Housing Policy Explainers
Recent residential regulations that change what you can build and what you must submit, each marked with its state or city. Lot splits, ADU expansions, middle housing, streamlined approvals, and energy codes in plain English.
2025 Title 24 Energy Code
California 2025 Building Energy Efficiency Standards (Title 24, Part 6)
Applies to permit applications filed on or after January 1, 2026, and makes heat pumps the prescriptive baseline for both space and water heating in new single-family homes, alongside updated solar PV sizing requirements. The CEC estimates $4.8 billion in energy savings over 30 years.
SB 79 Transit-Oriented Housing
California SB 79 (2025), Abundant and Affordable Homes Near Transit Act
Requires local agencies in eight urban transit counties to allow taller, denser multifamily housing (minimum 5 units, with tiered height and density standards) within roughly a half mile of qualifying rail and bus rapid transit stops. Signed October 10, 2025, effective July 1, 2026. (Note: often misremembered as 'SB 78' — California's SB 78 (2025) is an unrelated Caltrans highway-safety reporting bill.)
AB 130/SB 131 CEQA Reform
California AB 130 and SB 131 (2025 budget trailer bills)
Signed June 30, 2025, these bills create a statutory CEQA exemption for qualifying infill housing on sites up to 20 acres, impose a 30-day approval deadline, and limit CEQA review for housing projects that miss an exemption by a single condition. Considered the most significant CEQA overhaul for housing in decades.
Zone 0 Ember-Resistant Defensible Space
California AB 3074 (2020), SB 504 (2024), AB 1455 (2025), and Executive Order N-18-25
Directs the Board of Forestry to adopt regulations requiring an ember-resistant zone with no combustible materials within 5 feet of structures in high fire hazard severity zones. Executive Order N-18-25 set a December 31, 2025 rulemaking deadline, but the Board paused and rulemaking continued into 2026 — new homes and remodels in fire zones will be directly affected.
SB 15 Small Lots
Texas SB 15 (2025), Local Gov. Code ch. 211 amendments
Prohibits large Texas cities (over 150,000 population in counties of 300,000+) from requiring residential lots larger than 3,000 sq ft in new subdivisions, and caps setback, parking, and open-space mandates on small lots. Signed June 20, 2025, effective September 1, 2025.
SB 684/1123 Starter Home Subdivisions
California SB 684 (2023) and SB 1123 (2024), Starter Home Revitalization Act
Creates a streamlined, CEQA-exempt ministerial path for subdividing lots into up to 10 starter homes (max average 1,750 sq ft) in multifamily zones, with SB 1123 extending it to vacant single-family lots up to 1.5 acres effective July 1, 2025. Agencies must approve or deny within 60 days or the project is deemed approved.
AB 2533 Unpermitted ADU Amnesty
California AB 2533 (2024), amending Gov. Code § 66332
Expands the ADU amnesty program to unpermitted ADUs and JADUs built before January 1, 2020 (previously 2018), and bars cities from imposing impact fees on those legalizations. Effective January 1, 2025; jurisdictions must publish legalization checklists and allow confidential third-party inspections.
SB 1211 Multifamily ADU Expansion
California SB 1211 (2024), amending Gov. Code §§ 66314 & 66323
Raises the cap on detached ADUs allowed on multifamily properties to up to eight, and prohibits local agencies from requiring replacement of uncovered parking spaces demolished to build an ADU. Effective January 1, 2025.
2021 Washington State Energy Code
Washington 2021 WSEC, Chapter 51-11R WAC
Took effect March 15, 2024 with a revised energy-credit system that strongly favors electric heat pumps: homes using combustible fuels like natural gas must earn more efficiency credits than all-electric heat pump homes. New homes need 5-9 credits depending on size.
HB24-1152 ADU Rights
Colorado HB24-1152 (2024)
Requires subject jurisdictions (metro-area cities over 1,000 residents) to allow one ADU wherever single-family detached homes are permitted, via administrative approval, effective June 30, 2025. It also voids HOA prohibitions on ADUs and funds a $13 million grant program including pre-approved plans.
HB 2720 Casita Law
Arizona HB 2720 (2024), A.R.S. § 9-461.18
Requires Arizona cities with more than 75,000 residents to allow at least one attached and one detached ADU ('casita') on any lot where a single-family home is allowed, with limits on parking mandates, setbacks, and size formulas. Signed May 2024, with city compliance required by January 1, 2025.
SB 1537 Housing Production Package
Oregon SB 1537 (2024)
Governor Kotek's housing package, signed May 6, 2024, creates the Housing Accountability and Production Office, requires cities to grant mandatory adjustments to certain development standards for qualifying housing projects, and directs $500 million toward housing infrastructure and moderate-income housing financing.
Local Law 154 All-Electric Buildings
New York City Local Law 154 (2021)
Prohibits onsite combustion of fuels emitting more than 25 kg CO2/MMBtu in new buildings, effectively banning gas stoves, boilers, and oil heat in new construction. Applies to new buildings under 7 stories permitted since January 1, 2024, and extends to buildings 7 stories and taller in July 2027; appellate courts upheld the ban in 2026.
City of Yes Housing Rezoning
New York City 'City of Yes for Housing Opportunity' zoning text amendment (2024)
Citywide zoning overhaul approved by the City Council on December 5, 2024, projected to enable roughly 80,000 new homes over 15 years. It legalizes ADUs up to 800 sq ft on one- and two-family lots (owner-occupied, with flood-zone and historic-district exclusions), adds transit-oriented and town-center density, and reduces parking mandates.
SB 423 Streamlined Approvals
California SB 423 (2023), amending Gov. Code § 65913.4
Extends and expands SB 35's streamlined ministerial approval process for multifamily infill housing through January 1, 2036, applying in jurisdictions behind on RHNA targets or without a compliant housing element. Effective January 1, 2024.
AB 1033 ADU Condo Sales
California AB 1033 (2023), amending Gov. Code § 66342
Allows cities and counties to adopt ordinances permitting ADUs to be sold separately from the primary home as condominiums. Effective January 1, 2024; it is opt-in, and only a handful of jurisdictions (including San Jose and Santa Monica) had adopted ordinances as of early 2026.
HB 1110 Middle Housing
Washington E2SHB 1110 (2023)
Requires most Washington cities to allow middle housing — duplexes up to sixplexes, townhouses, cottage housing, and stacked flats — on lots zoned single-family, with density tiers based on city size. Central Puget Sound cities had to comply by June 30, 2025; other cities phase in through 2027.
HB 1337 ADU Reform
Washington EHB 1337 (2023)
Requires cities and counties to allow two ADUs per lot with single-family homes, eliminates owner-occupancy requirements, and caps ADU impact fees at 50% of those for the principal unit. Local compliance was due June 30, 2025, with streamlined permitting starting July 1, 2025.
Montana Miracle Duplex & ADU Laws
Montana SB 323 and SB 528 (2023)
SB 323 requires cities of 5,000+ residents to allow duplexes wherever single-family homes are permitted, and SB 528 requires all municipalities to allow at least one ADU per single-family lot. Blocked by injunction in late 2023, the laws were reinstated by the Montana Supreme Court in 2024 and upheld as serving a legitimate government purpose by a district court in March 2025.
SB 9 Lot Splits
California SB 9 (2021), Gov. Code §§ 65852.21 & 66411.7
Requires ministerial approval of up to two units on single-family lots and one urban lot split, enabling up to four units per former single-family parcel. Effective January 1, 2022; a 2024 court ruling limited its application to charter cities, keeping implementation in flux.