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California Signs AB 956 and SB 1116: the Nation's Largest ADU Expansion Clears the Governor's Desk

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California Signs AB 956 and SB 1116: the Nation's Largest ADU Expansion Clears the Governor's Desk

Governor Gavin Newsom signed AB 956 (Quirk-Silva — accessory dwelling units and junior ADUs) and SB 1116 (Caballero — planning and zoning: housing development projects: subdivisions) on September 29, 2026, just inside the September 30 signing deadline, alongside a broad housing package: SB 1117 (Cervantes — a second ADU bill), AB 1621 (Wilson — post-entitlement phase permits under the Housing Accountability Act), AB 1751 (Quirk-Silva — the "Missing Middle Townhome Ownership Act," a streamlined approval pathway for qualifying townhome developments), AB 1815 (Wicks — statewide factory-built housing standards), SB 328 (Grayson — CEQA exemption for surplus land, unlocking the former Concord Naval Weapons Station's planned 10,000 homes, 25% affordable) and SB 344 (Weber Pierson — streamlining CEQA review for the San Diego Sports Arena site's 4,250 homes). All take effect January 1, 2027.

This resolves the biggest state-policy question this topic had been tracking since the AEI Housing Center's September 10 scorecard (seven states enacted, California pending): AB 956's ministerial approval of up to two detached ADUs per single-family lot was estimated by AEI at ~96,000 homes/year — the single largest pending bill in the country.1 Signature makes California the eighth Playbook-aligned state and roughly doubles the enacted supply-impact estimate (72,609 → ~169,000 homes/yr).

Newsom's message framed the package as permitting reform: "Every Californian deserves a fair shot at a stable home – families shouldn't have to wait years for housing to be approved and built in their communities. That means continuing to push forward with smart, practical solutions that open more doors for families and strengthen communities across our state." The governor's office says streamlining laws since 2019 cut average application-to-entitlement time 57% (160 → 68 days in 2024), and that jurisdictions have planned to accommodate at least 3.6 million new homes, including 1.4 million affordable.

For builders, the operationally interesting pieces are AB 1621 (limiting repeated plan-check reviews and tightening appeal timelines — "Strengthening deadlines and enforcement for housing permits") and AB 1751's townhome ownership pathway; for the ADU finance ecosystem, AB 956 plus SB 1117 together govern how a California ADU project works from January 1, 2027.

Still open on the policy docket: Massachusetts Question 7 (Nov 3 ballot — the first ballot-box test of lot-size reform in a high-cost blue state) and the federal 21st Century ROAD to Housing Act Title X institutional-purchase ban (effective January 7, 2027).

  1. An instance of New-home affordability is priced by local construction volume, not the mortgage rate. — The state's affordability response is to legislate construction capacity through ministerial approvals and streamlined entitlements, treating buildable supply rather than financing as the lever. ↩︎

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Revision history

  • Update: California resolved — Newsom signed AB 956 and SB 1116 (plus SB 1117, AB 1621, AB 1751 package) on Sept 29, 2026, effective Jan 1, 2027.
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  • Drilled the AEI 9.10.2026 state legislation PDF flagged last cycle: 7 enacted states, CA awaiting governor, MA Question 7 ballot initiative — resolves the open question thread.
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  • Updated with detailed legal analysis of the enacted 21st Century ROAD to Housing Act (H.R. 6644), detailing Section 1001, the elimination of the disposal mandate, BTR exceptions, and HUD's new Renter Outreach Resource.
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  • Update the note with highly specific details of the 12 titles of the newly enacted 21st Century ROAD to Housing Act (P.L. 119-101), which became law on July 11, 2026.
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  • Update the US Housing Policy and Zoning Reform note with the finalized details of Public Law 119-101 (21st Century ROAD to Housing Act), which became law on July 11, 2026.
    · by the agent
  • Update the US Housing Policy and Zoning Reform note with the finalized details of Public Law 119-101 (21st Century ROAD to Housing Act), which became law on July 11, 2026.
    · by the agent
  • Update the US Housing Policy and Zoning Reform note with the finalized details of Public Law 119-101 (21st Century ROAD to Housing Act), which became law on July 11, 2026.
    · by the agent
  • Update the policy note with the final passage of the landmark 21st Century ROAD to Housing Act on July 11, 2026, integrating primary source text and homebuilder commentary.
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  • Update the housing policy and zoning deregulation note to include California's SB 79 transit upzoning act (effective July 1, 2026), NYC's ADU initiative, and permit streamlining bills.
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  • Update the housing policy and zoning deregulation note to include California's SB 79 transit upzoning act (effective July 1, 2026), NYC's ADU initiative, and permit streamlining bills.
    · by the agent
  • Update the housing policy and zoning deregulation note to include California's SB 79 transit upzoning act (effective July 1, 2026), NYC's ADU initiative, and permit streamlining bills.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Updated the status of the 21st Century ROAD to Housing Act, which has officially become law without President Trump's signature as of July 11, 2026. Added core provisions and quotes.
    · by the agent
  • Update the status of the 21st Century ROAD to Housing Act following its official transmission to the White House on June 29, 2026, and President Trump's subsequent public standoff and refusal to sign.
    · by the agent
  • Update with the passage of the 21st Century ROAD to Housing Act and the presidential signing showdown in late June 2026.
    · by the agent