San Diego County ADU Guide
San Diego homeowners guide to ADUs. Learn what an ADU is, why they make sense now, costs, benefits, and how to build one the right way.
Accessory Dwelling Units (ADUs)—also known as granny flats, backyard homes, casitas, in- law suites, or guest houses—have become one of the most powerful tools for San Diego homeowners looking to add space, flexibility, and long-term value.
With California’s progressive ADU laws and San Diego’s continued housing demand, building an ADU is no longer a niche idea—it is a practical, future-focused investment. Whether you are planning for multigenerational living, rental income, or lifestyle flexibility, this guide will help you understand what’s possible, what it costs, and how to do it right.
At Murray Lampert Design, Build, Remodel, we have helped San Diego homeowners make smart remodeling decisions for over 50 years. This guide reflects real-world experience, not theory.
What Is an ADU—and Why Build One in San Diego?
An ADU is a fully independent living space located on the same property as a primary residence. It includes its own kitchen, bathroom, sleeping area, and separate entrance.
ADUs in San Diego can take many forms:
- Detached backyard homes
- Garage conversions
- Attached additions
- Basement or lower-level suites
Why San Diego Homeowners Are Building ADUs
San Diego faces ongoing housing pressure driven by limited land, rising home prices, and strong rental demand. ADUs offer a solution that benefits both homeowners and the community— without changing neighborhood character.
For homeowners, ADUs provide:
- Long-term rental income
- Housing for aging parents or adult children
- Increased property value
- Lifestyle flexibility without moving
Why ADUs Make Sense in San Diego Right Now
California Has Removed Many Barriers
California’s statewide ADU laws override many local restrictions, making ADUs easier to build than ever before. In San Diego:
- ADUs are allowed on most single-family and multi-family lots
- Parking requirements are often waived
- Setback requirements are reduced
- Permitting timelines are faster
San Diego now treats ADUs as a key housing strategy, not an exception.
Multigenerational Living Without Compromise
ADUs allow families to stay connected while maintaining privacy and independence.
Common use cases include:
- Aging parents who want to remain close but independent
- Adult children transitioning back home
- Live-in caregivers
- Long-term guests
Instead of sacrificing comfort—or paying for assisted living—families can create a dignified, permanent solution right at home.
Put Your Low Mortgage to Work
Many San Diego homeowners refinanced before interest rates rose and now hold mortgages well below current rates.
Rather than selling and re-buying at today’s rates, ADUs allow you to:
- Stay in your home
- Unlock equity
- Add usable living space
- Increase long-term property value
An ADU often makes more financial sense than moving—especially in coastal and central San Diego neighborhoods.
San Diego ADU Regulations: What You Need to Know
San Diego follows California state law while adding local guidelines.
Key San Diego ADU Rules (General Overview)
- Number allowed:
- One ADU + one Junior ADU (JADU) per single-family lot
- Up to two ADUs on -multi-family properties (more in some cases)
Size limits:
- Detached ADUs: up to 1,200 sq ft
- Conversions: allowed up to existing structure size
Setbacks:
- As little as 4 feet for conversions
- Reduced setbacks for new detached units
Parking:
- Often not required, especially near transit
Rentals:
- Long-term rentals allowed
- Short-term rentals subject to separate rules
Because zoning, overlays, and lot conditions vary widely, site-specific review is critical—this is where experience matters.
Types of ADUs in San Diego
Detached ADU
A standalone backyard home offering maximum privacy and flexibility. Best for long-term rentals or family housing.
Garage Conversion ADU
One of the most cost-effective options, especially common in San Diego. Ideal when parking requirements are waived.
Attached ADU
An addition connected to the main home, designed as a self-contained unit.
Junior ADU (JADU)
A smaller interior unit (typically under 500 sq ft) carved out of existing space.Each option has different cost, zoning, and design considerations.
How Much Does It Cost to Build an ADU in San Diego?
ADU costs vary based on size, type, finishes, and site conditions.
Typical San Diego ADU Cost Ranges
- Garage conversion ADU: $180,000 – $300,000
- Attached ADU: $250,000 – $400,000
Detached ADU: $350,000 – $600,000+
Major Cost Drivers
- Site access and grading
- Utility connections and upgrades
- Coastal or hillside regulations
- Structural upgrades
Finish level and material quality
A realistic budget and early planning are essential to avoid surprises.
Financing Options for San Diego ADUs
Common financing strategies include:
- Home equity loans or HELOCs
- Cash-out refinances
- Renovation loans
Construction loans
Rental income potential often offsets monthly carrying costs, especially in high-demand neighborhoods.
The Design-Build Advantage
ADUs succeed or fail in the planning stage.
As a true design-build firm, Murray Lampert integrates:
- Architectural design
- Interior design
- Permitting
- Construction All under one roof. This approach:
- Reduces redesign and delays
- Keeps budgets aligned with reality
- Improves communication
Protects quality and craftsmanship
We design ADUs that feel intentional—not like afterthoughts.
The ADU Process: What to Expect
- Clarify goals – family, rental, flexibility, or future planning
- Site and zoning review – confirm feasibility
- Design development – layout, architecture, interiors
- Permitting – managed by our in-house team
- Construction – quality-driven, phased, and transparent
- Final inspection and occupancy
No shortcuts. No guesswork.
Why Work With Murray Lampert Design, Build, Remodel
- Over 50 years in San Diego
- In-house architecture and interior design
- A+ BBB rating since 1976
- Award-winning service
Proven design-build process
We are not the lowest-cost option—and that is intentional. Our clients value durability, transparency, and getting it right the first time.
Let’s Talk About Your ADU Goals
If you are considering an ADU in San Diego, the smartest first step is a conversation—not a commitment.
We will help you:
- Understand what is possible on your lot
- Evaluate costs and risks
Decide whether an ADU truly aligns with your goals
No pressure. Just clarity.
Schedule a consultation with Murray Lampert Design, Build, Remodel today.
• City & County ADU Official Resources
City of San Diego (Primary ADU Info & Permitting)
City of San Diego ADU Information & Toolkit — overview, requirements, and general guidance for building ADUs in the City of San Diego. City of San Diego ADU Information & Toolkit
City of San Diego ADU/JADU Permit Bulletin — permit requirements and process details. San Diego ADU/JADU Permit Guide (Info Bulletin 400)
San Diego Housing Commission ADU Finance Program — financing assistance for eligible homeowners (City of San Diego). SDHC ADU Finance Program
San Diego County (Unincorporated Areas & Countywide Policy)
San Diego County ADU Zoning Ordinance & Info — official county ADU regulations. San Diego County ADU Zoning & Regulations
San Diego County ADU Handbook (PDF) — detailed county guidance on ADU requirements. San Diego County ADU Handbook (PDF)
• Incorporated Cities in San Diego County (Local ADU Pages)
City of Chula Vista
Chula Vista ADU Official Page — city permitting info, standard plans, checklists. City of Chula Vista Accessory Dwelling Unit Info
City of Carlsbad
City of Carlsbad ADU Permit & Program — ADU permit-ready plans and resources. Carlsbad ADU Permit Ready Program & Info
San Diego County (Unincorporated Areas)
City/County Planning & Development Services — Accessory Dwelling Units (ADUs) Official ADU resources for properties in unincorporated San Diego County, including eligibility and guidelines for detached, attached, and JADUs. County of San Diego+1
https://www.sandiegocounty.gov/content/sdc/pds/bldg/adu.html
County ADU Handbook (PDF) — detailed overview and procedural steps. County of San ** ** Diego
https://www.sandiegocounty.gov/content/dam/sdc/pds/bldg/adu_info/COSD_ADU_Handbook.p df
Incorporated Cities in San Diego County (Planning/ADU Departments)
City of San Diego
City Planning Department — Accessory Dwelling Units (ADU & JADU)
Overview of ADU rules, zoning, and policy direction in San Diego. sandiego.gov
https://www.sandiego.gov/planning/work/housing/toolkit/accessory-dwelling-units
City of San Diego ADU/JADU Information Bulletin — official permit requirements and process details. sandiego.gov
https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400
City of Encinitas
Encinitas Development Services – Accessory Dwelling Units (ADUs)
City-specific ADU overview with definitions, JADU guidance, and local standards. Encinitas
Encinitas ADU Permits & Application Info — permit checklists and compliance docs. Encinitas
City of Escondido
Escondido ADU Resource Page (Planning/Development Services)
Official local ADU overview with planning and building requirements. escondido.gov
https://www.escondido.gov/238/Accessory-Dwelling-Units
Escondido Pre-Approved ADU (PAADU) Program — downloadable pre-approved plans and resources. escondido.gov
https://escondido.gov/1207/Pre-Approved-ADU-Program-PAADU
City of Oceanside
City of Oceanside — Accessory Dwelling Unit (ADU) Planning Page
Official zoning, codes, and construction planning information for Oceanside ADUs. Oceanside City Website
https://www.ci.oceanside.ca.us/government/development-services/planning/accessory-dwelling-unit-adu
City of Chula Vista
Chula Vista Development Services — Accessory Dwelling Units
Official ADU permit info including checklists and standard plan options. Chula Vista
City of La Mesa
City of La Mesa – Accessory Dwelling Units
Local ADU guidebook, development overview, and permit information. cityoflamesa.gov
https://www.cityoflamesa.gov/1821/Accessory-Dwelling-Units
General Notes for Other Cities
Many other San Diego County cities host ADU requirements through their planning or community development departments. If a city does not maintain a dedicated ADU page, residents should refer to its Planning/Development Services section. (Examples include: Carlsbad, Coronado, Del Mar, El Cajon, Imperial Beach, Lemon Grove, National City, Poway, San Marcos, Santee, Solana Beach, Vista.)
San Diego County ADU Planning & Permit Resources (By City)
Tip: ADU rules vary by jurisdiction. Use the links below to confirm requirements for your property’s city (or unincorporated County area).
Unincorporated San Diego County (County of San Diego – PDS)
City of San Diego
Carlsbad
Chula Vista
Coronado
Del Mar
El Cajon
Encinitas
Escondido
Imperial Beach
La Mesa
Lemon Grove
National City
Oceanside
Poway
San Marcos
Santee
Solana Beach
Vista
Murray Lampert Design, Build, Remodel, a San Diego design-build remodeling and construction firm serving the area since 1975. For more information about how Murray Lampert is helping homeowners navigate the current building environment, visit www.murraylampert.com or call (619) 848-1433.