San Diego ADUs 101 – A Beginner’s Guide for Homeowners

What Is an ADU in San Diego?

An Accessory Dwelling Unit (ADU) is a home that is either attached or separate from the main house on the same property. It has its own kitchen, bathroom, and living area, allowing people to live independently.

If you’re a San Diego homeowner thinking about adding more space or creating rental income, you’ve probably come across the term ADU. But what exactly does it mean, and why has it become such a hot topic in recent years?

At the state level, California calls ADUs and their smaller versions, JADUs, “an innovative and effective option for adding much needed housing” (CA HCD ADU Handbook). The state uses these units in its long-term plan to fix the housing shortage. It makes it easier for homeowners to build extra housing on existing lots.

The growth in San Diego has been especially striking. In 2023, ADU permits nearly tripled to 1,907, constituting almost 20% of all new housing permits citywide (San Diego Union-Tribune). This surge shows just how important ADUs have become as a flexible solution for families and a vital part of the city’s housing supply.

Location matters — check your lot size, zoning, and utilities early to confirm if your property qualifies for an ADU.

Why Build an ADU?

Homeowners build ADUs to increase property value, generate rental income, and create flexible living space for family or guests. In San Diego’s competitive housing market, these benefits make ADUs a practical solution. They help with long-term equity and everyday needs.

Adding an ADU to your property isn’t just about creating extra space — it’s one of the smartest investments a San Diego homeowner can make. ADUs can increase your property value. They can also provide steady rental income. They offer both financial and lifestyle benefits.

Key Benefits of Building an ADU

• Equity & Resale Value: “An ADU can add approximately 25–30% to property values on average.” (Waymaker Realty)
• Rental Income Potential: In 2023, one-bedroom units averaged $2,245, two-bedroom units averaged $2,857, studios averaged $1,929, and three-bedroom units averaged $3,651 in San Diego County. (AOAUSA – San Diego Market Update)
• Family Flexibility: Perfect for multigenerational living, ADUs give homeowners the ability to house aging parents, provide independent space for adult children, or create a private guest suite — all while keeping loved ones close.

Think long-term — ADUs increase property value, provide rental income, and create flexible family living options.

Can I Build an ADU on My Property?

Yes — most San Diego homeowners can build at least one ADU. City rules say a single-family lot can add one ADU and one Junior ADU (JADU). Multifamily lots can add up to two detached ADUs plus conversions.

Thanks to California’s ADU-friendly laws, almost every single-family homeowner in San Diego can build one. Here’s what you need to know about eligibility and how many units are allowed. (City of San Diego, Bulletin 400)

Key Eligibility Rules

Single-Family Homes:

• 1 detached or attached ADU
• 1 conversion ADU (garage or interior space)
• 1 JADU (≤500 sq. ft., within existing house)
• Total possible: up to 3 units (main home + ADU + JADU)

Multifamily Properties:

• Up to 2 detached ADUs
• Multiple conversion ADUs from unused interior space (like storage rooms or garages)

State-Level Protection: “One ADU up to 800 sq ft may be built even if it exceeds the max FAR (floor area ratio).”

Do a feasibility check early — confirming zoning, utilities, and setbacks ensures your lot qualifies before investing.

How to Start an ADU Project in San Diego

To start an ADU in San Diego, homeowners should check property eligibility, set a budget, design or select plans, submit for permits, build, and complete final inspections. The City of San Diego also provides pre-approved plans to speed up the process.

Building an ADU may feel overwhelming at first, but breaking it into clear steps makes the process more manageable. Here’s a straightforward roadmap to get you started, based on city requirements and expert guidance.

Step-by-Step Process

• Research Zoning & Feasibility: Confirm your property qualifies for an ADU. By law, single-family lots in San Diego can build one ADU and one JADU (City of San Diego).
• Budget & Financing: Establish how much you can spend and explore financing options. The San Diego Housing Commission offers loans up to $250,000 with technical assistance (SDHC).
• Design & Select Plans: Work with a designer or use the city’s Standard ADU Building Plans (pre-approved) to save time and fees (San Diego DSD).
• Submit Permit Application: “A Building Permit is required to create an ADU or JADU. There are no exemptions.” (City of San Diego, Bulletin 400)
• Construction & Inspections: Once permits are issued, construction can begin. Expect the build to take several months, with required inspections along the way.
• Final Occupancy: After passing inspections, you’ll receive a Certificate of Occupancy, making your ADU legal and move-in ready.

Start strong — budgeting and design decisions in the early phase have the biggest impact on timeline and cost.

Permits & Requirements (What You Need to Know)

To build an ADU in San Diego, homeowners must obtain a building permit, follow city design rules, and comply with state timelines. The city requires all ADUs to go through permitting, but California law caps review time at 60 days.
Before breaking ground on your ADU, you’ll need to secure the right permits and meet city and state requirements. Fortunately, San Diego has streamlined the process to encourage more homeowners to build.

Key Permit Rules

• Permit Required: “A Building Permit is required to create an ADU or JADU. There are no exemptions.” (City of San Diego, Bulletin 400)
• 60-Day Approval Deadline: “If not approved or denied within 60 days, an ADU application is deemed approved.” (CA Gov. Code §65852.2)
• Permit Timeline: “City of San Diego ADU permits typically take ~3–5 months.” (City of San Diego – Permitting Timeline)

What’s Reviewed During Permitting

• Zoning compliance (setbacks, height, lot coverage)
• Building code safety (structure, fire safety, energy efficiency)
• Utility connections (water, sewer, electricity)
• Environmental or overlay zone requirements (e.g., Coastal Zone)

Permitting is key — submit complete plans upfront to shorten review times and prevent costly delays.

ADU Size, Height & Setbacks (Design Rules)

In San Diego, ADUs can range from 150 to 1,200 sq ft, may be up to 16 ft tall by right, and require 4 ft side and rear setbacks, with garage conversions allowed at 0 ft. (City of San Diego, Bulletin 400)

Every ADU in San Diego must meet basic size, height, and setback requirements. These zoning regulations give homeowners flexibility. They also keep neighborhoods compatible.

Key Design Rules

Size

• Minimum: 150 sq ft
• Maximum: 1,200 sq ft

Height

• Up to 16 ft by right
• Taller ADUs may be allowed if setbacks and zoning rules are met

Setbacks

• 4 ft required at side and rear property lines
• 0 ft allowed for garage conversions or interior conversions

How ADU Rules Shape Neighborhood Design

These rules make sure ADUs fit well in neighborhoods. They also give homeowners flexibility in design. For many, the 800 sq ft carve-out under state law provides enough space for a comfortable 1- or 2-bedroom unit even on smaller lots.

Plan with precision — knowing ADU size and setback rules upfront avoids redesign costs and streamlines city approval.

What Are The Parking Requirements for ADUs?

In San Diego, ADUs usually do not need new parking spaces if built near public transit. Even when parking is required, it cannot be more than one space per ADU or per bedroom.

Key Parking Rules

• No Parking Near Transit: “Local agencies shall not impose parking when the ADU is within ½ mile of public transit.” (CA Gov. Code §66322(a)(1))
• Maximum Cap: “Parking requirements for ADUs may not exceed one space per ADU or per bedroom, whichever is less.” (CA Gov. Code §66314(d)(10))
• Alternative Parking Options Allowed: If parking is required, spaces may be provided in tandem on a driveway or within a setback area, giving homeowners flexibility.

How Much Does It Cost to Build an ADU in San Diego?

Building an ADU in San Diego typically costs $375–$600+ per square foot, with total project budgets ranging from $200,000 to $450,000+, depending on size and finishes. Rising construction costs and city fees also play a role.

Key Takeaways

• Smaller ADUs (<750 sq ft): Save thousands in waived impact fees.
• Size drives cost: A 400 sq ft studio may cost $160k, while a 1,000 sq ft 2-bedroom can exceed $350k.
• Budget for soft costs: Permits, design, and utility connections can add tens of thousands.

San Diego ADU Cost Breakdown

How Long Does It Take to Build an ADU?

A full ADU project in San Diego usually takes 10–16 months from planning to completion, including design, permitting, and construction phases (ADU Pals).

Typical ADU Timeline

• Design & Pre-Planning: 1–2 months (research, budgeting, selecting plans)
• Permit Application & Review: 3–5 months (San Diego reviews ADU permits within 60 days, but resubmissions and corrections extend timelines)
• Construction: 4–8 months (site work, building, inspections)
• Final Approval & Move-In: 1 month (final inspections and certificate of occupancy)

Expected ADU Completion Timeframe

Even with California’s 60-day permit review law in place, it’s best to expect about a year or more before your ADU is ready for tenants or family use.

Expect 10–16 months — set realistic expectations for design, permitting, and build phases to avoid frustration.

Renting Out Your ADU (Rules You Must Know)

San Diego allows ADUs to be rented long-term (30+ days) but prohibits short-term rentals like Airbnb. State law also removed owner-occupancy requirements, so you don’t need to live on-site to rent out a standard ADU.

Key Rental Rules

• Short-Term Rentals Banned: “No. The San Diego Municipal Code prohibits using ADUs for short-term rental and will result in a Code violation.” (City of San Diego FAQ)
• No Owner-Occupancy Requirement: “Removes the 2025 sunset… and mandates no owner-occupancy requirement for ADUs.” (AB 976 – Gov. Code §66315)
• Junior ADUs (JADUs): Still require the property owner to live on-site in either the JADU or the main home.

Long-Term Rental Income From ADUs

ADUs are best used for long-term rentals. With average rents from about $1,900 to $3,600 per month, homeowners can earn significant passive income. They also add long-term value to their property. (AOAUSA – Market Update)

Rental Income Potential in San Diego (2023 Averages)

What Is a JADU (Junior ADU)?

A Junior Accessory Dwelling Unit (JADU) is a secondary unit of 500 sq ft or less, created within the walls of a single-family home. JADUs must have their own entrance and a small kitchen, but can share a bathroom with the main house.

Key Rules for JADUs

• Size Limit: No more than 500 sq ft (CA HCD ADU Handbook)
• Location: Must be built within the existing single-family home (including attached garages)
• Entry: Requires a separate exterior entrance
• Kitchen: Must include an independent or efficiency kitchen (CA Gov. Code §65852.22)
• Owner-Occupancy: The property owner must live on-site in either the JADU or the primary residence

Key Takeaway

JADUs are a excellent budget-friendly housing options if you want to add rental income or family space without building a separate structure. ADUs have stricter zoning regulations. One important rule is that the owner must live in the property.

ADU vs. JADU at a Glance

Financing & Incentives

San Diego homeowners can finance accessory dwelling units through local loan programs, fee waivers, and pre-approved design plans. The San Diego Housing Commission (SDHC) offers loans up to $250,000 with technical assistance at no cost.

Key Financing & Incentive Options

SDHC ADU Finance Program

• SDHC ADU Finance Program provides loans up to $250,000 and technical assistance at no cost.” (San Diego Housing Commission)
• Loan terms are 1% fixed construction loan and 4% fixed permanent loan

Impact Fee Waiver

• California law: “No impact fees for an ADU < 750 sq ft; above that, fees must be proportional.” (CA Gov. Code §66324)

Standard ADU Building Plans

• Pre-approved plans available from the City of San Diego to cut design costs and speed up permitting (City of San Diego Development Services)

Financing Options at a Glance

Next Steps for Your San Diego ADU Project

Building an accessory dwelling unit in San Diego is one of the smartest investments you can make as a homeowner. ADUs increase your property’s value. They generate reliable rental income. They also provide flexible living options for family or guests. With San Diego’s ADU-friendly laws and financing programs, there has never been a better time to start your project.

At Better Place Design & Build, we believe in more than just adding square footage — we believe in unlocking new potential with every square foot. Our mission is to create ADUs that are as functional as they are beautiful, tailored to your lifestyle, and designed to stand the test of time. We handle every step, from checking if an ADU is possible to getting permits, building, and finishing. This lets you focus on the exciting possibilities of your new space.

Why Homeowners Choose Better Place Design & Build

• One-Stop Shop: We manage everything — feasibility, design, permits, and construction — under one roof.
• Immersive Design: Step into your future ADU before it’s built with 3D modeling and virtual walkthroughs.
• Transparent Pricing: No hidden fees, just clear and fair pricing.
• Local Expertise: With over 20 years in San Diego, we know the codes, neighborhoods, and trends that shape successful projects.
• Proven Trust: Backed by 300+ glowing reviews and thousands of completed projects.

Let’s Build Your ADU Together

Whether you want a small rental, a modern guest house, or a home for multiple generations, we can help you make it happen.

Success starts with a plan — from financing to finishing, follow a clear roadmap to complete your ADU on time and on budget.