Key ADU Law Changes to Expect in 2026 for San Diego and Southern California
- lauren0408
- Dec 16, 2025
- 4 min read
Accessory Dwelling Units (ADUs) have become a popular solution for San Diego homeowners and residents across Southern California looking to add affordable living space, generate passive income, or create a comfortable mother in law suite. As 2026 approaches, new ADU laws will reshape how people wanting to build an ADU plan their projects. Understanding these changes is essential for anyone considering a custom ADU, whether for a college rental, a retired family member, or as a real estate investment.
What Are ADUs and Why Are They Important?
ADUs are small, secondary housing units built on the same lot as a single-family home. They can take many forms, including detached units, converted garages, or basement apartments. For many San Diego homeowners, ADUs provide a way to increase property value and create affordable housing options in a city where housing costs continue to rise.
People wanting to build an ADU often seek to:
Create a private living space for retired family members or adult children
Generate steady income through college rentals or long-term tenants
Add a mother in law suite for multigenerational living
Invest in real estate without buying additional property
With the demand for affordable homes growing, ADUs offer a practical solution for expanding housing supply without large-scale development.
Key ADU Law Changes Coming in 2026
The state of California and local governments like San Diego have been updating ADU regulations to encourage more construction while addressing concerns about neighborhood character and infrastructure. Here are the most important changes to expect in 2026:
1. Increased Size Limits for ADUs
Currently, many ADUs are limited to 800 square feet or less. Starting in 2026, San Diego will allow larger ADUs in many cases, with some units permitted up to 1,200 square feet. This change benefits people wanting to build an ADU that can comfortably house a family member or serve as a full rental unit.
Larger ADUs mean more flexibility for:
Designing a custom ADU with multiple bedrooms
Adding full kitchens and living areas
Creating accessible spaces for retired residents or those with mobility needs
2. Relaxed Parking Requirements
Parking has been a major hurdle for ADU builders. Many neighborhoods require one or more off-street parking spaces for each new unit, which can be costly or impossible on small lots. The new laws will reduce or eliminate parking requirements for ADUs located near public transit or in urban areas like central San Diego.
This change opens opportunities for:
More people wanting to build an ADU without the expense of adding parking
Increased use of ADUs as affordable homes near transit hubs
Easier approval processes for builders and project managers
3. Streamlined Approval Process
San Diego plans to speed up ADU permitting by simplifying application steps and reducing fees. Builders and general contractors will benefit from clearer guidelines and faster turnaround times. This means people wanting to build an ADU can start construction sooner and avoid costly delays.
Streamlining includes:
Online application submissions
Reduced plan check times
Lower permit fees for smaller ADUs
4. Expanded Use of Junior ADUs (JADUs)
Junior ADUs are smaller units, typically under 500 square feet, created by converting part of an existing home. The 2026 laws will make it easier to build JADUs alongside standard ADUs, allowing homeowners to add two separate rental units on one property.
This is ideal for:
San Diego homeowners looking to maximize rental income
Families needing flexible living arrangements for retired parents or college students
Increasing affordable housing options without major construction
How These Changes Affect Different Groups
Retired Residents and Multigenerational Families
For retired individuals or families wanting to care for aging parents, the larger size limits and easier approvals mean they can build comfortable mother in law suites or custom ADUs tailored to specific needs. These units provide privacy while keeping loved ones close.
People Wanting to Build an ADU for Income
Whether renting to college students or long-term tenants, the new laws make ADUs a stronger real estate investment. Reduced parking requirements and faster permits lower upfront costs. Larger units can command higher rents, increasing passive income potential.
Builders, General Contractors, and Project Managers
Professionals involved in ADU construction will see benefits from clearer rules and streamlined processes. This allows them to manage projects more efficiently and deliver better results for clients. Builders can also advise homeowners on the best ADU options under the new regulations.
Practical Tips for San Diego Homeowners Planning an ADU in 2026
If you are a San Diego homeowner or someone wanting to build an ADU, here are some steps to prepare for the upcoming law changes:
Consult with a builder or general contractor early to understand new size and parking rules.
Consider a custom ADU design that fits your family’s needs or rental goals.
Explore options for junior ADUs if you want to maximize rental income.
Check proximity to public transit to take advantage of reduced parking requirements.
Plan your budget with faster permit approvals in mind to reduce holding costs.
Work with a project manager to keep your ADU construction on schedule and compliant with new laws.
The Future of ADUs in Southern California
The 2026 ADU law changes reflect a growing recognition that these units are a key part of solving housing challenges in San Diego and beyond. By making it easier and more affordable to build ADUs, the city supports homeowners who want to create affordable homes, generate income, or provide living space for family.
For retired residents, people wanting to build an ADU, and investors, these changes open new doors. ADUs will continue to be a smart real estate investment and a practical way to add value to your property.
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