More Cities Legalizing 'Granny Flats'

Accessory Dwelling Units continue to gain steam as one approach for increasing affordability, but experts caution that housing affordability requires broader solutions.

2 minute read

January 15, 2021, 6:00 AM PST

By Diana Ionescu @aworkoffiction


Residential Development

Rungtiwa P / Shutterstock

Cities and states across the country are realizing the potential of legalized Accessory Dwelling Units (ADUs) as an inexpensive way to increase density and available housing units without drastically changing a neighborhood's character. According to Kol Peterson, author of Backdoor Revolution: The Definitive Guide to ADU Development, "there has been a dramatic uptick in ADU regulatory relaxation over the last few years." In a piece for the Washington Post, Haisten Willis assesses the benefits of ADU construction, which is experiencing a resurgence, particularly in high-cost, low-density neighborhoods on the West Coast.

California and Oregon have passed statewide legislation legalizing ADUs, and Chicago is implementing a pilot program to test the concept. Between 2016 and 2019, ADU permits in California jumped from 1,269 to 14,702, signaling a pent-up demand for "granny flats." Los Angeles, which issued 80 ADU permits in 2016, issued 6,747 in 2019.

The ADU can be an ideal housing type for seniors who want to live near their family and provides an unobtrusive way to increase available units, but advocates admit that "the devil is in the details" and more oversight is required to ensure ADU landlords can navigate the process and maintain adequate living conditions. "It still doesn’t absolve the city from the protections they need to keep for renters," says organizer Ebonée Green. Homeowners who want to build ADUs don't always know how to manage contractors or get permits, and banks, unfamiliar with the construction type, have so far been reluctant to issue loans for ADU projects.

While the growth in ADU construction is encouraging, experts warn that legalizing ADUs is only "a small tool in the box," not a broad solution to housing affordability issues.

Thursday, January 7, 2021 in The Washington Post

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Cover CM Credits, Earn Certificates, Push Your Career Forward

Aerial view of town of Wailuku in Maui, Hawaii with mountains in background against cloudy sunset sky.

Maui's Vacation Rental Debate Turns Ugly

Verbal attacks, misinformation campaigns and fistfights plague a high-stakes debate to convert thousands of vacation rentals into long-term housing.

July 1, 2025 - Honolulu Civil Beat

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

July 9, 2025 - Diana Ionescu

Map of Haussmann's redesign of Paris in the 1850s through 1870s under Napoleon III.

In Urban Planning, AI Prompting Could be the New Design Thinking

Creativity has long been key to great urban design. What if we see AI as our new creative partner?

June 30, 2025 - Tom Sanchez

View of dense apartment buildings on Seattle waterfront with high-rise buildings in background.

King County Supportive Housing Program Offers Hope for Unhoused Residents

The county is taking a ‘Housing First’ approach that prioritizes getting people into housing, then offering wraparound supportive services.

2 hours ago - Real Change

Aerial view of suburban housing near Las Vegas, Nevada.

Researchers Use AI to Get Clearer Picture of US Housing

Analysts are using artificial intelligence to supercharge their research by allowing them to comb through data faster. Though these AI tools can be error prone, they save time and housing researchers are optimistic about the future.

3 hours ago - Shelterforce Magazine

Green bike share bikes parked in a row on a commercial street with outdoor dining and greenery.

Making Shared Micromobility More Inclusive

Cities and shared mobility system operators can do more to include people with disabilities in planning and operations, per a new report.

4 hours ago - Cities Today