Two-story ADU with dark vertical siding and a bright yellow door
Mayberry Workshop logo

Adam Mayberry, AIA, MRED

Managing Principal, Mayberry Workshop

Mayberry Workshop

New Housing Opportunities

What California law allows now, and what changes on January 1, 2027

Two-story white farmhouse-style home with board-and-batten siding and a wood fence

Davis

San Francisco

San Jose

San Luis Obispo

San Diego

Mayberry Workshop · 02

Adam Mayberry

AIA · NCARB · MRED

Architect and real estate developer leading Mayberry Workshop, a California architecture and design-build practice focused on ADUs, missing-middle and multifamily housing.

Training since 2004
Practicing since 2015

SLIDE 5 - Update.png

Today · Gov. Code §§66314 & 66323

ADU LAWS

Five legal homes on one single-family lot

1

Existing single-family home

Establishes eligibility for ADUs and a JADU.

1

ADU under §66314

Ministerial approval; detached, attached or new; 800 sf by right.

2

ADUs under §66323

Allowed when one ADU converts existing space, such as a garage.

1

Junior ADU under §66323

Up to 500 sf in the home; no owner-occupancy; not counted.

= 5 units: 1 primary + 3 ADUs + 1 JADU

Aerial view of a corner lot with a main house and several small white ADUsBlack-sided detached ADU behind a white Victorian home

New Jan 1, 2027 · AB 956

Two detached new-build ADUs

Cities must approve two detached, new-construction ADUs on a single-family lot, up from one.

Each can be capped at 800 sf; 4′ side and rear setbacks and the 16′–18′ height limits still apply. If no JADU proposed or previously approved.

Mayberry Workshop · 03

Mayberry Workshop · 04

Today · SB 9 (2021)

Duplexes and lot splits, by right

Limits · SB 450 updates (2025)

  • Parking: 1 space per unit max; none within ½ mile of transit
  • Excluded: historic districts and high fire-hazard zones
  • Not on homes tenant-occupied in the past 3 years
  • SB 450: objective standards only, 60-day decision clock

Two-unit build

  • Two units per single-family lot
  • Ministerial: no hearing, no CEQA
  • Units of at least 800 sf allowed
  • 4′ side and rear setbacks

Urban lot split

  • One lot becomes two, each at least 1,200 sf
  • Split no more unevenly than 60/40
  • Up to 4 units in total
  • 3-year owner-occupancy affidavit
Side-by-side two-story duplex with twin garages and front porches

Starter Home Revitalization Act

Small-lot subdivisions of up to 10 homes

SB 684 · 2023

  • Multifamily-zoned infill lots, up to 5 acres
  • Up to 10 lots and 10 homes, approved ministerially
  • No CEQA; homes average 1,750 sf or less
  • Max 1 parking space per home

SB 1123 · 2024

  • Extends the Act to vacant single-family-zoned lots, up to 1.5 acres
  • Same 10-home, ministerial path
  • In effect since July 1, 2025
  • Remainder Lot

SB 1116 · Applications from Jan 1, 2027

  • 5-acre cap replaced by an urban infill test
  • Complex 66% minimum-density rules dropped
  • Broader definition of a “vacant” lot
  • FAR floor raised to 1.25; front setbacks capped at 10′
  • Voids covenants that block projects (HOAs excepted)
  • Cities submit ordinances to HCD within 60 days
Row of small two-story starter homes along a landscaped walkwaySmall-lot homes lining a new private street

Mayberry Workshop · 05

For your clients

Every lot may hold more homes than the listing says

  • A single-family lot can hold 5 legal units under today’s ADU law
  • From Jan 1, 2027, AB 956 allows two detached new-build ADUs
  • SB 1116 widens the 10-home starter home path
Mayberry Workshop logo

Questions?

Adam Mayberry, AIA, MRED

adam@mayberryworkshop.com

(408) 582-4567

mayberryworkshop.com

Mayberry Workshop · 06