and completion.
Next Steps:
- Fill out our inquiry form to tell us more about your property and goals.
- Schedule your free consultation by emailing our team at info@handlstudios.com.
- Start exploring design concepts and timelines tailored to your vision.
Let’s bring your ADU project to life, click here to get in touch with us and take the first step.
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