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 9, 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

Aerial view of downtown San Antonio, Texas at night with rotating Tower of the Americas in foreground.

San Antonio and Austin are Fusing Into one Massive Megaregion

The region spanning the two central Texas cities is growing fast, posing challenges for local infrastructure and water supplies.

July 3, 2025 - Governing

White park shuttles with large Zion logo on side and red rock cliffs in background in Zion National Park.

Since Zion's Shuttles Went Electric “The Smog is Gone”

Visitors to Zion National Park can enjoy the canyon via the nation’s first fully electric park shuttle system.

July 15 - Reasons to Be Cheerful

Chart of federal transportation funding comparing Biden and Trump administration spending.

Trump Distributing DOT Safety Funds at 1/10 Rate of Biden

Funds for Safe Streets and other transportation safety and equity programs are being held up by administrative reviews and conflicts with the Trump administration’s priorities.

July 15 - Transportation for America

Close-up on yellow and black TAXI sign on top of beige car in central Munich, Germany.

German Cities Subsidize Taxis for Women Amid Wave of Violence

Free or low-cost taxi rides can help women navigate cities more safely, but critics say the programs don't address the root causes of violence against women.

July 15 - Bloomberg