California has passed a series of landmark laws over the past several years that make building an ADU significantly easier than it used to be. Cities and counties have lost much of their ability to block ADUs. Here's what you need to know.

The Big Picture: What Changed

Before 2017, local governments had enormous power to block or delay ADUs through excessive fees, parking requirements, design standards, and slow permit processing. A series of state laws (AB 68, SB 13, AB 670, AB 881, SB 897, AB 2221) systematically dismantled these barriers. Today, if you meet basic requirements, your city generally cannot say no.

What Cities CANNOT Do

  • Require more than one parking space per ADU (and none if within half a mile of transit)
  • Require owner-occupancy of the primary residence (as of 2020)
  • Require setbacks greater than 4 feet from rear and side property lines for detached ADUs
  • Charge impact fees on ADUs under 750 sq ft
  • Take longer than 60 days to approve or deny a complete ADU application
  • Deny an ADU based on aesthetic objections alone (within state standards)

By-Right Approval

This is the most important concept for homeowners. An ADU that meets state and local standards is entitled to "by-right" approval — meaning the city must approve it without discretionary review (no planning commission hearings, no neighbor notifications, no design review board).

This dramatically reduces the time, cost, and uncertainty of the permit process.

Key Requirements You Must Meet

Standard Requirements (may vary by jurisdiction)

• Detached ADU: max 1,200 sq ft (or 50% of primary home, whichever is less in some jurisdictions)
• Minimum setbacks: 4 feet rear and sides
• Height: up to 16–25 feet depending on zone
• Fire sprinklers: required if primary home requires them
• Separate entrance required

The JADU Option

Junior ADUs (JADUs) are a special category created specifically to make it easier to convert existing space. Key rules:

  • Maximum 500 sq ft
  • Must be within or attached to the primary residence
  • Can share a bathroom with the primary residence
  • Requires a kitchenette (not a full kitchen)
  • No separate permit fees for interior conversions

What About HOAs?

Under AB 670 (2019), HOA CC&Rs cannot prohibit ADUs outright. An HOA can impose "reasonable restrictions" on design and placement, but cannot effectively prevent you from building.

SB 9: The Duplex Law

SB 9 (2022) allows homeowners to split their lot and build a duplex on each parcel in most single-family zones. Combined with ADU rights, this means a single-family lot could potentially accommodate 4 units. This is significant for real estate investors.

"California has done more in the last 5 years to facilitate ADU construction than it did in the previous 50. If you've been waiting to build — the regulatory environment has never been more favorable."

Want to understand what these laws mean for your specific property? Schedule a free consultation — we'll walk you through your options.