Building a Granny Flat in San Diego County – What You Need to Know

At Specialty Home Improvement, we’ve been building Accessory Dwelling Units (ADUs) — or “granny flats” — for our clients for years. For most of those years, getting a permit to build a granny flat involved jumping through multiple hoops and complying with very restrictive requirements. To address the severe housing shortage we face, the State of California recently passed legislative reforms making these types of additions easier than ever to build.

Granny Flats Basics

What is a Granny Flat? More formally known as an Accessory Dwelling Unit or ADU, a granny flat provides complete independent living facilities for one or more people. They may sometimes be referred to by other names as well, including: companion unit, casita, in-law unit, secondary unit or even a room addition.

What are the types of ADUs? There are three primary types of ADUs:

  • Attached ADU. A new space such as a 2nd story or suite addition is added onto an existing primary structure as an independent living unit
  • Detached ADU. A new independent structure is built on the property as a freestanding independent living unit
  • Re-purposed ADU. Existing living space such as a garage or loft within the primary dwelling is renovated into an independent living unit

Why build an ADU? Most homeowners build an ADU for one of three reasons:

  • Rental income. Helping pay the mortgage or as a second stream of income
  • Housing for relatives. Adult children, parents, in-laws or relatives with special needs who still have a desire for privacy
  • Downsizing. Some of our recent clients now rent out the main home while they have downsized and live in the ADU

Building a Granny Flat in San Diego

As those of us who call San Diego County home know, our region is comprised of many small municipalities, most with their own rules and guidelines regarding just about everything. When it comes to granny flats or ADUs, they’re no exception.

The good news, however, is that the State of California has mandated that local ordinances encourage the building of ADUs by reducing barriers and streamlining approvals. In essence, this means that any local ordinance adopted prior to January 1, 2017 that is not in compliance with the changes to ADU law will be null and void. Until an ordinance that complies is adopted, local governments must apply “state standards”.

Simply, in the absence of a local ordinance complying with ADU law, local review must be limited to “state standards” and cannot include additional requirements such as those in an existing ordinance. Additionally, new ordinances may not unreasonably restrict the ability of the homeowners to create ADUs.

Here’s what you need to know, keeping in mind that regulations and requirements may change slightly depending on your local municipality:

  • Location. ADUs must be built on the same residential lot as the primary residence and must be independent from the residence with no interior access. They cannot be sold separately.
  • Facilities. An ADU must be an independent living unit with sleeping, bathing and kitchen facilities.
  • Parking. If located within ½ mile from public transit (such as a bus stop), no additional parking is required for an ADU. Otherwise, one additional off-street parking space is required (uncovered, such as tandem parking in a driveway).
  • Size. An ADU may be up to 50% of the square footage of the primary residence or a maximum of 1,200 s.f.
  • Rental. An ADU may not be rented for less than a 30 consecutive day period
  • Setbacks. ADUs must comply with the main residence setbacks.
  • Fire sprinklers. Fire sprinklers are only required in an ADU if they are required in the main residence.

If you have any questions about building an ADU or granny flat in San Diego or one of our beautiful municipalities that aren’t answered here, give us a call. Specialty Home Improvement is a design-build contractor and Certified Aging-In-Place Specialist that specializes in building ADUs.

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