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ADU policy · Q2 2026 · CC-BY-4.0

US ADU market outlook 2026 — SB 9, AB 1033, and the state-equivalent ADU laws reshaping single-family zoning

Six years into California's by-right ADU revolution and two-plus years into Oregon, Washington, Vermont, Montana, Massachusetts, and Colorado's equivalents, where is the US ADU market in 2026?

By AskBaily Editorial · Published 2026-04-24 · 3,500 words · CC-BY-4.0
Executive summary

California crossed 25,000 ADU permits issued in 2023 and approximately 28,000 in 2024 per the California Department of Housing and Community Development's annual reports — roughly 18-20% of all residential permits issued statewide. Six years after SB 9's effective date, the regulatory architecture has matured: AB 1033 (2023) now allows ADUs to be sold separately as condos in jurisdictions that opt in; AB 976 (2023) made permanent the parking exemptions for ADUs near transit; SB 477 (2024) further streamlined the ministerial-approval pathway. The structural question for 2026 is no longer 'will California ADUs scale' (they have) but 'will other states converge on California's playbook'.

Oregon, Washington, Vermont, Montana, Massachusetts, and Colorado have all enacted state preemption laws between 2017 and 2024 that mandate ADU approval on most single-family lots in covered jurisdictions. The post-enactment permit data is encouraging: Oregon's HB 2001 + SB 1051 ADU permits roughly doubled from 2019 to 2024 (Portland metro especially); Washington's HB 1337 (effective 2024) is too early to read but local policy implementation is on schedule.

AskBaily Editorial's read of the 2026 ADU market is that California will continue to dominate national ADU-permit volume (likely 60-70% of total US ADUs in 2026), but the next-tier states will collectively contribute meaningfully more than they have historically. The combined under-the-radar story is regulatory convergence: the gap between 'California ADU rules' and 'normal-state ADU rules' is closing, which is structurally bullish for homeowner ADU feasibility nationwide.

Key findings

Section 1 — Market context

The ADU regulatory revolution started in California in 2016 with SB 1069 (and AB 2299), which preempted most local restrictions on ADUs and required ministerial approval. Subsequent legislation (SB 13 in 2019, AB 670 / 671 / 881 in 2019-2020, AB 68 / 670 in 2021, SB 9 in 2021, AB 976 in 2023, AB 1033 in 2023, SB 477 in 2024) progressively expanded by-right ADU rights, removed owner-occupancy requirements, and most recently allowed ADUs to be sold separately. The cumulative regulatory effect transformed California from one of the harder ADU-permitting environments in the country (2014-2016 baseline) to the easiest by a meaningful margin (2024-2026).

Oregon followed in 2017 with SB 1051 (banning owner-occupancy requirements) and 2019 with HB 2001 (the 'middle housing' law). Washington enacted HB 1110 and HB 1337 in 2023, both effective 2024. Vermont's HOME Act (Act 47, 2023) requires every Vermont municipality to allow at least one ADU on each single-family lot. Montana SB 528 (2023) requires cities of 5K+ to allow ADUs. Massachusetts's Affordable Homes Act (2024) creates statewide by-right approval. Colorado HB 24-1152 (2024) mandates by-right ADUs in cities of 1K+ effective mid-2025.

The remaining 40+ states do not have state-level preemption. ADU rules in those states are determined by municipal zoning codes, which produces wide variance. Some cities (Phoenix's Zoning Ordinance 608, Atlanta's allowance on most R-1 lots, Houston's deed-restriction-only framework) are functionally permissive. Other cities (most NJ suburbs, much of NY outside NYC, large portions of Chicago's outer wards, Florida's stricter HOA-dominated suburbs) remain restrictive.

The macro driver is housing supply. The post-2008 single-family-zoning constraint that generated much of the US's housing affordability problem is being unwound — slowly, unevenly, and with significant local resistance — by the ADU policy track. The Terner Center for Housing Innovation at UC Berkeley publishes the most comprehensive state-by-state ADU policy tracker; AskBaily Editorial's analysis builds on that work and adds 2025-2026 implementation data.

Section 2 — Data and findings

California's 2024 ADU permit total is approximately 28,000 per HCD annual reporting, of which approximately 4,500 are 'junior ADUs' (JADUs) — converted in-home units that share kitchen-and-bath plumbing with the primary dwelling. The remaining ~23,500 are detached or attached ADUs. Geographic concentration: Los Angeles County (~40% of state total), San Diego County (~12%), Bay Area combined (~22%), Sacramento metro (~8%), Central Valley (~10%), other (~8%).

AB 1033 separate-sale opt-in: approximately 30 California jurisdictions have opted in by Q1 2026, including the City of Los Angeles, Oakland, San Diego, San Jose, Berkeley, and several mid-size jurisdictions. The legal-and-financial mechanics of converting an ADU to a condo for separate sale are non-trivial (CC&Rs need to be drafted, lender financing needs to support the structure, the city needs to accept the condo subdivision). Industry observers report measurable but modest closed-sale volume — typical estimate is several hundred separately-sold ADUs in 2024-2025 — with the underwriting pipeline broadening through 2026.

Oregon ADU permits in 2024 totaled approximately 2,800 per state-level reporting, roughly double 2019 baseline. Portland metro accounts for the majority of volume; Bend, Eugene, and Salem each contribute meaningful but smaller cohorts. The Oregon trajectory under HB 2001 is the cleanest demonstration that state preemption produces measurable permit-volume increases without comparable local opposition.

Washington HB 1337 (effective 2024) is too early for clean permit data; local jurisdictions (Seattle, Bellevue, Tacoma, Spokane, Vancouver WA) are in mid-implementation. Industry observers expect Washington ADU permit volume to roughly double from a 2023 baseline of ~1,500 to ~3,000 in 2026, with Seattle metro dominating.

Vermont, Montana, Massachusetts, and Colorado are all in early-implementation phases. Vermont's HOME Act covers the smallest population (~640K) so absolute ADU-permit volume will be modest. Montana SB 528 covers cities of 5K+ which is meaningful demographically (Bozeman, Missoula, Billings, Great Falls, Butte) but the rural majority of the state is unaffected. Massachusetts and Colorado are higher-population states with substantial implementation upside; Massachusetts's by-right requirement covers Boston metro plus dozens of smaller cities, and Colorado's law covers the entire Denver-Boulder-Colorado Springs corridor.

Cost trends: ADU construction costs have inflated roughly in line with overall residential construction costs (BLS PPI residential construction inputs +35-40% since January 2020). Typical detached ADU costs in 2026 dollars: $250-450/sf for 600-1000 sf units, with the upper end concentrated in coastal California and Pacific Northwest. Junior ADU conversions are substantially cheaper ($75-150K typical) because they reuse existing structure. Pre-fab and modular ADU vendors (Cover, Abodu, Studio Shed, Boxabl, others) have grown but remain a minority of total volume — typical estimates are 5-15% of California ADU volume, with site-built remaining the majority.

Section 3 — What it means for homeowners

For homeowners considering an ADU in 2026, the regulatory environment is substantially more permissive than it was even three years ago. In California, Oregon, Washington, Vermont, Montana, Massachusetts (effective 2025), and Colorado (effective 2025), state preemption laws meaningfully constrain a city's ability to deny an ADU on a single-family lot. The practical implication is that 'is an ADU allowed on my lot' is increasingly a yes-by-default in covered jurisdictions; the harder question is the address-specific layer — lot size, setbacks, FAR, historic-overlay status, slope and access, utility-capacity constraints.

AB 1033's separate-sale option is the strategically interesting California-specific development. A homeowner who builds an ADU and later wishes to sell it to fund retirement or downsize-in-place can do so as a condo unit in opt-in jurisdictions. The market is still maturing — comp-sale data is sparse, lender willingness varies, and CC&R drafting is lawyer-time-intensive — but the structural option is meaningful. Homeowners building an ADU in 2026 should evaluate whether their jurisdiction has opted in and what the path to AB 1033-compliant separate sale would require.

Cost expectations: a homeowner planning an ADU should budget $250-450/sf for 600-1000 sf detached units (so $150K-$450K typical), substantially less for JADU conversions, and substantially more for upper-quartile finishes or sloped/access-constrained lots. ADU-specific financing options (renovation loans, HELOC, ADU-specific construction loans from California credit unions and a small number of national lenders) have expanded; comparison-shopping across at least three lenders typically yields meaningful APR variance.

Permit timelines have improved meaningfully under SB 9's ministerial-approval pathway and post-2020 reforms. California ADU permits typically issue in 4-12 weeks from complete submittal in major California jurisdictions; Oregon and Washington run similar; Northeast and Mountain West timelines have improved but lag California somewhat (8-16 weeks typical in 2026). Homeowners should plan total project timelines (design, permits, construction, inspections, certificate of occupancy) of 9-18 months for a straightforward detached ADU.

Section 4 — What it means for contractors

For contractors, the ADU market is now mature enough to specialize meaningfully. A contractor whose mix is 30%+ ADUs is a recognizable specialty in California (Los Angeles, San Diego, Bay Area especially), Portland, Seattle, and Denver metros. The unit economic for ADU specialists is generally favorable: standardized scopes, repeat material specifications, accumulated permit-process knowledge, and the ability to develop reusable design libraries that compress design-time.

The structural strategic question for ADU specialists is whether to integrate vertically (offer design + permit + build in a single contract), partner with architects and pre-fab vendors (Cover, Abodu, Studio Shed, Snap ADU, etc.), or stay generalist (any ADU project welcome but no special branding). Each posture is defensible. The vertically-integrated 'design-build ADU specialist' is the fastest-growing model in California per industry-observer reports and is the model that AskBaily's matching engine biases toward for ADU-tagged projects.

Pricing posture varies substantially by metro. California coastal markets (LA, SD, Bay Area) clear at $300-500/sf typical for site-built ADUs; California inland markets (Inland Empire, Central Valley) at $225-350/sf; Pacific Northwest at $275-425/sf; Mountain West (Denver, Boise, SLC) at $225-375/sf; Northeast (Boston, MA Affordable Homes Act jurisdictions) at $325-475/sf. A contractor pricing meaningfully above market clears fewer jobs but typically with better margins; below market clears more but on tighter margins.

The longer-tail strategic question for contractors is whether the AB 1033 separate-sale market creates a new business model. A contractor who builds a high-quality ADU and helps the homeowner navigate the AB 1033 condo conversion is delivering a product (saleable real estate) rather than just a service (construction). Industry observers note this could grow into a meaningful new contractor business model in California over the next 24-36 months; equivalent legal mechanisms in other states are not yet present but could emerge if AB 1033 proves successful.

Section 5 — AskBaily methodology and provenance

AskBaily's ADU market dataset combines four sources. (1) State-level permit-issuance data from California HCD's annual ADU report, Oregon DLCD's middle-housing tracker, Washington Department of Commerce, and equivalent state-housing offices. (2) Municipal-level permit data from 30+ California jurisdictions' open-data portals (LA Building & Safety, San Diego Development Services, Berkeley GIS, etc.). (3) AB 1033 opt-in tracking from the Casita Coalition's monthly registry. (4) Cost-trend tracking from a curated sample of contractor bid disclosures normalized to per-square-foot, finish-tier-adjusted, and inflation-adjusted to Q1 2026 dollars.

The Terner Center for Housing Innovation at UC Berkeley publishes the most comprehensive state-by-state ADU policy tracker; AskBaily's policy summary builds on that work and extends with 2024-2026 implementation data not yet in the Terner published series.

Limitations: state-level permit reporting lags 6-12 months in many cases; 2025 data is partial as of Q1 2026 publication. Cost-trend data is sample-based (40-100 projects/quarter) and reported as ranges. AB 1033 opt-in count is monthly-refreshed but separate-sale closed-volume data is not centrally reported and is therefore industry-observer triangulated rather than firmly sourced.

AskBaily Editorial publishes this analysis under CC-BY-4.0. Trade press, journalists, and academic researchers may reuse with attribution. Companion data extract at /api/v1/research/adu-market, refreshed quarterly. State-housing-office contacts and policy analysts may submit corrections via [email protected].

Citations

  1. [1]California Department of Housing and Community Development, Annual ADU Permit Reports, 2018-2024. https://www.hcd.ca.gov/
  2. [2]California Senate Bill 9 (2021), the California Housing Opportunity and More Efficiency Act. https://leginfo.legislature.ca.gov/
  3. [3]California Assembly Bill 1033 (2023), ADU separate sale. https://leginfo.legislature.ca.gov/
  4. [4]California Assembly Bill 976 (2023), permanent ADU parking exemptions. https://leginfo.legislature.ca.gov/
  5. [5]California Senate Bill 477 (2024), streamlined ministerial ADU approval. https://leginfo.legislature.ca.gov/
  6. [6]Oregon House Bill 2001 (2019), middle-housing preemption. https://olis.oregonlegislature.gov/
  7. [7]Oregon Senate Bill 1051 (2017), ADU owner-occupancy preemption. https://olis.oregonlegislature.gov/
  8. [8]Washington House Bill 1337 (2023), two-ADU-per-lot by-right. https://lawfilesext.leg.wa.gov/
  9. [9]Washington House Bill 1110 (2023), middle-housing preemption. https://lawfilesext.leg.wa.gov/
  10. [10]Vermont Act 47 (2023), HOME Act statewide ADU mandate. https://legislature.vermont.gov/
  11. [11]Montana Senate Bill 528 (2023), municipal ADU preemption. https://leg.mt.gov/
  12. [12]Massachusetts Affordable Homes Act (2024), statewide by-right ADU approval. https://malegislature.gov/
  13. [13]Colorado House Bill 24-1152 (2024), municipal ADU preemption. https://leg.colorado.gov/
  14. [14]Terner Center for Housing Innovation, UC Berkeley, ADU policy tracker. https://ternercenter.berkeley.edu/
  15. [15]Casita Coalition, AB 1033 opt-in jurisdiction registry. https://www.casitacoalition.org/
  16. [16]Bureau of Labor Statistics, PPI Series WPS3911 — residential construction inputs. https://www.bls.gov/ppi/
  17. [17]AskBaily Research, ADU Market Outlook Dataset. https://askbaily.com/api/v1/research/adu-market

Frequently asked questions

Can my city deny my ADU permit if I'm in California?

Generally no, if your project meets state-level by-right criteria — lot in an R-1 zone, ADU within size and setback minima, no historic-overlay constraints. Cities can require certain layered approvals (HPOZ review for historic homes, coastal commission review for coastal-zone parcels, hillside review in steep terrain) but cannot deny outright. The harder question is typically lot-and-utility specifics: setback exceptions, FAR limits in some jurisdictions, sewer-capacity issues. Address-specific feasibility is best confirmed with a licensed contractor or permit expediter.

How does AB 1033 separate-sale actually work?

The homeowner builds an ADU on their primary residence, then (in an opt-in jurisdiction) initiates a condo subdivision that creates two units (the primary residence and the ADU) plus shared common areas. CC&Rs are drafted to govern the relationship. The ADU can then be sold separately to a buyer who finances it as a condo. The mechanics are non-trivial — lawyer time, lender alignment, CC&R drafting — but the structural pathway is real in opt-in jurisdictions.

Is California still the dominant ADU market?

Yes, by a wide margin. California issued ~28,000 ADU permits in 2024; the next-tier states (Oregon, Washington, Massachusetts, Colorado, Vermont, Montana) collectively likely run 5,000-8,000 in 2024-2025. The gap will narrow over 2026-2028 as state-preemption laws in other states mature, but California is structurally favored by policy maturity, market depth, and accumulated contractor capacity.

What does an ADU cost in 2026?

Detached site-built ADUs typically run $250-450/sf in 2026 dollars, so $150K-$450K for 600-1000 sf units. Junior ADU conversions are substantially cheaper ($75-150K typical). Pre-fab vendors offer turnkey pricing in the $200K-$400K range for similar size units; site-built can be more or less depending on lot conditions. Upper-quartile finishes, complex utility runs, sloped lots, or coastal-zone constraints push the upper end higher.

What's the realistic ADU project timeline?

Plan 9-18 months end-to-end for a straightforward detached ADU. Design and engineering: 2-4 months. Permitting: 4-12 weeks in most California jurisdictions (longer in restricted overlay zones), 8-16 weeks in most Oregon/Washington/Northeast jurisdictions. Construction: 5-10 months for site-built; 3-6 months for pre-fab-on-foundation. Inspections and certificate of occupancy: 1-3 weeks. JADU conversions are substantially faster (3-6 months end-to-end typical).

Can homeowners sell an ADU separately in non-California states?

Generally no. AB 1033 is California-specific. Other states allow ADUs to be rented but not sold separately as condos under current law. Some homeowner activists are pushing for AB 1033-equivalent legislation in Oregon, Washington, and Vermont; none has passed as of Q1 2026.

How does AskBaily handle ADU project matching?

AskBaily's matching engine has an ADU-specialty lane that filters for documented prior ADU project completions and contractor familiarity with the relevant state and municipal regulatory layers (SB 9, AB 1033 opt-in, Oregon HB 2001, Washington HB 1337, etc.). For California ADU projects, matching turnaround is typically 24-72 hours; for other-state ADU projects (Oregon, Washington, Massachusetts, Colorado, Vermont, Montana) coverage is uneven and matching may route to a manual operator queue.

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