Statistics

ADU statistics

Q: What do the three provenance labels mean?

HyreADU calculation means we downloaded a primary file and computed the figure ourselves. Agency published means HCD, HUD, the Census, a city or CSLB printed the number and we cite their table rather than an article about it. Trade estimate means a builder survey, a cost index or an owner survey: useful, labeled, and never presented as a measurement of every ADU in California.

Every figure traced to the file it came from, with the date we retrieved it — and a note on the ones that cannot be traced anywhere.

Updated September 2026 · Data as of September 2026

Written by HyreADU Research Desk Primary-source research and data analysis

≥⅓ of figures on any digest must be HyreADU calculations Below that, we publish the study instead

CA geography of every store-based figure National claims rest on HUD, Census or statute

3 provenance classes, printed on every row Ours · agency published · trade estimate

How to use this page

These pages are digests of figures the HyreADU Research Desk has already computed in a full study, plus the federal and state numbers those studies rest on.

Each figure is labeled as a HyreADU calculation, an agency-published statistic, or a trade estimate, and each links back to the study that produced it.

A statistics page here ships only when at least a third of its figures are ours. Nothing on these pages is a national ADU statistic derived from our one-state company store.

The statewide anchor

Start here. These three set the geography of every other figure on the site.

Anchor 48 of 68 figures ours ADU statistics The statewide anchor: permits, completions, the gap between them, and which figures in the California record are measurements rather than estimates. Read the page 27.8% LA share of CA permits California ADU statistics The jurisdiction view. Los Angeles alone is 27.76% of all California ADU permits and the top 20 cities are 51.99% — plus how good each reporter’s file actually is. Read the page Non-CA No California figure extrapolated ADU statistics outside California What can be said about ADUs beyond California without scaling a Californian number: Seattle’s published series, six retrieved state statutes, and Census permit methodology. Read the page

Cost, fees and money

Cost 57% ours ADU cost statistics What the record shows an ADU costs, separated from what the trade says it costs — every figure carrying its source and the date we pulled it. Read the page Fees From the fee study ADU fee statistics Impact, permit and plan-check fees from the city-by-city study, with the statutory proportional-fee ladder worked as arithmetic. Read the page Finance Two labeled readings ADU financing statistics The 30% ADU-income cap derived two ways, because the agency’s own worked example does not close. Both readings published with their binding rent thresholds. Read the page Tax 59% ours ADU property tax statistics How an ADU is assessed: the blended-rate arithmetic on the added value only, not a reassessment of the whole parcel. Read the page Value What would have to be true ADU property value statistics Cost-to-home-value ratios, and an inversion confined to Los Angeles. No value-add percentage on this page is ours — the coefficient does not travel to a statewide median. Read the page 89% ours Declared valuation ≠ cost ADU permit valuation statistics Declared permit valuation is not construction cost. This is the distribution, the indexing factor, and the gap between the two. Read the page

Permits, approval and the clock

Permits 54% ours ADU permit statistics The permit record itself: volume, type split, and the reporting holes that qualify every count drawn from it. Read the page 581→322 SF approval days ADU approval time statistics Days from application to issuance by city. San Francisco fell from 581 days on 2022 issuances to 322 on 2025. Read the page Build 72% ours ADU construction time statistics Issuance to final, from the Los Angeles duration file — the half of the clock the approval figures never cover. Read the page Supply 56% ours ADU housing supply statistics ADUs against RHNA need: what share of the housing requirement this form is actually carrying. Read the page

Law, zoning and compliance

3 of 7 statutes with no trigger ADU legalization statistics Six-lever verification across four states, a seven-statute ministerial fingerprint, and a recodification concordance built from the code’s own renumbering lines. Read the page 29.9% R1-1 share ADU zoning statistics The first published zone-district composition of a large ADU frame: R1-1 alone is 29.86%, single-family zones outnumber multi-family 6.2 to 1. Read the page 73.0% categorically exempt ADU parking statistics Which exemption actually carries the load: 72.98% of LA ADU permits are alterations or additions, parking-exempt with no map and no measurement. Read the page 24.0% above the JADU ceiling Junior ADU statistics The size distribution the JADU study omitted — 23.95% of JADU-flagged permits sit above the 500 sq ft ceiling. Both explanations published, no compliance conclusion drawn. Read the page Estimates labeled as estimates Unpermitted ADU statistics Every HyreADU figure here measures the permitted record. The unpermitted numbers are other people’s estimates, labeled, with their denominators printed. Read the page

The units themselves

81% ours Size distribution ADU size statistics Floor-area distribution against the statutory caps, from the Los Angeles permit file. Read the page 60.6→44.6% garage share of permits Garage conversion statistics The conversion share of the ADU record and how fast it is falling: 60.6% to 44.6% between 2020 and 2025. Read the page 1,369 sq ft vs a 1,200 cap Prefab and modular ADU statistics No agency counts prefab ADUs, so this rests on the Census Manufactured Housing Survey: the average West-region HUD-Code home is 1,369 sq ft — 169 above California’s detached cap. Read the page 76.5% presently able to contract ADU builder statistics The licensed population that builds them: 964 licenses, 735 store files, and the 23.5% not presently able to contract. No company is named. Read the page 67.5% above the 750 sq ft waiver line ADU utility connection statistics Ships with no connection-fee dollars, deliberately — no adopted schedule was retrievable. The statutory fee ladder is worked instead, against LA floor areas. Read the page 2.54× statewide growth ADU occupancy statistics Who lives in them, and the geography shift underneath: LA falls 75.0% to 55.6% of the frame while San Diego rises 5.2% to 16.8%. Read the page

Rent

Rents From the rental-income study ADU rental income statistics Rent bands by California market from HUD FMR and ACS gross rent, with Terner’s family-occupancy correction applied so a yield figure does not assume every ADU is let at market. Read the page

The provenance split

Almost every ADU statistics roundup on the web is a chain of citation that terminates in a builder’s brochure. This hub’s spine is therefore provenance, not volume.

HyreADU calculation — we downloaded a primary file and computed the figure. The method lives on the study page.

Agency published — HCD, HUD, the Census, a city or CSLB printed this number. We cite the table, not an article about the table.

Trade estimate — a builder survey, a cost index, or Terner’s owner survey. Useful, labeled as what it is, never presented as a measurement of every ADU in California.

What is still missing

The fee and cost digests promised in the first version of this hub are now live, each cut from its own study rather than from other people’s per-square-foot claims.

What is still absent is deliberate. There is no national ADU cost figure here, because our company store is one state and a national claim cannot be built from it.

There is no unpermitted-stock count of our own, because the permitted record is the only thing we can measure.

And there is no value-add percentage of our own, because the published coefficient does not survive being applied to a statewide median.

Every digest prints a figure ledger. If a number on this site is not ours, the ledger says whose it is.

Questions

Where do these ADU statistics come from?

Each figure is traced to the file it came from: municipal building-permit open data, HCD’s Housing Element Annual Progress Report, HUD Fair Market Rents, Census tables, or the California Contractors State License Board. Figures the desk computed itself link back to the study that shows the method.

What do the three provenance labels mean?

HyreADU calculation means we downloaded a primary file and computed the figure ourselves. Agency published means HCD, HUD, the Census, a city or CSLB printed the number and we cite their table rather than an article about it. Trade estimate means a builder survey, a cost index or an owner survey: useful, labeled, and never presented as a measurement of every ADU in California.

How often are these figures updated?

Every digest carries a published date, a data-as-of line, and a retrieval date on each source. Digests are re-cut when the study behind them is re-cut, which for the annual state figures means when HCD releases the next Annual Progress Report.

Can I cite or republish these numbers?

Yes, with a link back to the digest or the study. The provenance label and the limitations live on the page, and a figure quoted without them is easy to misread.

Is there a national ADU statistic on this site?

Not one derived from the HyreADU company store, which covers one state. Where a figure reaches beyond California it rests on a federal source such as HUD Fair Market Rents or the Census, and the page says which.

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 September 2026. 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.

A statistic is not a rent roll

Fair Market Rent is a policy construct. What a specific ADU lets for is a street, a finish level and a lease.

Rent estimator Read the studies

HyreADU does not design, permit or build accessory dwelling units. Statistics are informational. They are not legal, tax, financial or construction advice.