What is an ADU?
The term ADU stands for accessory dwelling unit. ADUs are accessory dwellings that share the lot of a primary dwelling.
So why are ADUs such a big deal these days? In 2017, the state of California passed legislation that made it easier for homeowners to build ADUs on their property. These laws were passed in order to help address the severe housing crisis we are currently experiencing in the state. The hope is that as more and more ADUs are built, more affordable housing can become available.

Benefits of ADUs
From generating passive rental income, to providing a private space for family and friends to stay in, there are plenty of benefits to ADUs.
1. Earn rental income
Wouldn’t you like to offset the cost of your mortgage on a monthly basis? Renting out a granny flat or ADU on your property is a great way to offset the high cost of home ownership here in California. With rental rates being at a premium in San Diego, ADUs are a smart way to earn both passive income in the short-term as well as gained property value in the long term.
2. Keep aging family close
As our family members age, such as our parents, we need to make some hard decisions. Can we trust that they will be safe living independently? With the ever-rising costs of nursing homes and assisted living communities, it can be a real challenge to ensure that our family members will be safe and taken care of.
An ADU allows you to have the flexibility to keep our aging parents close by, yet allow both them and you to still retain independence and privacy. When designing an ADU for a senior family member, it’s highly recommended to consider universal design.
What’s universal design?
Universal design consists of residential design standards to allow for the accommodation of handicap or disabled persons. Elements of universal design include ensuring that doorways are wide enough for a wheelchair or walker to easily go through. Another example includes ensuring that there are no raised thresholds on the floor, such as moldings or steps, which make it difficult for someone to maneuver over in a wheelchair or walker.
Universal design standards will help to create a safer place for your loved ones, and offer you peace of mind.
3. Provide extra space for guests
An ADU is also a great way to provide a separate space for friends and family members that visit. Are the in-laws coming into town for the holidays? What better than to offer them their own separate and independent unit? With Airbnb and hotel prices in San Diego being offered at a premium, it’s a cost-effective way to keep family and friends close-by.
4. Increase your property’s value
By turning your single-family home into a multifamily property, you are able to increase the value of your investment. With the addition of an income-generating unit, your property will become highly desirable when it comes time to sell.
Can I Build an ADU on my property in San Diego?
If you own a single-family home, then there is a high probability that you can build an ADU on your property. San Diego is one of the most ADU-friendly areas in California. The City of San Diego was actually one of the front runners to come out with ADU regulations. Furthermore, there are local municipalities throughout the area that offer beneficial exemptions for ADUs. For example, the City of San Diego has waived all development impact fees for ADUs saving homeowners tens of thousands of dollars.
Here are a few ADU-friendly municipalities in San Diego:
- City of San Diego
- County of San Diego
- La Mesa
- Poway
- Chula Vista
- Carlsbad
- Encinitas
- Vista
- San Marcos
How to Build an ADU in San Diego
There are several ways to go about adding an ADU to your property. It all depends on what your goals are for the unit, characteristics of your lot, and your budget.
Looking for an ADU-able property? Let’s talk.
Here are the three basic steps for building an ADU in San Diego:
Step 1) Design
Designing a unit that’s been customized to fit your property is a great way to go. When building a custom ADU, it’s important to work with a designer with ADU experience. They’ll know exactly how to design for small spaces, and will be in-tune with local ADU laws and regulations.
Step 2) Permit
Once you have a full set of plans, it’s time to submit them to the city building department for building permits. As of 2020, California state law mandated that local jurisdictions must act on ADU applications within 60 days. This change has helped to reduce one of the biggest bottlenecks when it comes to building ADUs, since city building departments used to have up to 120 days to process an application.
There may be changes that need to be made to your plans throughout the permit review process. Therefore, it is critical that you work with a designer who has experience and is able to implement changes quickly so that you can get your permits processed as soon as possible.
Step 3) Build
After you’ve received your building permits, it’s time to start construction. Again, it’s important to find a contractor with ADU experience. Since building an ADU can take 3-6 months, you’ll want to work with a team who is experienced, honest, knowledgeable, and communicative throughout the process.
To learn more, check out our guide on how to build an ADU in San Diego.
Types of ADUs
There are a few different types of ADUs that can be added to your property including:
- Garage Conversion
- Above garage
- Detached
- Prefabricated or Modular
- Attached
- Junior ADU(JADU)
The type of ADU you should go with will depend on your goals and any zoning requirements you’ll have to adhere to according to the city your property is located in. Garage conversions are one of the easiest ways to add an ADU to your property, since the structure already exists. Furthermore, new state laws have made it easier for homeowners to convert their garages to ADUs by offering exemptions including parking, solar, and more.To learn more, check out my guide on ADU garage conversions.
How Much Does it Cost to Build an ADU in San Diego?
The cost of your ADU will depend on a variety of factors such as:
- Design
- Size
- Permit Fees
- Type of ADU
As mentioned earlier, a garage conversion is oftentimes the most cost-effective route for an ADU. On the other hand, a newly-built detached ADU will be a bit more expensive. Therefore, your budget will be a main factor in determining the type of ADU that you go with.
Development Impact fees are one of the most costly types of permit fees. As of 2020, development impact fees for units below 750 sq ft have been waived throughout the state of California. This new law has helped homeowners save tens of thousands of dollars just on permit fees alone, making it a great time to build your ADU.
In San Diego, you can expect construction costs alone to fall around $200-$250 per square foot for newly-built, ground-up units. When evaluating the cost of your ADU, it’s important to remember that ADUs are much smaller than an average home. Therefore, the smaller the unit, the more expensive the per square footage price may seem. This is because within a smaller unit, there are no large living spaces to offset the costs of bathrooms and kitchens which are the most expensive areas in a living space.
Remember that one of the greatest benefits of ADUs is the ability to add value to your property. It’s a decision that will allow you to build wealth over time, and may be well worth the investment in the short-term.

What about Prefab ADUs?
Prefabricated ADU units are also a great way to add an ADU to your property. From modern to cottage style designs, there are a wide variety of prefabricated units available today.
One of the biggest advantages of prefab ADUs is that the construction of the unit occurs off-site at a manufacturing facility. This way, you don’t need to have a construction team actively working on your property for months, saving you time.
Not every property eligible for prefabricated ADUs, and there are a few factors to keep in mind. So it’s best to speak with a prefab ADU manufacturer to make sure it’s the right fit for your property.
San Diego Pre-Approved ADU Plans
To help bolster the growth of ADUs, both the county of San Diego and City of Encinitas have released pre-approved ADU plans that are permit-ready.
Sizes range from 600 sq ft to 1,200 sq ft, and come in a variety of distinct designs. If you’re interested in using one of these plans, it’s important to note that these plans are technically only “pre-approved” if your property falls within the jurisdiction of County of San Diego or the City of Encinitas.
To see if these templated plans are right for you, check out the links below:
What is a Junior ADU?
Junior ADUs are units that are contained entirely within the primary home and are converted from an existing bedroom. In many areas, there is the potential to have both an ADU and a JADU on the same lot.
Here are the requirements that a JADU must have:
- Separate entrance/exit
- Less than 500 sq ft
- Wet bar or kitchenette (not a full kitchen)
- Bathroom (may be shared with the main house)
- Deed Restriction
What is the deed restriction?
Although owner-occupancy requirements have been waived until 2025, this exemption only applies to ADUs – not JADUs. Therefore, the addition of a JADU will require owner occupancy on the property. Depending on your long-term goals, a JADU may or may not be the right fit.
For example, if your long-term goal is to house an aging parent in your home and you have a smaller budget to work with, a JADU may be the answer.
If your goal is to offer the ADU as a rental and also eventually rent out your primary home, a detached ADU or garage conversion may be your best option.

Looking for an ADU-able property to call yours?
As San Diego’s ADU Agent, I can help you locate the best property to help you achieve your ADU goals. From zoning requirements to assessing market conditions, there is a lot to consider when shopping for the perfect ADU-able property. Work with me and I’ll help take the guesswork out of your property search.
From first-time home buyers to veteran investors, it seems that everyone is on the hunt for best properties to invest in. With my experience in helping hundreds of homeowners navigate the ins-and-outs of ADUs throughout San Diego, I can help you find your next ADU-able property quickly and efficiently.
What are you waiting for?
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