Statistics
ADU permit valuation statistics
105 of 118 figures are HyreADU calculations. The most available ADU dollar figure in California, distributed by year, by permit type, by size, by planning area and by city — and measured against what it is routinely mistaken for.
Written by HyreADU Research Desk Primary-source research and data analysis
Audited by HyreADU Research Desk Cost-label discipline and indexation audit
How to use this page
A declared permit valuation is not a construction cost and it is not a market price. It is a figure an applicant writes on a building-permit application, it is the input to the plan-check and permit fee in most California fee schedules, and some cities replace it outright with a published dollar-per-square-foot table.
That is the whole page: the number is real, it is public, it is the easiest ADU cost proxy in California to obtain — and it measures something other than cost.
The size of the gap, measured. On 8,528 new detached ADU building permits in the City of Los Angeles, the median declared valuation is $120/sf, with the middle half between $102/sf and $152/sf.
Carrying the 2021 California owner survey forward on the DGS construction-cost index to August 2026 puts a detached unit at $461/sf. The declared median is about 26% of that, and even the 90th percentile of declared rates, at $201/sf, reaches only 44%.
A cost figure built from permit valuations is low by roughly a factor of 3.8. The number also varies between cities more than construction plausibly does. Across five jurisdictions the median declared valuation on an ADU permit runs from $40,000 to $156,800 — a spread of about 3.9× under one statewide statute.
Some of that is genuine. Much of it is valuation practice, and San José’s hard ceiling at exactly $234,848 is the clearest tell.
None of this is an accusation. Under-declaration is a systematic property of how building-permit fees are assessed everywhere in the United States that assesses them that way; applicants frequently declare exactly what a city instruction or a city table tells them to; and this page names no permit, no applicant and no contractor.
What it does is put a number on a bias every researcher who reaches for permit data inherits. 105 of 118 figures on this page are HyreADU calculations (105 hyreadu calculation, 10 agency published, 3 trade / survey estimate). Not a cost estimate, not a budget, not advice.
What a declared valuation actually is
When an applicant files for a building permit, one of the fields is the value of the proposed construction. That figure does two jobs at once.
It becomes part of the permanent public record of the permit, and — in most California fee schedules — it becomes the input to the plan-check and permit fee the applicant is about to pay.
Those two jobs point in opposite directions. A record wants an accurate number. A fee basis creates a reason for the number to be low. The result is a field that is systematically pulled downward, and that pull is a property of the instrument, not of the people filling it in.
Some cities remove the applicant’s discretion entirely. Sacramento publishes a residential valuation table on form CDD-0245 that sets new living area at $170.80 per square foot and a garage conversion at $101.16; San José points applicants at ICC construction-tax valuation rates.
Where a table governs, the “valuation” field stops being an estimate of anything and becomes an arithmetic output of floor area — which is why San José’s harvest has a maximum of exactly $234,848 against a 90th percentile of $167,433, a ratio of just 1.40 to one. Real markets have longer tails than that.
And the scope is narrower than a homeowner’s idea of cost. Design and engineering, the plan-check and permit fees themselves, school, park and traffic impact fees, utility connection and capacity charges, site work outside the permitted structure, financing costs and the contractor’s margin are all things a household pays for an ADU, and none of them is what the valuation field asked about.
HyreADU analysis. Put those three effects together — a downward fee incentive, a table that flattens, and a narrower scope — and you would predict a declared valuation well under half of a household’s total outlay.
The measured ratio in Los Angeles, 26% of an indexed detached-unit cost, is at the low end of even that expectation.
The figures most worth knowing
Full method, exclusions and limits on the permit-valuation study. Nothing here is a cost estimate for any project.
The whole Los Angeles distribution
The frame is 39,279 non-supplemental permits from the City of Los Angeles open-data extract, flagged by the department’s own ADU or junior-ADU fields, issued in 2020 or later.
Below is the declared valuation across all of them, and then split on the department’s permit type — which is the closest available proxy for what kind of unit was built.
Levels, not rates: the floor areas differ and so does the scope of work.
| Cut | n (> $0) | p10 | p25 | Median | p75 | p90 | Mean | Class |
|---|---|---|---|---|---|---|---|---|
| All ADU permits | 39,250 | $20,000 | $35,000 | $60,000 | $118,894 | $192,065 | $100,106 | HyreADU calculation |
| New construction (detached ADU) | 10,604 | $60,000 | $90,000 | $124,661 | $200,000 | $350,000 | $189,274 | HyreADU calculation |
| Addition (attached ADU) | 12,224 | $33,180 | $50,000 | $75,000 | $115,000 | $175,195 | $100,980 | HyreADU calculation |
| Alteration or repair (largely conversions) | 16,421 | $15,000 | $20,000 | $32,000 | $50,000 | $75,000 | $41,880 | HyreADU calculation |
| Garage conversions (department flag) | 19,286 | $20,000 | $30,000 | $48,000 | $75,000 | $102,457 | $59,525 | HyreADU calculation |
| Non-garage units | 19,964 | $20,000 | $47,000 | $96,000 | $150,000 | $272,000 | $139,309 | HyreADU calculation |
HyreADU calculation on LADBS resource pi9x-tg5x on data.lacity.org, 409,619 rows downloaded, refreshed 2026-08-30, retrieved 2026-09-05. Frame: adu_changed > 0 OR junior_adu = 1; supplemental permits dropped by permit-number middle segment; issue year 2020 or later.
Only 29 permits in the frame carry a zero or blank valuation, so the distribution is not being shaped by missing data. Declared permit valuation, not construction cost.
Two things to notice about the shape. The mean across all ADU permits, $100,106, sits between the 75th and 90th percentiles — the signature of a long right tail, and the reason every headline figure on this page is a median rather than an average.
And the permit-type split is doing enormous work: alterations and repairs, which are largely conversions, have a median of $32,000 against $124,661 for new construction.
Anyone quoting a single citywide median for “what an ADU costs in Los Angeles” is quoting a weighted average of two quite different products, computed on the wrong instrument.
What the declared number has done since 2020
Nominal dollars, by year of issue. The two series are the whole ADU frame and the new-construction subset, and they have moved differently: the citywide median rose 116% from 2020 to the 2026 part year, while the new-detached median rose 23%.
The 90th percentile on new construction moved far more — 233% — which is a widening tail rather than a rising center.
| Year of issue | Permits in the frame | Median, all ADU permits | Median, new detached | p90, new detached | Class |
|---|---|---|---|---|---|
| 2020 | 3,373 | $37,000 | $108,500 | $150,000 | HyreADU calculation |
| 2021 | 5,072 | $45,000 | $116,000 | $180,000 | HyreADU calculation |
| 2022 | 7,120 | $60,000 | $120,000 | $280,000 | HyreADU calculation |
| 2023 | 6,158 | $65,000 | $123,450 | $380,000 | HyreADU calculation |
| 2024 | 6,394 | $70,000 | $121,000 | $400,000 | HyreADU calculation |
| 2025 | 6,933 | $75,000 | $125,000 | $400,000 | HyreADU calculation |
| 2026 (part year) | 4,229 | $80,000 | $133,000 | $500,000 | HyreADU calculation |
HyreADU calculation on LADBS resource pi9x-tg5x on data.lacity.org, 409,619 rows downloaded, refreshed 2026-08-30, retrieved 2026-09-05. Nominal dollars, not deflated. The 2026 row covers permits issued to 2026-08-30 and is not comparable to a full year on volume.
Resist reading this series as construction inflation, and here is why. Over roughly the same window the DGS California Construction Cost Index rose by a factor of 1.536, or about 54%.
The new-detached declared median rose 23%. Those two numbers are close enough to tempt a causal reading, and the temptation should be resisted: a declared valuation can move because construction is dearer, because the size mix shifted, because a city changed its instruction or its table, or because applicants adjusted what they write. The series cannot distinguish those, and neither can we.
The gap, per square foot
Dividing declared valuation by the floor area recorded on the same permit removes the size difference between a 480-square-foot conversion and a 1,194-square-foot detached unit, and leaves a rate that can be set beside a construction-cost rate.
This is the measurement the whole page turns on, and it is available only for Los Angeles, because it is the only one of the five jurisdictions publishing a departmental ADU flag and a floor-area field on the same complete extract.
| Measure | Value | What kind of number it is | Class | Source |
|---|---|---|---|---|
| Declared valuation per square foot — 10th percentile | $96/sf | A fee input recorded on a permit | HyreADU calculation | LADBS pi9x-tg5x, 8,528 new detached ADU permits |
| Declared valuation per square foot — 25th percentile | $102/sf | A fee input recorded on a permit | HyreADU calculation | LADBS pi9x-tg5x, 8,528 new detached ADU permits |
| Declared valuation per square foot — median | $120/sf | A fee input recorded on a permit | HyreADU calculation | LADBS pi9x-tg5x, 8,528 new detached ADU permits |
| Declared valuation per square foot — 75th percentile | $152/sf | A fee input recorded on a permit | HyreADU calculation | LADBS pi9x-tg5x, 8,528 new detached ADU permits |
| Declared valuation per square foot — 90th percentile | $201/sf | A fee input recorded on a permit | HyreADU calculation | LADBS pi9x-tg5x, 8,528 new detached ADU permits |
| Indexed cost per square foot — garage conversion | $291/sf | Somebody else’s 2018–19 survey, indexed by us | HyreADU calculation | Survey $189/sf × 1.536 |
| Indexed cost per square foot — statewide, all types | $384/sf | Somebody else’s 2018–19 survey, indexed by us | HyreADU calculation | Survey $250/sf × 1.536 |
| Indexed cost per square foot — detached | $461/sf | Somebody else’s 2018–19 survey, indexed by us | HyreADU calculation | Survey $300/sf × 1.536 |
| Ratio: median declared ÷ indexed detached | 26% | A comparison of two independent instruments | HyreADU calculation | The finding of this page |
| Ratio: 90th-percentile declared ÷ indexed detached | 44% | A comparison of two independent instruments | HyreADU calculation | $201/sf ÷ $461/sf |
| Ratio: median declared ÷ indexed garage conversion | 41% | A comparison of two independent instruments | HyreADU calculation | $120/sf ÷ $291/sf |
| Implied understatement factor | 3.8× | What a cost analysis built on permit valuation would be out by | HyreADU calculation | $461/sf ÷ $120/sf |
HyreADU calculation. The indexation chain: DGS California Construction Cost Index, December 2019 = 6,924, August 2026 = 10,633, factor 1.535673, applied to Chapple, Ganetsos and Lopez’s 2021 medians. DGS’s own caution travels with it: the index “does not reflect current market bidding environment.”
The choice of index is not driving the result. The Census and HUD constant-quality Laspeyres price index of new single-family houses under construction gives a factor of 1.487 over a comparable period, against the DGS factor of 1.536 — close enough that swapping one for the other would move the ratio by a few percentage points, not by an order of magnitude.
That national index is published here only as that check; it is not California and it is not ADU-specific.
How much of the gap is scope, and how much is the instrument
Scope against instrument is the question that decides whether the finding is honest, so it gets its own section rather than a footnote. Comparing a declared valuation to an owner-reported total cost is comparing two different scopes, and part of the four-to-one gap is definitional rather than behavioural.
A permit valuation is, at best, the value of the permitted construction work.
The 2021 survey’s cost figure was explicitly “the total cost that the homeowner spent on their ADU, and is inclusive of all costs for design, labor, materials, and permits.” Design and engineering, plan-check and permit fees, impact fees where they apply, utility connection charges, site work outside the permitted structure, financing costs and the contractor’s margin are inside one number and outside the other.
So the defensible claim is about the ratio, not about anybody’s honesty. Two independent instruments, measured on the same units in the same city, differ by roughly four to one in exactly the direction the mechanism predicts.
That is a bound on how far a permit-derived cost figure can be trusted. It is not a decomposition into “this much scope, that much under-declaration,” and we do not have the data to produce one.
What can be said with more confidence is the direction and the size of the error a researcher inherits. Because permit valuation is the most accessible ADU dollar figure in California — free, public, machine-readable, and available in bulk when fee schedules are not — it is what a great deal of analysis reaches for.
A study that computes “average ADU cost in Los Angeles” from the permit file and reports it as a cost is out by something like a factor of 3.8. That is not a rounding error.
It is the difference between a number that supports a policy argument and one that destroys it, and it is why this page exists.
And it should be said plainly that nobody is being accused of anything. Under-declaration is a known and systematic feature of permit valuation everywhere in the United States that assesses fees this way.
Applicants frequently declare exactly what a city instruction or a city valuation table tells them to declare — Sacramento’s and San José’s tables are published, and following them is compliance, not evasion.
This page names no permit, no applicant and no contractor in connection with any declared figure.
The floor areas underneath the rates
The per-square-foot rate is only meaningful because the extract records a floor area on the same permit. Those areas are worth publishing in their own right, because they show where Los Angeles ADU production actually clusters — and it is not where the fee statute would push it.
| Measure | Value | Class | What it says |
|---|---|---|---|
| Median recorded floor area, new-construction permits | 920 sq ft | HyreADU calculation | Interquartile range 670 to 1,194 sq ft; n = 8,536. |
| 10th and 90th percentiles | 460 and 1,343 sq ft | HyreADU calculation | A wide distribution: the smallest tenth are studio-scale, the largest tenth are the size of a small house. |
| Share at 500 sq ft or less | 14.2% | HyreADU calculation | Inside the junior-ADU threshold and inside the school-fee assessable-space test. |
| Share at 750 sq ft or less | 32.5% | HyreADU calculation | Inside the statutory impact-fee bar at Government Code § 66311.5(c)(1). About two-thirds of new-construction permits are not. |
| Share between 1,100 and 1,200 sq ft | 26.0% | HyreADU calculation | A pronounced cluster at the top of the local size envelope, well above the fee threshold. |
| Permits recorded between 1,195 and 1,200 sq ft | 1,061 | HyreADU calculation | Of which 635 are recorded at exactly 1,200 — the signature of a ceiling being built to. |
HyreADU calculation on LADBS resource pi9x-tg5x on data.lacity.org, 409,619 rows downloaded, refreshed 2026-08-30, retrieved 2026-09-05, new-construction ADU permits with a floor area in range (838 of 9,374 dropped as out of range). Recorded floor area is the department’s field and is not necessarily interior livable space, which is the measure the fee statute uses.
A finding worth stating carefully. Only 32.5% of new-construction ADU permits are at or below 750 square feet, and 26.0% sit in the 1,100–1,200 band, with 635 recorded at exactly 1,200.
The impact-fee cliff at 750 square feet is real and is documented on the fee digest — but in this city, on this permit field, the cluster is at the top of the size envelope, not at the fee threshold.
That is a genuinely interesting result, and it has an obvious caveat: the field here is recorded floor area, not the interior livable space the statute measures, so the two thresholds are not being compared on the same ruler.
Conversions and new units are two different populations
The department flags garage conversions, and they are 49.1% of the Los Angeles ADU frame — a share large enough that any citywide median is really a weighted blend of two products. Splitting on that flag separates them.
| Measure | Garage conversions | Non-garage units | Ratio | Class |
|---|---|---|---|---|
| Permits in the frame | 19,294 | 19,985 | 49.1% of the frame are conversions | HyreADU calculation |
| Median declared valuation | $48,000 | $96,000 | 2.0× | HyreADU calculation |
| 25th to 75th percentile of declared valuation | $30,000 – $75,000 | $47,000 – $150,000 | — | HyreADU calculation |
| Median recorded floor area | 480 sq ft | 890 sq ft | 1.9× | HyreADU calculation |
| Share of permits completed | 67.8% | 59.5% | — | HyreADU calculation |
HyreADU calculation on LADBS resource pi9x-tg5x on data.lacity.org, 409,619 rows downloaded, refreshed 2026-08-30, retrieved 2026-09-05, using the department’s garage-conversion flag. The completion shares are the extract’s own status field and are a different measurement from the valuation columns.
Two independent signals point the same way. A conversion is declared at 0.5× the valuation of a non-garage unit on about 54% of the floor area, and the 2021 owner survey found garage work at a median construction cost of $90,000 against $180,000 for detached new construction — a ratio of two.
The instruments disagree wildly on level and agree closely on relative position, which is exactly what you would expect from a fee input that is biased but not random.
By planning area, inside one city
A single citywide figure hides a great deal even without leaving Los Angeles. Splitting new-construction permits on the city’s Area Planning Commission boundaries shows medians that barely move and tails that move enormously — which is itself informative about what the field is measuring.
| Area Planning Commission | n | p25 | Median | p75 | p90 | Class |
|---|---|---|---|---|---|---|
| Central | 503 | $86,750 | $148,000 | $313,117 | $500,000 | HyreADU calculation |
| East Los Angeles | 856 | $76,280 | $120,000 | $180,000 | $322,500 | HyreADU calculation |
| Harbor | 258 | $87,250 | $121,200 | $183,369 | $300,000 | HyreADU calculation |
| North Valley | 2,443 | $90,850 | $120,000 | $150,000 | $200,000 | HyreADU calculation |
| South Los Angeles | 1,501 | $80,000 | $120,000 | $184,000 | $382,000 | HyreADU calculation |
| South Valley | 2,696 | $85,000 | $120,000 | $160,000 | $320,000 | HyreADU calculation |
| West Los Angeles | 1,109 | $80,000 | $135,000 | $360,000 | $719,385 | HyreADU calculation |
HyreADU calculation on LADBS resource pi9x-tg5x on data.lacity.org, 409,619 rows downloaded, refreshed 2026-08-30, retrieved 2026-09-05, new-construction ADU permits only, split on the city’s Area Planning Commission geography.
Look at the medians, then look at the 90th percentiles. Five of the seven planning areas have a median within a few thousand dollars of $120,000, while the 90th percentile spans from $200,000 to $719,385 — a spread of about 3.6×.
A field that reflected construction cost would be expected to differ in the middle as well as the tail between, say, West Los Angeles and the Harbor.
A field whose center is anchored by convention and whose tail is free to reflect genuinely expensive projects would look exactly like this. We offer that as an observation about the instrument, not as a measurement of neighborhood construction costs.
Five jurisdictions, one statute, five practices
Levels, not rates — the extract windows differ and only Los Angeles supports the per-square-foot work. What the comparison shows is that the same statutory field, filled in under the same state law, produces medians that differ by a factor of 3.9×.
| Jurisdiction | Window (issued) | n (> $0) | Median | p90 | Maximum | Class | What shapes the number |
|---|---|---|---|---|---|---|---|
| City of Los Angeles | 2017-02-28 → 2023-05-19 | 3,809 | $40,000 | $125,000 | $17,500,000 | HyreADU calculation | Legacy contractor-bearing extract; contractor columns end 19 May 2023. |
| City and County of San Francisco | 2015-06-26 → 2026-08-28 | 1,314 | $150,000 | $403,500 | $3,500,000 | HyreADU calculation | Contractor license number on the permit; issued permits only. |
| City of Sacramento | 2018-10-29 → 2026-07-24 | 749 | $133,105 | $241,150 | $1,500,000 | HyreADU calculation | City publishes a $170.80/sf new-living-area valuation table (CDD-0245). |
| City of San José | 2008-02-11 → 2026-08-27 | 459 | $98,971 | $167,433 | $234,848 | HyreADU calculation | City points applicants at ICC construction-tax valuation rates. |
| Marin County (unincorporated) | 2014-04-10 → 2026-07-20 | 277 | $156,800 | $659,760 | $4,500,000 | HyreADU calculation | Unincorporated county land only. Small n, long right tail. |
HyreADU calculation from municipal permit harvests generated 29–30 August 2026, computed 2026-09-05. Owner-builder-named records excluded under Business and Professions Code § 7044; zero and missing valuations dropped. Declared permit valuation, not construction cost.
San José is the cleanest natural experiment on this page. Its declared valuations run from $25,091 to $234,848, with the maximum only 1.40 times the 90th percentile.
Compare unincorporated Marin, where the maximum is $4,500,000 against a 90th percentile of $659,760. A market of bids produces the second shape. A published valuation rate multiplied by floor area produces the first.
Some of the between-city spread is genuine — Marin does build larger and more expensively than Los Angeles — and much of it is which document the applicant was told to copy from.
Limits, stated as limits
- Nothing on this page accuses anybody of anything
Declared valuation runs low as a systematic property of how building-permit fees are assessed, in every jurisdiction that assesses them that way. Applicants frequently declare exactly what a city instruction or a published city valuation table tells them to.
No permit, applicant or contractor is named here in connection with a declared figure, and nothing on this page should be read as an allegation of under-declaration by anyone.
- The per-square-foot analysis is one city
The $120/sf headline is the City of Los Angeles, on new-construction permits adding exactly one ADU, because Los Angeles is the only one of the five jurisdictions publishing a departmental ADU flag and a floor-area field on the same complete extract. The five-city comparison is levels, not rates, and the extracts have different date windows.
- The cost anchor is somebody else’s survey, arithmetic-adjusted by us
The $461/sf figure is not a HyreADU survey and it is not a quote. It is the 2021 California ADU owner survey’s detached median carried forward on the DGS California Construction Cost Index from December 2019 to August 2026.
DGS itself cautions that the underlying index reports trends for specific trade labor and materials and “does not reflect current market bidding environment.” It is an anchor for a ratio, not a price for a project.
- Comparing a declared valuation to a full cost compares two scopes
Part of the four-to-one gap is under-declaration and part is that the two numbers were never measuring the same thing. We separate what we can and flag what we cannot. The ratio is a bound, not a decomposition.
- Recorded floor area is not interior livable space
The size distribution uses the department’s recorded floor-area field. The impact-fee statute measures interior livable space, defined at Government Code § 66313(e), which is a different measure and can differ on the same plan set.
The share “at or below 750 square feet” on this page is therefore not the share exempt from impact fees, and should not be quoted as one.
- Not financial advice, and not a budget
Nothing on this page is a cost estimate for any project. If you need a number for a specific lot, it comes from bids on a real scope, not from this page and not from a permit file. HyreADU does not design, permit or build accessory dwelling units.
Citing these figures
Link the permit-valuation study rather than this digest where you can: the frame construction, the exclusions and the reasons the two instruments were never measuring the same scope live there.
Every distribution on this page is a HyreADU calculation and should be attributed as one — “HyreADU analysis of City of Los Angeles building-permit valuations, LADBS resource pi9x-tg5x, retrieved 2026-09-05.” Carry the label with the number: it is declared permit valuation, not construction cost and not market value.
A figure from this page reprinted as “what ADUs cost in Los Angeles” would be reproducing the exact error the page was written to measure.
Where a figure is Agency published — Sacramento’s valuation rates, San José’s ICC basis, the index levels — cite the city form or the agency table. Where it is Trade / survey estimate, cite Chapple, Ganetsos and Lopez with the 2018–19 cohort attached.
Corrections are welcome and are published on the page with a dated note: hello@hyreadu.com. A jurisdiction publishing an ADU flag and a floor-area field on a complete extract is the single input that would most extend this work, because it would make the per-square-foot analysis available in a second city.
Questions
What is a declared permit valuation?
Is declared permit valuation the same as what an ADU costs?
What is the median ADU permit valuation in Los Angeles?
Has the declared valuation risen with construction inflation?
Why do declared valuations differ so much between California cities?
Are applicants under-declaring on purpose?
How big are Los Angeles ADUs, according to the permit file?
Which figures on this page are HyreADU’s own?
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 Socrata resource pi9x-tg5x (409,619 rows, refreshed 2026-08-30) downloaded and analyzed 2026-09-05; five-jurisdiction declared-valuation distributions computed 2026-09-05 from municipal harvests generated 29–30 August 2026; DGS California Construction Cost Index to August 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.
Sources & retrieval dates
- Los Angeles Department of Building and Safety — Building Permits Issued from 2020 to Present , Socrata resource pi9x-tg5x on data.lacity.org. 409,619 rows downloaded; refreshed 2026-08-30. Analysis frame: adu_changed > 0 OR junior_adu = 1; supplemental permits dropped by permit-number middle segment; issue year 2020 or later, giving 39,279 permits. Every distribution on this page — by year, by permit type, by garage flag, by recorded floor area, by Area Planning Commission, and per square foot — is a HyreADU calculation on this file. Retrieved 2026-09-05.
- HyreADU municipal permit harvests — Los Angeles, San Francisco, Sacramento, San José and unincorporated Marin , Generated 29–30 August 2026 from municipal open data; declared-valuation distributions computed 2026-09-05. Nested permit valuations; owner-builder-named contractor records excluded under Business and Professions Code § 7044; zero and missing valuations dropped; quartiles by linear interpolation on the sorted list. Helper file src/data/research/adu-cost-california-valuations.json. Declared permit valuation, not construction cost. Retrieved 2026-08-30.
- City of Sacramento — CDD-0245, Fees and Charges on Residential Building Permits, revised 12 July 2026 , The published residential valuation table: new living area $170.80 per square foot; garage conversion $101.16 per square foot. Where a city publishes the table it will use, declared valuation clusters on the table rather than on a market. Retrieved 2026-09-05.
- City of San José — Building and Structure Permits Fee Schedule, effective 10 August 2026 , ICC construction-tax valuation rates on page 25, effective 1 July 2026, are the basis the city points applicants at. The harvest for this jurisdiction runs from a minimum of $25,091 to a maximum of $234,848, a range too tidy for a market of bids. Retrieved 2026-09-05.
- San Francisco Department of Building Inspection — Table 1A-A, and City of Los Angeles LAMC Table 1-A , Both compute plan-check and permit fees from total declared valuation, which is the mechanism that gives the field its downward pull. San Francisco’s bands run on and after 12 July 2026; the published Los Angeles table structure is effective 16 July 2018, with plan check at 90 per cent of the building-permit fee under LAMC 91.107.3.1.1. Retrieved 2026-09-05.
- Karen Chapple, Dori Ganetsos and Emmanuel Lopez, Implementing the Backyard Revolution (UC Berkeley Center for Community Innovation, 22 April 2021) , The construction-cost anchor. Median construction cost $150,000 or $250 per square foot statewide, inclusive of design, labor, materials and permits; detached new construction $180,000 or $300 per square foot; garage work $90,000 or $189.19 per square foot. A survey of 2018–19 owners who finished, cited as CCI’s and never restated as ours. Retrieved 2026-09-05.
- California Department of General Services — California Construction Cost Index , ENR Building Cost Index averaged for San Francisco and Los Angeles only. December 2019 = 6,924; August 2026 = 10,633; factor 1.535673. DGS’s own qualifier travels with every anchor on this page: the index “does not reflect current market bidding environment.” Retrieved 2026-09-05.
- U.S. Census Bureau and HUD — Price Indexes of New Single-Family Houses Under Construction , Constant-quality Laspeyres index, 2005 = 100. Annual 2019 = 134.4; July 2026 preliminary = 199.8; factor 1.487. National, not Californian, and not ADU-specific. Published here only as a check that the choice of index is not driving the ratio. Retrieved 2026-09-05.
- California Business and Professions Code § 7044 and Government Code § 66313 , § 7044 is the owner-builder exemption under which permits naming OWNER-BUILDER are excluded from the contractor-named harvests. § 66313(e) defines livable space — the measure the impact-fee thresholds use, and not the same field as the recorded floor area in the permit extract. Retrieved 2026-09-05.
Never take a permit valuation as a construction budget
Declared permit valuation is the easiest ADU dollar figure in California to obtain and the easiest to misread. Median declared $120/sf against $461/sf indexed is not a small correction — it is a factor of about 3.8. If you need a number for a specific lot, it comes from bids on a real scope.
HyreADU does not design, permit or build accessory dwelling units. This page is informational and is not a cost estimate, a construction budget, or legal, tax or financial advice.
Every distribution on it is a HyreADU calculation on municipal open data, and every figure is a declared permit valuation — the amount an applicant entered on a building-permit application, used by the city to compute a fee.
It is not construction cost and it is not market value. Nothing on this page alleges under-declaration by any applicant, contractor or permit holder; declared valuation runs low as a systematic property of how building-permit fees are assessed, and in several of these jurisdictions the applicant is following a published city valuation table.
The construction-cost anchors are a 2018–19 owner survey indexed by the California Construction Cost Index, which the Department of General Services states does not reflect the current market bidding environment; they are anchors for a ratio, not prices for a project.
Per-square-foot analysis is confined to the City of Los Angeles because it is the only jurisdiction in this set publishing an ADU flag and a floor-area field on the same complete extract; recorded floor area is not interior livable space, the measure the impact-fee statute uses.
The five-jurisdiction comparison is of levels across different extract windows. If you need a number for a specific lot, it comes from written bids on a real scope.