Statistics
Junior ADU statistics
25 of 41 figures are HyreADU calculations. The statutory ceiling is 500 square feet inside the house; on the Los Angeles permit record junior units are 9.6% of ADU permits and reach occupancy 122 days sooner at the median.
Written by HyreADU Research Desk Primary-source research and data analysis
Audited by HyreADU Research Desk Statutory citation and classifier audit
How to use this page
A junior accessory dwelling unit is a separate statutory creature, not a small ADU. Government Code section 66313(d) defines it as “a unit that is no more than 500 square feet of interior livable space in size and contained entirely within a single-family residence”, and section 66333(d) requires it to be “constructed within the walls of the proposed or existing single-family residence”.
It needs a separate exterior entrance and an efficiency kitchen, it may share a bathroom with the house, and — unlike an ordinary ADU — it still carries an owner-occupancy condition.
That condition was narrowed rather than removed. Since 1 January 2026, section 66333(b), as amended by AB 1154 (Stats. 2025, Ch. 507), requires owner-occupancy only where the junior unit shares sanitation facilities with the existing structure.
The measured picture, and it is Los Angeles only. 3,778 of 39,278 ADU-adding permits in our extract of the City of Los Angeles permit file are JADU-flagged — 9.62%, roughly one ADU permit in ten.
Median time from permit issue to certificate of occupancy is 387 days against 509 days for a standard ADU, and the junior curve sits above the standard curve at every horizon we measured.
The size distribution says something the study did not report. Of the 2,238 JADU-flagged permits carrying a usable floor-area value, 23.95% sit above the 500 square foot ceiling on the city’s own field. Both readings of that are set out below.
There is no statewide junior ADU count, here or anywhere. HCD’s Annual Progress Report Table A2 has no JADU unit category; junior units appear there only where a jurisdiction coded them as ADUs. A California figure would be an invention.
25 of 41 figures on this page are HyreADU calculations (25 hyreadu calculation, 16 agency published). Not legal advice.
Read this before you quote anything here
- Every count and duration on this page is the City of Los Angeles
Los Angeles is a very large ADU market and the only jurisdiction this desk has found publishing a departmental ADU flag on a complete permit extract.
It is still one city, with one housing stock and one set of departmental habits. 9.6% is a Los Angeles share, not a California one and certainly not a national one.
- There is no statewide junior ADU count, and we will not construct one
HCD’s Annual Progress Report Table A2 has no separate JADU unit category. Junior units appear in the state file only where the reporting jurisdiction chose to code them as ADUs, and there is no way to separate them afterwards. Any statewide JADU figure you encounter should be traced before it is used.
- The JADU flag is administrative, not architectural
Our classification rests on how LADBS coded the permit record. A unit meeting the statutory definition but permitted as an ADU sits in the standard group, and the reverse also happens.
The clearest evidence of that is on this page: 23.95% of JADU-flagged permits with a usable floor-area value are above the 500 square foot statutory ceiling on the city’s field.
Treat 9.6% as an order of magnitude rather than a precise share.
- A duration percentile is not a build time, and the frame is right-censored
The duration measured is permit issue to certificate of occupancy — a clock that includes construction, inspection, financing gaps, contractor turnover and the periods when nothing happens at all.
Permits issued recently have had less time to complete, so the observed shares at long horizons are computed only over permits old enough to have reached them. The construction duration study carries the sensitivity work.
- Not legal advice, and not a feasibility opinion on your house
Whether a junior ADU is possible in your home depends on the existing structure, the local ordinance, the building and fire code path, and facts we cannot see. Converting interior space to create a dwelling involves structural, electrical, plumbing and fire-safety work that must be carried out under permit by licensed professionals.
Read the provenance, not just the number
Two kinds of fact sit on this page and the whole value of it is keeping them apart.
Agency published — the statutory rules. 500 square feet; inside the walls; one per lot; separate entrance; efficiency kitchen; 60-day ministerial decision; no parking; a deed restriction. Quoted from the Government Code as retrieved on 2026-09-05, with § 66333 re-verified on 2026-09-07.
HyreADU calculation — every count, share, percentile and floor-area figure, computed from the City of Los Angeles building permit extract. These are not figures published by the City. The method lives on the junior ADU study, the construction duration study and the size distribution study.
A citation warning that matters here more than almost anywhere. Junior ADUs sat at Government Code section 65852.22 until SB 477 (Stats. 2024, Ch. 7) repealed it and moved the scheme into Chapter 13 with effect from 25 March 2024.
SB 543 (Stats. 2025, Ch. 520) then renumbered part of the chapter again from 1 January 2026.
Most JADU guidance still in circulation cites section 65852.22, which no longer exists. The current provisions are §§ 66333 to 66339.5, and the definition is at § 66313(d). The owner-occupancy study carries the full concordance.
The figures most worth knowing
Full method on the junior ADU study. A permit share is not a housing-stock share.
The statutory rules, and where a junior ADU differs from an ADU
Almost every wrong answer about junior ADUs comes from treating them as small ADUs.
They are a separate statutory creature with a separate rule set, and the differences run in both directions — a JADU is smaller and more constrained on location, and freer on parking, utilities and fire classification.
Every value in this table is agency published; it is the Legislature’s number, not ours.
| Question | Accessory dwelling unit | Junior accessory dwelling unit | Authority |
|---|---|---|---|
| Maximum size | A city’s maximum must allow at least 850 sq ft of interior livable space, or 1,000 sq ft with more than one bedroom. A floor on what a city may impose. | No more than 500 sq ft of interior livable space. A hard statutory ceiling, not a floor. | § 66321(b)(2) (ADU); § 66313(d) (JADU). |
| Where it can be | Attached, detached, or converted from existing space anywhere on the lot that meets the standards. | Contained entirely within a single-family residence, and “constructed within the walls of the proposed or existing single-family residence”. It cannot be a separate building, and it cannot be in a detached garage. | § 66313(d); § 66333(d). |
| Owner-occupancy | Prohibited. No standard beyond § 66314 may be imposed, “including an owner-occupant requirement”, and the prohibition no longer sunsets. | Required, in narrowed form. Since 1 January 2026 a JADU ordinance must require owner-occupancy only where the unit “has shared sanitation facilities with the existing structure”, with an exception for a governmental agency, land trust or housing organization owner. | § 66315 (ADU); § 66333(b) as amended by AB 1154, Stats. 2025, Ch. 507. |
| Bathroom | Its own sanitation facilities — a complete independent living facility. | May share a bathroom with the house. The provision that makes a JADU buildable in a bedroom-sized space — and the provision that triggers the owner-occupancy condition. | § 66333(b) and the § 66313(d) definition. |
| Kitchen | A full kitchen. | An efficiency kitchen: a cooking facility with appliances, a food preparation counter and storage cabinets of a size in proportion to the unit. | § 66333(f). |
| Entrance | Its own access under the applicable standards. | A separate entrance from the main entrance to the single-family residence. | § 66333(e). |
| Parking | At most one space, with six independent routes to zero. | None may be required. | §§ 66314(d)(10), 66322 (ADU); § 66334 (JADU). |
| Utility connection fees | Constrained; no impact fee at or below 750 sq ft of interior livable space. | Not treated as a new residential use for the purpose of a new or separate utility connection, and no connection fee or capacity charge on that basis. | § 66311.5(c)(1) (ADU); § 66338 (JADU). |
| Fire and life protection | A dwelling unit for the applicable code purposes. | Not considered a separate or new dwelling unit for fire or life protection purposes. | § 66337. |
| Approval | Ministerial for the § 66323 categories, within 60 days. | Ministerial within 60 days. | § 66317 (ADU); § 66335 (JADU). |
| Separate sale | Narrow routes exist — the nonprofit pathway and the AB 1033 condominium mechanism. | Prohibited. A recorded deed restriction running with the land must prohibit sale separate from the single-family residence. | § 66333(c). |
California Government Code, Chapter 13, as it stands after AB 1154 and SB 543 took effect on 1 January 2026. Retrieved 2026-09-05; § 66333 re-verified against leginfo 2026-09-07, enactment line “Amended by Stats. 2025, Ch. 507, Sec. 1. (AB 1154) Effective January 1, 2026.”
The asymmetry is the whole story of the category. The feature that makes a junior ADU cheap to build — sharing the bathroom — is the feature that triggers the owner-occupancy condition.
An owner who wants the unit free of that condition has to build a separate bathroom, which is a large share of what a JADU costs.
That trade-off is the central design decision, and it is a statutory trade-off rather than a construction one.
How many there actually are, in the highest-volume California ADU jurisdiction
HyreADU calculations from a public municipal dataset, not figures published by the City of Los Angeles. The frame is every permit adding a net ADU or junior ADU, issued from 1 January 2020, with supplemental permits removed so one project is not counted twice.
| Measure | Value | What it is | Class |
|---|---|---|---|
| LADBS permit rows downloaded | 409,619 | The full extract, resource pi9x-tg5x on data.lacity.org, rows updated 2026-08-31. | HyreADU calculation |
| ADU-flagged rows | 41,374 | Records carrying an ADU or JADU indicator in the source data. | HyreADU calculation |
| Supplemental permits excluded | 2,095 | Removed so a single project is not counted twice. | HyreADU calculation |
| Analysis frame | 39,278 | The denominator for every share on this page. | HyreADU calculation |
| JADU-flagged | 3,778 | 9.62% of the frame. | HyreADU calculation |
| Standard ADU | 35,500 | 90.38% of the frame. | HyreADU calculation |
| JADU occupancy events observed | 2,447 | Permits in the junior group that reached a certificate of occupancy or a permit final inside the observation window. | HyreADU calculation |
| Standard ADU occupancy events observed | 22,525 | The equivalent for the standard group. | HyreADU calculation |
| Whole-frame completion events | 24,972 | Of which 24,876 via certificate of occupancy and 96 via permit final. | HyreADU calculation |
Composition of the Los Angeles ADU permit analysis frame. HyreADU extract of LADBS resource pi9x-tg5x, rows updated 2026-08-31.
The share is a share of permit records, not of buildings standing today. It says roughly one in ten ADU permits pulled in Los Angeles since 2020 is for a junior unit.
It does not say one in ten Los Angeles ADUs is a JADU: the permit record does not reach back far enough, and completion rates differ between the two groups.
Junior ADUs reach occupancy sooner, at every horizon
Time from permit issue to certificate of occupancy, on identical definitions and the same observation window for both groups.
The advantage is largest early and narrows over three years, which is the shape you would expect if junior units are a faster job that finishes when it finishes, while the standard group contains both quick projects and a long tail of very slow ones that eventually complete.
| Measure | Junior ADU | Standard ADU | Difference | Class |
|---|---|---|---|---|
| Permits in group | 3,778 | 35,500 | — | HyreADU calculation |
| Occupancy events observed | 2,447 | 22,525 | — | HyreADU calculation |
| 25th percentile | 212 days | 301 days | 89 days faster | HyreADU calculation |
| Median | 387 days | 509 days | 122 days faster | HyreADU calculation |
| 75th percentile | 908 days | 1,086 days | 178 days faster | HyreADU calculation |
| Within 1 year | 47.3% | 34.0% | +13.3 points | HyreADU calculation |
| Within 18 months | 63.2% | 53.4% | +9.9 points | HyreADU calculation |
| Within 2 years | 70.3% | 64.5% | +5.8 points | HyreADU calculation |
| Within 3 years | 78.4% | 75.1% | +3.2 points | HyreADU calculation |
Permit-to-occupancy duration by unit type, City of Los Angeles. HyreADU calculation from LADBS pi9x-tg5x. The median across the whole ADU frame is 499 days, so a junior unit is 112 days quicker than the typical ADU permit of any kind.
Read the narrowing gap carefully. 13.3 points at one year, 3.2 points at three. That is not evidence that a junior ADU is a third of the work. It is evidence that it clears the pipeline sooner.
The same comparison, drawn
Three percentiles, two groups, one chart. The junior unit is faster at all three, and the absolute advantage grows with the percentile because the tail is where the standard ADU group accumulates its slow projects.
| Percentile | Junior ADU | Standard ADU | Absolute gap | Gap as a share of the standard figure | Class |
|---|---|---|---|---|---|
| 25th | 212 days | 301 days | 89 days | 29.6% | HyreADU calculation |
| 50th (median) | 387 days | 509 days | 122 days | 24.0% | HyreADU calculation |
| 75th | 908 days | 1,086 days | 178 days | 16.4% | HyreADU calculation |
HyreADU calculation. The relative advantage is largest at the 25th percentile and smallest at the 75th, which is the same finding as the narrowing cumulative gap seen from the other direction.
How big a junior ADU actually is — and the quarter that does not fit
Junior ADU size is the part the parent study did not report, and it is the reason this digest exists as more than a summary.
Of the 2,238 JADU-flagged permits carrying a usable floor-area value in the LADBS field, the median is 409 sq ft — 81.8% of the 500 square foot statutory ceiling.
But 23.95% are above 500 square feet on that field, and the 90th percentile is 1,378 sq ft. That gap has to be explained, not deleted.
| Measure | JADU-flagged permits | New-construction ADU permits, for contrast | Class |
|---|---|---|---|
| Permits with a usable floor-area value | 2,238 | 8,536 | HyreADU calculation |
| 10th percentile | 265 sq ft | 460 sq ft | HyreADU calculation |
| 25th percentile | 353 sq ft | 670 sq ft | HyreADU calculation |
| Median | 409 sq ft | 920 sq ft | HyreADU calculation |
| 75th percentile | 499 sq ft | 1,194 sq ft | HyreADU calculation |
| 90th percentile | 1,378 sq ft | 1,343 sq ft | HyreADU calculation |
| At or under the 500 sq ft JADU ceiling | 76.05% | — | HyreADU calculation |
| Above 500 sq ft on the LADBS field | 23.95% | — | HyreADU calculation |
| Median as a share of the JADU statutory ceiling | 81.8% | — | HyreADU calculation |
| Median JADU against median new-construction ADU | 44.5% | 100% | HyreADU calculation |
HyreADU calculation from LADBS resource pi9x-tg5x, rows refreshed 2026-08-30. New-construction figures are the whole-city detached and new-build ADU distribution, printed only as a contrast — the size distribution study is where that distribution belongs.
Two honest readings of the 24.0%, and we cannot choose between them from the file. Measurement basis: the statute limits interior livable space, a defined measure; the LADBS field is a square footage recorded for permitting purposes, and a permit that also covers work outside the junior unit will carry a larger number.
On that reading nothing is out of compliance and the field is simply measuring a different thing. Classification: the department’s junior-ADU flag is an administrative code, and a project that is not a statutory JADU can carry it.
On that reading the flag is over-inclusive and the true junior share is below 9.6%.
What we will not do is present either reading as established, or quietly drop the rows above the ceiling to make the distribution tidy. We publish no finding that any permit was unlawful, and none of this is a compliance assessment of any project.
Why the cheapest and fastest category is the least used
We have a measured share (9.6% in Los Angeles) and a measured advantage (122 days at the median). We do not have a measured cause. What follows is HyreADU analysis, and each block says what would be needed to test it.
1. It costs you a room in your own house
A junior ADU must be constructed within the walls of the existing single-family residence. Every square foot of it is a square foot the household stops using. A backyard ADU adds space to the property; a junior ADU reallocates it.
HyreADU analysis. This is the most plausible explanation on the structure of the rule alone, and the hardest to test — it needs household-level data on why owners chose one route over the other, which no permit record contains.
The median junior unit on our figures is 409 sq ft, which is a bedroom and a bathroom’s worth of house.
2. The owner-occupancy condition survived, and it is triggered by the cheap design
California permanently prohibited local owner-occupancy requirements for ordinary ADUs. It did not do so for junior units: the requirement stayed in statute and was narrowed rather than removed, so that from 1 January 2026 it applies where the junior unit has shared sanitation with the existing structure.
That asymmetry rules the junior ADU out for an investor entirely, and for any owner who might move. It also interacts awkwardly with the shared-bathroom allowance: the feature that makes a JADU cheap to build is the feature that triggers the condition.
What would settle it. The 1 January 2026 narrowing is a natural experiment.
If junior permits rise materially after that date in jurisdictions where the shared-sanitation carve-out bites, that is evidence for this explanation. The permit data will support that test in a couple of years.
It does not support it yet, and our frame extends only to 2026-08-30.
3. A unit with no separate envelope is a harder financing case
An ADU financing product generally underwrites the completed value of a distinct structure or the rent it will produce. A junior ADU adds neither a separate building nor a separately sellable asset — and it cannot be sold separately at all, because the required deed restriction prohibits it.
HyreADU analysis, not a lender survey. We have not interviewed lenders about junior ADU underwriting and do not claim to know how any particular product treats one. Our financing study sets out how narrow the ADU product set already is.
4. Five hundred square feet is a small unit, and that is the definition
The statutory ceiling is 500 square feet of interior livable space against a state-law floor of 850 for an ordinary ADU. A junior unit is at most a studio or a very small one-bedroom. On the Los Angeles record the median JADU-flagged permit is 44.5% of the median new-construction ADU permit.
That is genuinely useful for an adult child, an ageing parent or a lodger, and genuinely unsuitable for others. The size limit is not a flaw; it is the definition. But it does mean the category competes for a narrower set of household situations, which alone would produce a smaller number.
None of the four is measured here. They are labeled analysis because that is what they are. The two things this page measures are a share and a duration, and both are Los Angeles.
Every figure on this page, with its class
The full ledger, so the 25-of-41 split can be checked rather than taken on trust. Nothing appears anywhere on this page that is not in this table.
| Statistic | Figure | Geography | Date | Class | Source |
|---|---|---|---|---|---|
| Maximum size of a junior ADU | 500 sq ft of interior livable space | California | In force 2026 | Agency published | Gov. Code § 66313(d), leginfo, 2026-09-05 |
| Where a junior ADU may be located | Contained entirely within, and constructed within the walls of, a single-family residence | California | In force 2026 | Agency published | Gov. Code § 66313(d), leginfo, 2026-09-05; § 66333(d) |
| Junior ADUs permitted per residential lot | 1 | California | In force 2026 | Agency published | Gov. Code § 66333, leginfo, re-verified 2026-09-07 |
| Separate exterior entrance required | Yes | California | In force 2026 | Agency published | Gov. Code § 66333(e), 2026-09-07 |
| Kitchen required | An efficiency kitchen — cooking appliance, food preparation counter, storage cabinets | California | In force 2026 | Agency published | Gov. Code § 66333(f), 2026-09-07 |
| Bathroom | May be shared with the single-family residence | California | In force 2026 | Agency published | Gov. Code § 66333, leginfo, re-verified 2026-09-07 |
| Owner-occupancy condition | Required only where the JADU has shared sanitation facilities with the existing structure | California | From 1 Jan 2026 | Agency published | Gov. Code § 66333(b) as amended by AB 1154 (Stats. 2025, Ch. 507), 2026-09-07 |
| Owner-occupancy exception | Where the owner is a governmental agency, land trust or housing organization | California | From 1 Jan 2026 | Agency published | Gov. Code § 66333(b), 2026-09-07 |
| Recorded deed restriction required | Yes — prohibits sale separate from the single-family residence | California | In force 2026 | Agency published | Gov. Code § 66333(c), 2026-09-07 |
| Decision deadline for a junior ADU application | 60 days, ministerial | California | In force 2026 | Agency published | Gov. Code § 66335, 2026-09-07 |
| Off-street parking a city may require for a junior ADU | None | California | In force 2026 | Agency published | Gov. Code § 66334, 2026-09-07 |
| Treatment for utility connection and capacity fees | Not a new residential use — no new or separate connection fee | California | In force 2026 | Agency published | Gov. Code § 66338, 2026-09-07 |
| Treatment for fire and life protection purposes | Not a separate or new dwelling unit | California | In force 2026 | Agency published | Gov. Code § 66337, 2026-09-07 |
| Owner-occupancy requirement for an ordinary ADU | Prohibited | California | In force 2026 | Agency published | Gov. Code § 66315, 2026-09-05 |
| Smallest maximum size a city may impose on an ordinary ADU | 850 sq ft (1,000 with multiple bedrooms) | California | In force 2026 | Agency published | Gov. Code § 66321(b)(2), 2026-09-05 |
| Statewide junior ADU count published by any agency | None — Table A2 has no JADU unit category | California | 2026-09-05 | Agency published | HCD Housing Element Annual Progress Report, Table A2 field list |
| ADU-adding permits in the Los Angeles analysis frame | 39,278 | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| JADU-flagged permits | 3,778 | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · junior ADU study |
| JADU share of ADU permits | 9.62% | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · junior ADU study |
| Standard ADU permits | 35,500 (90.38%) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · junior ADU study |
| Occupancy events observed, junior ADUs | 2,447 | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Occupancy events observed, standard ADUs | 22,525 | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Median permit-to-occupancy, junior ADU | 387 days | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Median permit-to-occupancy, standard ADU | 509 days | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Median advantage, junior over standard | 122 days faster | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| 25th percentile permit-to-occupancy, junior vs standard | 212 days vs 301 days (89 faster) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| 75th percentile permit-to-occupancy, junior vs standard | 908 days vs 1,086 days (178 faster) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Median advantage against the whole ADU frame | 112 days faster than 499 days | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Reaching occupancy within 1 year, junior vs standard | 47.3% vs 34.0% (+13.3 points) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Reaching occupancy within 18 months, junior vs standard | 63.2% vs 53.4% (+9.9 points) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Reaching occupancy within 2 years, junior vs standard | 70.3% vs 64.5% (+5.8 points) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| Reaching occupancy within 3 years, junior vs standard | 78.4% vs 75.1% (+3.2 points) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · construction duration study |
| JADU-flagged permits carrying a usable floor-area value | 2,238 | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| Median permitted floor area, JADU-flagged permits | 409 sq ft | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| Interquartile range, JADU-flagged floor area | 353 sq ft – 499 sq ft | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| 90th percentile, JADU-flagged floor area | 1,378 sq ft | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| JADU-flagged permits at or under the 500 sq ft statutory ceiling | 76.05% | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| JADU-flagged permits above the 500 sq ft ceiling on the LADBS field | 23.95% | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| Median JADU floor area as a share of the statutory ceiling | 81.8% | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| Median JADU floor area against median new-construction ADU floor area | 409 sq ft vs 920 sq ft (44.5%) | City of Los Angeles | 2020 – 2026-08-30 | HyreADU calculation | LADBS resource pi9x-tg5x, rows updated 2026-08-31 · size distribution study |
| Statewide JADU count published by HyreADU | None — the state file cannot support one | California | 2026-09-05 | HyreADU calculation | HCD Housing Element Annual Progress Report, Table A2 field list · junior ADU study |
25 HyreADU calculation · 16 Agency published · 0 Trade / survey estimate. The hub gate requires at least one third to be ours; this page is at 61 per cent.
Junior ADU figures we will not repeat
- A California or national junior ADU count
HCD’s Table A2 has no JADU unit category, so junior units are indistinguishable in the state file from ordinary ADUs wherever a jurisdiction coded them that way.
There is no federal instrument with an accessory category at all. Any statewide or national JADU total in circulation was constructed rather than measured, and it should be traced before it is used.
- A junior ADU cost figure
We hold no JADU-specific cost dataset. It is widely and plausibly stated that a junior unit is cheaper than an ADU — a smaller unit, an efficiency kitchen, a possibly shared bathroom — but we have not measured it and we publish no figure.
The cost study covers what we can source, and the declared permit valuation on a permit is a fee input rather than a construction cost.
- “Owner-occupancy is required for every junior ADU”
Stale since 1 January 2026. Section 66333(b), as amended by AB 1154 (Stats. 2025, Ch. 507), requires it only where the junior unit has shared sanitation facilities with the existing structure, with an exception where the owner is a governmental agency, land trust or housing organization.
A great deal of published guidance, including some local pages, still describes the blanket rule.
- Section 65852.22 as the citation
Repealed by SB 477 (Stats. 2024, Ch. 7) with effect from 25 March 2024. The junior ADU provisions now sit at Government Code sections 66333 to 66339.5, with the definition at section 66313(d). A regulatory page citing the repealed section is describing a document that no longer exists.
- Our Los Angeles share or duration quoted as a California figure
9.6%, 387 days and 76.0% are the City of Los Angeles, from the city’s own permit file. We hold no comparable extract for any other jurisdiction and publish no state version of any of them.
Citing these figures
Journalists and planning desks are welcome to cite these tables. Link the junior ADU study rather than this digest where you need the method and the limits.
Where a figure is labeled HyreADU calculation, attribute it to HyreADU and name the file — “HyreADU analysis of City of Los Angeles LADBS building permit data, resource pi9x-tg5x, rows updated 2026-08-31”.
Where it is Agency published, cite the Government Code section by its current number. Corrections go on the page with a dated note: hello@hyreadu.com.
If you take one number from this page, take the one with the caveat attached: 9.6% of Los Angeles ADU permits are junior units, and the flag that produces that figure disagrees with the statutory size ceiling on about a quarter of the permits we can measure.
A share worth quoting is a share whose classifier you have looked at.
Questions
What is a junior ADU?
What is the difference between a JADU and an ADU?
How many junior ADUs are built in California?
Do I have to live in the house to have a junior ADU?
Are junior ADUs quicker to build?
How big is a typical junior ADU?
Can a junior ADU be in the garage?
Do I need parking for a junior ADU?
Can I have both an ADU and a junior ADU on the same lot?
Can a junior ADU be sold separately?
Written and audited by
HyreADU Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a builder. We read the permit extract, the statute, the HCD return or the fee schedule ourselves, and publish each figure with its source and retrieval date.
Where a number cannot be traced to a primary source, we leave it out and say what we could not verify. Our store-based claims cover California only.
- CA
- the only state this desk will make store-based claims about
- 5
- jurisdictions with extracted ADU permit evidence
- 735
- CSLB-verified companies in the California store
- 0
- national claims from a one-state store
How this desk works
- Primary sources only. Permit counts come from the city or county that issued the permit. Production counts come from HCD’s Annual Progress Report. Rents come from HUD or the Census. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
- This is a California site. The company store is 734 California firms and one New Mexico firm. Permit evidence exists for five named jurisdictions: Los Angeles, San Francisco, Sacramento, San José and unincorporated Marin. A number from that store is titled to those places, never to the United States.
- A permit is not a completion, and a license is not an ADU grade. California licenses no ADU classification. Being named on an ADU permit is evidence of engagement in that jurisdiction, not of quality, completion, or work anywhere else. Owner-builder permits are excluded from contractor counts.
- Calculation is labeled as calculation. Figures we derive are never presented as something HCD, HUD, the Census or a city published. Terner Center research is cited as Terner’s, never restated as ours.
- We do not design, permit or build ADUs, and we take no payment for placement, ranking or a favorable mention. Pages that look like rankings are not: they publish public-record counts and let the reader decide.
- Nothing here is legal, tax or financial advice. Zoning, underwriting and appraisal practice vary by jurisdiction, lender and appraiser. The useful next step on a specific lot is the planning counter and a licensed professional.
Data as of LADBS building permit extract (data.lacity.org resource pi9x-tg5x), rows updated 2026-08-31; Government Code Chapter 13 retrieved from leginfo 2026-09-05 and § 66333 re-verified 2026-09-07. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold.
Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
- California Government Code § 66333 — junior accessory dwelling unit ordinance requirements , Retrieved 2026-09-05 and re-verified 2026-09-07. (a) one junior unit per residential lot zoned for single-family residences; (b) owner-occupancy required “[i]f the junior accessory dwelling unit has shared sanitation facilities with the existing structure”, with an exception where the owner is a governmental agency, land trust or housing organization; (c) a recorded deed restriction running with the land, prohibiting sale separate from the single-family residence; (d) “constructed within the walls of the proposed or existing single-family residence”; (e) a separate entrance from the main entrance to the residence; (f) an efficiency kitchen with a cooking facility, a food preparation counter and storage cabinets. Enactment line: “Amended by Stats. 2025, Ch. 507, Sec. 1. (AB 1154) Effective January 1, 2026.” Retrieved 2026-09-07.
- California Government Code § 66313 — definitions , Retrieved 2026-09-05. Subdivision (d), verbatim: a junior accessory dwelling unit is “a unit that is no more than 500 square feet of interior livable space in size and contained entirely within a single-family residence.” Subdivision (a) defines the accessory dwelling unit; subdivision (e) defines livable space. Amended by SB 543 (Stats. 2025, Ch. 520), operative 1 January 2026. Retrieved 2026-09-05.
- California Government Code, Title 7, Division 1, Chapter 13, Article 3 — junior accessory dwelling units (§§ 66333–66339.5) , Re-verified 2026-09-07. § 66334 no additional parking may be required; § 66335 ministerial approval within 60 days; § 66336 a permit may not be denied because of an existing code violation on the property; § 66337 a junior unit is not a separate or new dwelling unit for fire or life protection purposes; § 66338 a junior unit is not a new residential use for utility connection fee or capacity charge purposes; § 66339 and § 66339.5 apply where no local ordinance exists. Article created by SB 477 (Stats. 2024, Ch. 7); amended by AB 1154 (Stats. 2025, Ch. 507) and SB 543 (Stats. 2025, Ch. 520). Former Government Code § 65852.22 was repealed by SB 477 in March 2024. Retrieved 2026-09-07.
- AB 1154 (Carrillo, 2025) — junior accessory dwelling units. Stats. 2025, Ch. 507 , Chaptered 10 October 2025, operative 1 January 2026. Amends § 66333 so that owner-occupancy is required only where the junior unit has shared sanitation facilities with the existing structure, with an exception where the owner is a governmental agency, land trust or housing organization. Retrieved 2026-09-05.
- California Government Code § 66315 — no owner-occupant requirement for an ADU , The provision that prohibits a local owner-occupancy requirement for an ordinary accessory dwelling unit, and therefore the source of the ADU/JADU asymmetry that runs through this page. Added by Stats. 2024, Ch. 7, Sec. 20 (SB 477). Retrieved 2026-09-05.
- City of Los Angeles Department of Building and Safety — Building Permits Issued from 2020 to Present , Open data resource pi9x-tg5x on data.lacity.org. Rows updated 2026-08-31; 409,619 rows downloaded. 41,374 ADU-flagged rows, 2,095 supplementals excluded, 39,278 analyzed, of which 3,778 JADU-flagged and 35,500 standard ADU. Permit-to-occupancy durations computed from permit issue to certificate of occupancy or final. All counts, shares, percentiles and floor-area statistics attributed to this source are HyreADU calculations from the raw extract, not figures published by the City. Retrieved 2026-08-31.
- California Department of Housing and Community Development, Housing Element Annual Progress Report — Table A2 , Cited here for a negative finding that matters: Table A2 has no separate junior ADU unit category, and junior accessory dwelling units appear in the file only where the jurisdiction coded them as UNIT_CAT = ADU. There is therefore no statewide junior ADU count derivable from the state dataset. Retrieved 2026-09-05.
- City of Long Beach, Community Development — Accessory Dwelling Units , Source of the local nuance cited on this page: junior ADU owner-occupancy is required in Long Beach only if the junior unit shares a bathroom with the main home. The same page states that Long Beach Municipal Code 21.51.276 no longer applies and that the city currently applies state ADU law directly. Retrieved 2026-09-05.
The smallest, quickest legal route to a second unit is also the least used
If a junior ADU fits your house and your circumstances, the constraints that keep the category small may not apply to you. The size and envelope calculator is a place to start; it will never tell you that you can build.
HyreADU does not design, permit or build accessory dwelling units, and does not practice law. This page is informational and is not legal advice and not a feasibility opinion on any property.
Statutory text is quoted as retrieved on 5 September 2026, with section 66333 re-verified on 7 September 2026; California’s ADU chapter has been recodified twice since March 2024 and the junior ADU sections were among those moved.
Permit counts, shares, durations and floor areas are HyreADU calculations from a City of Los Angeles open dataset extracted on 2026-08-31 — they are figures about that city only, they are not figures published by the City, and they rest on the department’s administrative junior-ADU flag rather than on a statutory determination.
Where that flag disagrees with the statutory size ceiling, we report the disagreement and reach no conclusion about the compliance of any permit. No statewide junior ADU count is published, because the state dataset contains no junior ADU category.
Converting interior space to create a dwelling involves structural, electrical, plumbing and fire-safety work that must be carried out under permit by licensed professionals.