San Diego Accessory Dwelling Unit (ADU)
In response to San Diego’s housing shortage, accessory dwelling units (ADUs) have become more popular than ever. In recent years, the city has done a lot to make it easier and cheaper to build ADUs. They are a great way to offset the cost of your home, take advantage of the high cost of rent in San Diego County, or give yourself a little more privacy if you have a multigenerational home.
What is an ADU?
For San Diego County zoning purposes, accessory dwelling units (ADU) are a secondary, self-contained living area built on the property of a single-family home. An ADU can be attached to the main house, detached, or converted from an existing structure like a garage.
Sometimes they are also called casitas, granny flats, backyard cottages, guest houses, mother-in-law units, pool houses, in-law apartments, bonus units, accessory apartments, or secondary living units. They are often used by grandparents, young adult children, nannies, houseguests, and renters.
They usually have a kitchenette, bathroom, and private entrance. Depending on the size and design, they may be all one room like a studio apartment. Or they can have a bedroom and separate living area.
Design Options
San Diego homeowners have several ADU styles to choose from, each with unique benefits:
Detached ADU – A standalone unit separate from the main house, offering complete privacy.
Attached ADU – Connected to the main home, sharing one or more walls but with a private entrance.
Garage Conversion ADU – Transform an existing garage into a livable space without expanding your property’s footprint.
Junior ADU (JADU) – A smaller unit (up to 500 sq. ft.) within the main home, often utilizing an existing bedroom or garage.
How Much Does it Cost to Build an ADU in San Diego?
An ADU is a great investment in your home, but you will want to make sure you are well aware of the costs. Even for a small space, you will need to add electrical, plumbing, and heating. Plus, you will need to budget for a bathroom and kitchenette.
That is why building an ADU can cost $300 to $600 a square foot depending on the degree of difficulty, where the build out is going, and whether or not it is two-story. This does not include permit fees.
If an elderly family member will be using the ADU, you will want to make sure the secondary living unit is accessible to seniors. TR Construction also specializes in aging in place remodeling and can help bring the unit in line with universal design or accessible design (ADA) principles.
What are San Diego County’s Zoning Laws for ADUs?
Recent changes in California state law have made it much easier to build an ADU. You will still require a building permit, but the fees have been dramatically lowered and the approval process is now much easier. However, the ADU cannot be used as a vacation rental. To prevent the building of vacation rentals, any leases for ADUs cannot be for less than 30 days.
For more information about San Diego County and surrounding cities guidelines
- Accessory Dwelling Unit/Junior Accessory Dwelling Unit
- San Diego Planning and Development Services: ADU Information
- Accessory Dwelling Unit/Junior Accessory Dwelling Unit
San Diego ADU Builders
TR Construction has been working in San Diego County since 1994. We are very familiar with the zoning laws and can help guide you in the process of building your own ADU. If you would like more details about granny flats and the required steps for building one in San Diego, please give us a call at (858) 537-6490.
