Think of a granny flat as a mini apartment built on an existing property. It has its own entrance, kitchen, bathroom and living space.

Known by a variety of names that differ by region, granny flats are modest “accessory dwelling units” ranging in size from 250-1200 square feet. These mini homes can take many forms, attached or detached, but must exist on a single family property and have their own entrance, kitchen, bathroom and living space.

While granny flats can be stand alone homes, they are most often constructed by converting a space that once was a garage, basement or attic.

Structural Forms of a Granny Flat

what is an accessory dwelling unit

What name are you familiar with?

  • Accessory Dwelling Unit (ADU): The technical, architectural term used by a city or permitting office.
  • In-Law Suite
  • Backyard Cottage
  • Mother in-law Suite
  • Laneway House
  • Secondary Unit
  • Basement Apartment

Granny Flats Provide Flexibility & Affordable Housing

Although many people buy and live in their home for many decades, their needs change over time. Granny flats can complement your lifestyle while also providing solutions to life’s challenges.

For example, a young family may use the space for rental income. As the family grows perhaps a college bound teen saves money by living in the granny flat. Later in life parents might explore downsizing and renting out the main house for more financial freedom.

what is an accessory dwelling unit


What’s Great About Granny Flats?

According to Maxable’s 2018 survey exploring the reasons for granny flat development:

Monthly rental income and caring for an elderly family member are the top two reasons people choose to build a granny flat.

There are a lot of awesome reasons why someone might explore this project. Other noteworthy survey answers include:

  1. Stay in a beloved neighborhood
  2. Provide affordable housing to others
  3. Higher profits for local businesses through increased neighborhood density
  4. Flexibility of the space
  5. Help pay mortgage
  6. Fight gentrification
  7. Extra space for home busineses
  8. Save to afford buying a house
  9. Friends and relatives visit comfortably
  10. Affinity for tiny spaces, live minimally
  11. Garage not being well utilized and desire to get rid of extra junk

In fact, there are a lot of reasons cities stand to benefit as well. Affordable housing, and lack thereof, is at the top of the list. Cities like, San Francisco, San Diego, Los Angeles, Portland, Seattle, and Austin struggle with soaring housing prices and lack of availability.

Yet, these cities are reluctant about allowing new development projects begin. Moreover, until recently, many of these cities had extremely restrictive building codes in place. Local municipalities boasted huge impact fees, or massive minimum lot size requirements aimed at discouraging people from building accessory dwelling units.

While Granny flats won’t solve California’s housing crisis, they can help. According to 2018 reports, San Diego, a city of 1.4 million, is expected to grow by one million people by 2050.

Why are you interested in an accessory dwelling unit? Leave a comment below! We want to hear from you.

What Is a Granny Flat?