Accessory Dwelling Units (ADUs) have become one of California’s most popular ways to add living space, create rental opportunities, or increase a property’s flexibility. Thanks to recent state legislation, many homeowners have more opportunities than ever to build an ADU.
If you own a home in Coastal San Diego, however, there may be additional considerations beyond California’s statewide ADU laws. Depending on where your property is located, local zoning, Coastal Development Permit requirements, and city specific regulations can all affect your project.
What Is an ADU?
An Accessory Dwelling Unit is a secondary residential unit located on the same lot as an existing or proposed primary home. Depending on the property, an ADU may be:
- A detached backyard cottage
- An addition connected to the primary residence
- A converted garage
- A converted portion of the existing home
- A newly constructed unit above a garage
California has passed several laws over the past few years to encourage ADU construction as one way to help address the state’s housing shortage. While state law establishes many of the baseline standards, local jurisdictions still administer permits and development requirements.
Types of ADUs and Common Configurations
ADUs can take several different forms depending on the property layout, available space, and local development requirements. Common types include:
- Detached ADU: A separate structure located on the same lot as the primary residence, such as a backyard cottage.
- Attached ADU: A unit connected to the existing home, such as an addition with its own living facilities.
- Interior Conversion: A portion of an existing home converted into an independent living space.
Garage Conversion: A garage transformed into a residential unit. - Above-Garage ADU: A second-story unit built above an existing or new garage structure.
A Junior Accessory Dwelling Unit (JADU) is another option available to some homeowners. Unlike a traditional ADU, a JADU must be completely contained within an existing or proposed single-family residence and can be up to 500 square feet.
Why ADUs Are Becoming More Popular in Coastal San Diego
For many homeowners, an ADU provides additional flexibility without purchasing another property.
Common reasons buyers and homeowners choose to build an ADU include:
- Housing aging relatives or caregivers
- Creating space for adult children
- Generating long term rental income
- Providing a guest house
- Creating a dedicated home office or studio
- Increasing overall property utility
With limited available land in many coastal communities, ADUs have also become part of California’s broader effort to expand housing opportunities while making use of existing residential lots.
Can You Build an ADU in Coastal San Diego?
In many cases, yes.
California law generally allows ADUs on residential properties that meet certain requirements, but approval depends on more than state law alone.
Before designing an ADU, you’ll want to consider:
- Your property’s zoning
- Whether your property is inside the California Coastal Zone
- Local development standards
- Historic district regulations
- Environmental constraints
- Existing structures on the property
Because Coastal San Diego includes several different cities and jurisdictions, requirements can vary depending on where the property is located.
San Diego Coastal Zones Map
Interactive map · SANDAG GEOHUB
How the California Coastal Act Can Affect Your ADU Project
One of the most common questions homeowners ask is whether living near the coast changes the permitting process.
The answer is: sometimes.
Many coastal neighborhoods are located within California’s Coastal Zone. If your property falls within this area, additional regulations may apply.
The California Coastal Act is intended to balance responsible development with protecting coastal resources, public access, and environmentally sensitive areas. It does not prohibit ADUs, but it may affect how your project is reviewed.
Depending on your property’s location, you may need additional approvals such as a Coastal Development Permit before construction can begin.
Some factors that may influence your project include:
- Coastal Overlay Zone requirements
- Public coastal access
- Bluff or shoreline hazards
- Environmentally sensitive habitat areas
- Local Coastal Program regulations
For a deeper look at coastal permitting and development regulations, read our guide to Coastal Commission Rules for San Diego properties here.
Which Coastal Communities Have Different ADU Requirements?
Although California establishes many of the statewide rules, local governments administer permits and development standards.
Here’s where homeowners typically begin their research.
| Community | ADUs Allowed? | Coastal Permit May Apply? | Primary Planning Department |
|---|---|---|---|
| La Jolla | Yes | Often | City of San Diego |
| Pacific Beach | Yes | Often | City of San Diego |
| Point Loma | Yes | Often | City of San Diego |
| Ocean Beach | Yes | Often | City of San Diego |
| Coronado | Yes | Sometimes | City of Coronado |
| Del Mar | Yes | Often | City of Del Mar |
| Solana Beach | Yes | Often | City of Solana Beach |
| Encinitas | Yes | Often | City of Encinitas |
What Makes Building Near the Coast Different?
Building near the coast often comes with additional considerations that buyers and homeowners may not encounter elsewhere in San Diego County.
Some examples include:
| Coastal Consideration | Why It Matters |
|---|---|
| Coastal Development Permits | May require additional review |
| Salt Air | Can influence material selection |
| Bluff Setbacks | May affect where an ADU can be located |
| Flood Zones | May influence insurance and design |
| Small Lot Sizes | Can affect placement options |
What Should You Consider Before Building an ADU in San Diego?
Every property is different, but homeowners should think about more than just available space.
Important considerations include:
- Construction budget
- Utility connections
- Site access
- Parking requirements
- Coastal permitting
- Lot coverage
- Construction timeline
- Long term maintenance
Before hiring an architect or contractor, it’s worth confirming a few details about your property. Start by checking:
- Your property’s zoning
- Utility and infrastructure requirements
- Utility and infrastructure requirements
- Your city’s ADU regulations
- Coastal or environmental approvals
- Required permit applications
- Any HOA restrictions, if applicable
It’s also important to note that ADU size limits depend on the type of unit and local regulations.
In general:
- Attached ADUs: May be up to 50% of the primary residence size, with a maximum size of 1,200 square feet in many cases.
- Detached ADUs: May be built up to 1,200 sq. ft. regardless of the size of the primary residence.
Because lot size, setbacks, zoning, and coastal requirements can influence what is possible, homeowners should confirm specific requirements for their property before beginning design plans. Understanding these requirements can help buyers and sellers avoid unexpected delays during a transaction.
Recent ADU Updates San Diego Homeowners Should Know
Recent changes include:
- AB 2533: May provide a pathway for certain unpermitted ADUs built before January 1, 2020 to pursue legalization if they meet health and safety standards.
- AB 1033: Allows local jurisdictions to create programs that may enable the separate sale of ADUs through a condominium conversion process.
ADUs continue to play an important role in expanding housing opportunities throughout California, and many Coastal San Diego homeowners are exploring whether they make sense for their property.
Because regulations can differ between cities and coastal neighborhoods, taking time to understand local requirements before beginning the design process can help avoid delays later. Whether your goal is creating additional living space, increasing property flexibility, or generating rental income, knowing which rules apply to your property is the first step toward a successful project.
