Simple Homeowner's Guide to San Diego Granny Flats

Simple Homeowner's Guide to San Diego Granny Flats featured image

September 11, 2018 / by Gregg Cantor / In In-law Suites

Since 2016, approved accessory dwelling units have increased 63 percent throughout California. With the loosened regulations and simplified permitting process that has trickled down to San Diego, you have the opportunity to maximize your property. Whether residents build in-law suites in San Diego or rental units onto their homes, it’s important to know the ADU rules and regulations before starting this popular construction project.

A Closer Look at ADUs

What is an ADU? It’s an accessory dwelling unit that’s often referred to as a “granny flat.” These are living spaces that are attached to a qualifying residential property. There are three types of units:

  • Detached
  • Attached
  • Repurposed existing

illustration of main ADU types

Detached units are standalone structures that are separated from the primary residence. An attached unit is built onto an existing residence and has its own private entrance, bath and kitchen. Above the garage, attics and basements fall under this category. An example of a repurposed existing unit is a garage conversion. This is a space within the primary house that’s converted into a unit for independent living.

Five Major ADU Changes

The City of San Diego made five significant changes that impact homeowners seeking to construct granny flats. These recent updates include:

  1. New Resources - City officials provide pre-approved ADU flat designs and instruction manuals to speed up construction.

  2. Wide-Ranging Fees - Location and granny flat type impacts fee costs. The fees range from $4,800 to over $80,000. The City of San Diego passed a waiver of development and impact fees, which saves local residents $17,000 on average.

  3. Fee Waivers - Encinitas homeowners who are building in-law suites up to 1,200 square feet can save approximately $3,500 in waived fees.

  4. Expanded ADU Size - In-law suites may be 1,200 square feet or 50% of the primary home’s size, whichever is less. This is up from 700 square feet. For example, if an existing house is 3,000 square feet, the attachment it can’t exceed 1,200 square feet in size.

  5. No Vacation Rentals - ADU rentals must have a minimum 30-day lease, which eliminates the granny flats from being used as short-term vacation rentals.

Property Qualifications

An ADU can be built on property that is zoned for a single-family residence. In some instances, granny flats may be built on some multi-family lots. It’s best to check with the City before building on the land. Additionally, to obtain a permit for a lot, it must be free of code violations. Here are a few additional facts worth noting:

  • San Diego ADUs are always rentable, but these units can’t be sold separately from the primary home.
  • ADUs only require a fire sprinkler system when it’s required for the main residence.
  • Owner-occupancy isn’t necessary for renting either primary homes or ADUs, unless you live in San Diego County.
  • Existing structures converted to CUs aren’t subject to water or sewer charges when it has the correct meter size.


Every structure must maintain a specific distance from a property line, curb or structure within a building. This is done for the purposes of environmental protection, privacy and public safety. The City requires that each ADU unit complies with the main property’s setback. In the case of a two-story granny flat, it must be situated five feet from the rear and side lot lines. However, existing permitted garages are exempt from this requirement.


Parking accommodations is another matter you must factor into your construction. The City requires that newly built granny flats provide .5 space for each bedroom whether it’s an area in the driveway or tandem parking. With a converted garage, you can have parking spots anywhere on the property. Additionally, the spaces must measure at 8.5 feet by 18 feet. There aren’t any parking requirements for the following if you:

  • Reside within one block of a car share location
  • Live in a historic district
  • Build the ADU unit onto an existing main residence
  • Live a mile away from public transportation

San Diego granny flats are a hot trend that many homeowners are taking advantage of. Changes in the ADU rules and regulations make maximizing your property an easier and faster process. If you need a trusted company for your ADU construction project, contact Murray Lampert Design, Build, Remodel. We’re ready to put our 40 plus years of experience to work for you.

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