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

Red and white "Wildfire Evacuation Route" sign on signpost.

Cal Fire Chatbot Fails to Answer Basic Questions

An AI chatbot designed to provide information about wildfires can’t answer questions about evacuation orders, among other problems.

July 10 - The Markup

Protester at Echo Park Lake, Los Angeles holding sign that says "Housing is a human right"

What Happens if Trump Kills Section 8?

The Trump admin aims to slash federal rental aid by nearly half and shift distribution to states. Experts warn this could spike homelessness and destabilize communities nationwide.

July 10 - Shelterforce Magazine

Aerial of rainbow painted crosswalks at large intersection in Castro District, Sna Francisco, California.

Sean Duffy Targets Rainbow Crosswalks in Road Safety Efforts

Despite evidence that colorful crosswalks actually improve intersection safety — and the lack of almost any crosswalks at all on the nation’s most dangerous arterial roads — U.S. Transportation Secretary Duffy is calling on states to remove them.

July 10 - Streetsblog USA

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.

Home and Land Services Coordinator

Appalachian Highlands Housing Partners

Associate/Senior Planner

Gallatin County Department of Planning & Community Development

Senior Planner

Heyer Gruel & Associates PA