California Sees Spike in ADU Permits

Homeowners in the state are eagerly taking advantage of new laws allowing them to build additional housing units, making a small but significant impact on the housing supply.

2 minute read

May 29, 2023, 7:00 AM PDT

By Diana Ionescu @aworkoffiction


Small grey accessory dwelling unit cottage in California backyard

City of Salinas / Accessory dwelling unit

The liberalization of laws surrounding the construction of accessory dwelling units (ADUs), also known as granny flats, is starting to make a significant dent in California’s housing crisis. While far from a panacea, the flurry of permits issued for ADUs signal that homeowners across the state are eager to take advantage of the opportunity to build an extra housing unit on their property.

As Erica Werner explains in The Washington Post, “More than 23,000 ADU permits were issued in California last year, compared with fewer than 5,000 in 2017 — which was around when ADU permitting began to take off thanks to legislative and regulatory changes in the state.” Los Angeles issued 7,160 of those permits, while only issuing 1,387 permits for single-family homes in the same time period.

Despite the high cost of ADU construction—the average unit runs roughly $300,000—“a study from the NYU Furman Center found that ADUs are being built not in the wealthiest neighborhoods, but more often in low- to middle-income areas, and often in places with relatively good access to jobs.” According to study author Christopher Elmendorf, “‘That’s consistent with the theory that this is a viable form of development in places that you may not’ otherwise be able to easily build.” David Garcia, policy director for the Terner Center for Housing Innovation at the University of California at Berkeley, says the speed at which Californians are applying for ADU permits signals “a pent-up demand from homeowners to want to do more with their land.”

Sunday, May 21, 2023 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

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 16, 2025 - Diana Ionescu

Green vintage Chicago streetcar from the 1940s parked at the Illinois Railroad Museum in 1988.

Chicago’s Ghost Rails

Just beneath the surface of the modern city lie the remnants of its expansive early 20th-century streetcar system.

July 13, 2025 - WTTV

Blue tarps covering tents set up by unhoused people along chain link fence on concrete sidewalk.

Study: Anti-Homelessness Laws Don’t Work

Research shows that punitive measures that criminalized unhoused people don’t help reduce homelessness.

July 6, 2025 - Next City

Tunnel for pedestrians, bikes, and buses in Lyon, France lit up with purple lights.

The French Solution to Congested Tunnels: Make Them Car-Free

Bay Area transportation officials keep expanding car capacity. Lyon’s Croix Rousse Tunnel offers a different way.

4 hours ago - Streetsblog San Francisco

Missouri state Rep. Chris Brown speaking in government chamber.

Missouri Governor Reverses Anti-Discrimination Housing Policies

A new state law bars cities from prohibiting source-of-income discrimination against tenants using Section 8 housing vouchers.

5 hours ago - Missouri Independent

Pedestrians crossing a rainbow painted crosswalk in New York City.

USDOT Launches Unfunded 'SAFE ROADS' Program

The program targets “distractions” and “political messages or artwork,” and paves the way for autonomous vehicles.

5 hours ago - Urban Milwaukee