Research study
Garage conversions: the most common ADU permit in Los Angeles
Half the ADU permits the city issues are not new buildings. They are an existing structure being reclassified as somewhere a person may sleep — which is a fire, egress and electrical problem before it is a design one.
Written by HyreADU Research Desk Primary-source research and data analysis
Audited by HyreADU Research Desk Classifier audit and scope-of-claim review
The finding
In the City of Los Angeles, 19,294 of 39,279 ADU-adding building permits issued between 1 January 2020 and 2026-08-30 — 49.1% — carry a work description that describes converting a garage. That share has been between 38% and 61% in every year of the window, so the conversion is not a phase the city is passing through.
The conversion is the cheap lane on paper and the small lane in fact. Median declared permit valuation is $48,000 against $96,000 on every other ADU permit — but a declared valuation is a fee input, not a construction cost, and we treat it that way on its own page.
Median permitted floor area is 480 square feet against 890. It is also the lane that finishes. 67.8% of conversion permits in the frame have reached a certificate of occupancy or a permit final, against 59.5% of the rest.
This is a Los Angeles number and nothing else. Los Angeles is the only jurisdiction this desk has found that publishes a departmental ADU flag on a complete permit extract.
We do not have a California garage-conversion share, and we will not manufacture one from a one-city file.
And a garage that is legal to park in is not a garage that is legal to sleep in. The work that closes that gap — fire separation from the remaining garage or the house, an egress opening, a compliant ceiling height, foundation and slab work, a service upgrade, gas and smoke and carbon-monoxide alarms — is exactly the work a plan checker exists to look at. Nothing on this page is a construction instruction.
Read this first
- One city. Not California, not the country.
Every share, median and count on this page is the City of Los Angeles.
Los Angeles publishes
adu_changedandjunior_aduon a complete, refreshed permit extract; San Francisco, Sacramento, San José and unincorporated Marin do not publish an equivalent flag on a comparable file, and the state Annual Progress Report has no unit-type breakdown that separates a conversion from a new build.So we can say what Los Angeles permits look like and we cannot say what California permits look like. We are not going to blur that.
- The garage classifier is ours, not the department’s
LADBS flags an ADU. It does not flag a garage conversion. We read the department’s own free-text
work_descand count a permit as a conversion where it contains both a form of “garage” and a form of “conver”.That deliberately misses conversions described only as “existing accessory structure”, and it catches a small number of permits where a garage is mentioned for another reason.
The sensitivity table below shows both directions, and the true share is very likely a little higher than the one we publish.
- A declared valuation is not a construction cost and not a price
The valuation figures here are what the applicant declared to the city on the permit application.
In most California fee schedules that number drives the plan-check and permit fee, which gives it a systematic downward pull, and it routinely excludes design, engineering, impact fees, utility connection and the contractor’s margin.
We quantify that pull separately in what builders tell the city an ADU is worth. Do not read the medians here as budgets.
- A permit is not a completion
Two-thirds of conversion permits in this frame have a completion event on the record. The rest are open: still building, abandoned, expired, or finished without the certificate being recorded against this permit number. The completion shares here are observed matches in one municipal file, not a construction census.
- This page contains no construction guidance
Fire separation, egress, ceiling height, structural work at the old garage door opening, the electrical service and any gas line are life-safety items governed by the California Residential Code, the California Fire Code and the local amendments.
HyreADU does not design, permit or build. The useful next step is the plan check counter and a licensed professional.
Why the conversion dominates the permit file
A detached ADU is a new building. It needs a foundation, a structure, a roof, a separate utility path and a piece of the yard the household is currently using for something else.
A garage conversion needs none of those things in the same quantity, because the foundation, the walls, the roof and — usually — the setback nonconformity already exist and are already there lawfully.
State law leans hard in the same direction. Government Code section 66314 requires a permitting agency to allow the conversion of existing accessory structure space to an ADU, and to do it without imposing the setbacks it would impose on a new structure, provided the exterior dimensions are not expanded.
That is a very large advantage for an existing garage, and it is the reason a converted garage frequently sits four feet from a property line where a new detached unit could not.
HyreADU analysis. The share of Los Angeles ADU permits describing a conversion has not drifted meaningfully in seven years of issuance.
It was 60.6% in 2020 and 44.6% in 2025, with a trough of 37.6% in between.
Where a share is this stable across a period in which the statute changed four times, the driver is more plausibly the housing stock than the policy: the city has a very large number of detached and attached garages built when a car was the only thing anyone expected to keep in them.
The other half of the frame is not one thing. It is new detached construction, attached additions, junior ADUs carved out of the house, and conversions of accessory structures that nobody wrote the word "garage" next to. We keep those separate below rather than treating "not a garage" as a category.
A conversion permit against every other ADU permit
The same frame, split on our garage classifier. Read the valuation rows as declared valuations, which is what they are.
| Measure | Garage conversion | Every other ADU permit | What the difference is not |
|---|---|---|---|
| Permits in the frame | 19,294 | 19,985 | Not a unit count — one ADU can draw more than one permit, though supplementals are already removed. |
| Median declared valuation | $48,000 | $96,000 | Not a cost, not a bid, not a price. It is the number the applicant put on the application, and in most fee schedules it drives the fee. |
| Declared valuation, 25th–75th percentile | $30,000 – $75,000 | $47,000 – $150,000 | Not a range of quotes. Half of each group sits inside its band; the tails are wide in both. |
| Median permitted floor area | 480 sq ft | 890 sq ft | Not necessarily the ADU alone. On an alteration permit the square-footage field can describe the scope of work rather than the finished unit. |
| Share with a completion event on the permit | 67.8% | 59.5% | Not a completion rate for ADUs. It is the share of permits carrying a certificate of occupancy or a permit final in this file on this date. |
| Dominant permit type | Alteration/repair (11,491) and addition (7,793) | New construction and addition | Not a proxy for attached versus detached. A detached garage converted in place is still an alteration. |
All figures: HYRE calculation on LADBS resource pi9x-tg5x, 39,279 non-supplemental ADU-flagged permits issued 2020 to 2026-08-30, retrieved 2026-09-05.
The money gap, and what it is not
The median declared valuation on a conversion permit is $48,000. On every other ADU permit in the frame it is $96,000 — very close to double. The interquartile ranges barely overlap: three-quarters of conversion permits declare under $75,000, while a quarter of the rest declare over $150,000.
What that gap is evidence of: that applicants and their contractors consistently tell the city a conversion is a smaller job than a new build. Given that a conversion reuses a foundation, a slab, walls and a roof, that is the expected direction and the magnitude is not surprising.
What that gap is not evidence of: what either job costs. Declared valuation is systematically low, because in most California fee schedules it is the input to the permit fee.
The nearest defensible cost anchor we hold is the Terner Center’s 2021 owner survey, indexed forward on published construction-cost indices — a median of $138,211 for a garage conversion and $276,421 for a detached unit in August 2026 money.
Those are HYRE arithmetic on someone else’s survey, they are not a quote, and we set them out with their whole chain in the California ADU cost study.
The honest way to read both numbers together is as a ratio rather than a level. The declared-valuation ratio between a conversion and the rest of the frame is about 0.50 to 1.
The indexed-cost ratio between a garage conversion and a detached unit is about 0.50 to 1. Two entirely different instruments, pointing the same way, at about the same size. That is the sort of agreement worth reporting; it is not a cost figure.
The four rules that actually govern a garage conversion
The four rules below are descriptions of published state law as retrieved on 5 September 2026, with the section numbers as they stand after the 1 January 2026 renumbering. They are not legal advice and they are not a design specification.
The conversion right itself
Government Code section 66314 requires a permitting agency’s ADU ordinance to allow an accessory dwelling unit created by converting existing space in an accessory structure, and section 66323 sets out the ministerial approval path in which a qualifying unit is approved without discretionary review or a hearing.
The practical consequence at the counter is that the question stops being “will the city allow this” and becomes “does the drawing meet the objective standard”. That is a plan-check question, and it is why so much of the difficulty in a conversion is code rather than politics.
Replacement parking
The provision homeowners most often get wrong. Where a garage, carport or covered parking structure is demolished or converted to make an accessory dwelling unit, state law does not require the displaced off-street parking to be replaced. That has been the rule since the 2019 package and it survived both recodifications.
It does not mean the street will accommodate the car, and it does not override a recorded covenant, a homeowners association rule that is itself lawful, or a permit parking district. It means the city cannot make replacement parking a condition of the ADU.
Setbacks on the existing footprint
A conversion of existing accessory-structure space within the existing exterior dimensions does not have to meet the setback a new structure would. This is the reason a converted garage can sit on a rear lot line where a new detached unit could not.
Push the walls out, raise the roof, or add floor area, and the exemption stops covering the new part. That boundary — existing dimensions versus expansion — is the single most consequential drafting decision in a conversion project.
The building code, which is where the money goes
None of the zoning relief above touches the California Residential Code. A converted garage becomes habitable space, and habitable space carries requirements a garage never had: minimum ceiling height, an emergency escape and rescue opening in a sleeping room, fire separation from any remaining garage and from the dwelling, insulation and energy compliance, a compliant electrical service, smoke and carbon-monoxide alarms, and — where the slab was sloped to a garage door — a floor that is now the floor of a room.
We are not going to tell you how to do any of that. It is life-safety work, it is jurisdiction-specific, and it belongs to a licensed designer, a licensed contractor and the plan checker.
What we will say is that this list, not the zoning, is where the difference between a cheap conversion and an expensive one lives.
Sensitivity: how much does the classifier move the headline?
The headline share depends on a keyword rule we wrote. So here is the rule loosened and tightened, on the same frame, so a reader can see how much of the finding is ours and how much is the data’s.
| Specification | Permits matched | Share of frame | What it does |
|---|---|---|---|
| Published headline — work description contains a form of “garage” and a form of “conver” | 19,294 | 49.1% | Conservative. Requires the applicant to have written both ideas into the description. |
| Loosened — work description mentions a garage at all | 22,983 | 58.5% | Upper bound. Includes permits where a garage is mentioned because the ADU is above it, beside it, or because the garage is being kept. |
| Restricted to alteration/repair permits only | 11,491 | 29.3% | Lower bound on “conversion of an existing structure”, and it drops the 7,793 conversion permits filed as additions. |
| All alteration/repair ADU permits, garage or not | 16,439 | 41.9% | The department’s own “existing structure” lane, which is the widest defensible reading of “conversion”. |
All four specifications run on the same 39,279 non-supplemental ADU-flagged permits. HYRE calculation on LADBS resource pi9x-tg5x, retrieved 2026-09-05. The headline is the most conservative of the four that still means what the words say.
The spread between the conservative headline and the loosened upper bound is real and we are not going to average it away.
What the four specifications agree on is the finding that matters: on any reasonable reading, converting an existing structure is either the largest single category of Los Angeles ADU permitting or is tied with it.
Method
Reproducible from a named public resource. Anyone who wants to check this can.
- 1 Download the whole resource, not a query
LADBS publishes Building Permits Issued from 2020 to Present as Socrata resource
pi9x-tg5xon data.lacity.org. We downloaded all 409,619 rows on 2026-09-05; the department’s ownrefresh_timefield runs to 2026-08-30. Filtering server-side would have hidden how many rows we discarded, so we did not. - 2 Take the department’s ADU flag, not our own keyword
A row is in the frame if
adu_changedis greater than zero orjunior_aduis 1. These are LADBS fields, not ours. This is the same classifier as our construction-duration study, deliberately, so the two pages describe the same population. - 3 Drop supplemental permits
LADBS permit numbers take the form
21010-10000-05893, where the middle segment increments for each supplemental to an already-issued file. Supplementals are revisions and are excluded. That leaves 39,279 flagged non-supplemental permits across all issue years, and 39,279 issued from 2020. - 4 Classify the garage conversion from the department’s free text
The published headline requires
work_descto contain both a form of “garage” and a form of “conver”, case-insensitively. This is our rule and it is imperfect in both directions; the sensitivity table above shows the alternatives rather than burying them. - 5 Report valuation as declared, and floor area as permitted
The
valuationandsquare_footagefields are what the applicant put on the application and what the department recorded. Neither is a measurement HyreADU made. Percentiles are reported rather than means wherever a distribution is skewed, which here is everywhere. - 6 Treat a completion event as an observed match, never as a census
A permit is counted complete if it carries a
cofo_dateor a status of “Permit Finaled”. Everything else is open, and “open” includes finished-but-not-recorded. We publish shares of permits, not completion rates for buildings.
Where this page stops and HyreGarage starts
Ours, because it is a dwelling
The ADU ordinance and the state standards that override it. The parking-replacement rule. The setback treatment of existing accessory-structure space. Fire separation, egress and habitability, because those attach to the unit being habitable.
The permit record: how many, where, declared at what, finished how often. The contractor of record and what the license register says about them.
Not ours
The garage as a garage: the door, the opener, the slab as a parking slab, the structure as storage. That is a different question with a different buyer and it is not answered by ADU law.
And a boundary we hold in the other direction too: this page will not tell you how to build the conversion. Fire separation and electrical work in a converted garage are life-safety items. That belongs to a licensed professional and the plan check, not to a research page.
A frequency is not a recommendation
A 49.1% share of Los Angeles ADU permits describing a garage conversion tells you what the city’s housing stock and the state’s conversion rules made easy. It tells you nothing about whether converting your garage is the right decision on your lot.
A conversion gives up a parking structure and a large piece of storage permanently, it is usually constrained to the existing footprint and therefore to the existing shape, and it inherits whatever the old structure’s foundation, slab and framing actually are — which is not knowable from a permit file.
A new detached unit costs more and takes longer, and buys a plan that was drawn for a dwelling.
The comparison that matters is the one on your lot, with a surveyed footprint and a real scope. Our conversion versus new build tool lays out the questions; it will never tell you that you can build.
Terms, used precisely
- ADU-flagged permit
- A building permit on which LADBS recorded
adu_changedgreater than zero orjunior_aduequal to 1. The department’s classification, not ours. - Garage conversion (as used here)
- A permit in that frame whose departmental work description contains both a form of “garage” and a form of “conver”. Our classification, and an imperfect one.
- Declared valuation
- The construction value the applicant declared on the permit application. In most California fee schedules it is the input to the plan-check and permit fee. It is not a cost, a bid or a price.
- Permitted floor area
- The LADBS
square_footagefield on the permit. On a new-construction permit it is a good proxy for the unit; on an alteration permit it can describe the scope of work rather than the finished dwelling. - Completion event
- A certificate of occupancy date, or a status of “Permit Finaled”, on that permit number in this file on this date. Not a physical completion census.
- Junior ADU
- A unit of no more than 500 square feet of interior livable space contained entirely within a single-family residence. Statutorily a different animal from an ADU, with its own owner-occupancy rule — see the owner-occupancy study.
Questions
Is a garage conversion really the most common kind of ADU?
Do I have to replace the parking spaces I lose?
Does the converted garage have to meet the normal setbacks?
Why is the declared valuation so much lower than every cost guide I read?
Are garage conversions faster to build?
How big is a converted garage, typically?
Can I convert a garage that was built without a permit?
Is this a California figure?
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) downloaded and analyzed 2026-09-05; the department’s own refresh_time field runs to 2026-08-30. 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
- City of Los Angeles Department of Building and Safety — Building Permits Issued from 2020 to Present (Socrata resource pi9x-tg5x) , Full resource download, 409,619 rows, retrieved 2026-09-05. Fields used: permit_nbr, permit_type, issue_date, cofo_date, status_desc, valuation, square_footage, work_desc, apc, adu_changed, junior_adu, refresh_time. The department’s refresh_time field runs to 2026-08-30. The ADU frame is the department’s own adu_changed and junior_adu flags; the garage classifier is HyreADU’s keyword read of the department’s work_desc. Retrieved 2026-09-05.
- City of Los Angeles open data portal — dataset landing page for pi9x-tg5x , The publisher’s own description of the resource, its update cadence and its column definitions. Used to confirm that adu_changed and junior_adu are departmental fields rather than derived ones. Retrieved 2026-09-05.
- California Government Code § 66314 — the standards a local ADU ordinance may impose , The source of the conversion right, the treatment of existing accessory-structure space and the parking provisions. Part of Chapter 13, created by SB 477 (Stats. 2024, Ch. 7) and amended by the four bills chaptered 10 October 2025. Retrieved 2026-09-05.
- California Government Code § 66323 — ministerial approval of a qualifying ADU , The provision that makes a conforming application a plan-check question rather than a discretionary one. Retrieved 2026-09-05.
- California Government Code § 66313 — definitions, including the junior ADU , The 500-square-foot junior ADU definition used on this page. Amended by SB 543 (Stats. 2025, Ch. 520), operative 1 January 2026. Retrieved 2026-09-05.
- SB 543 (McNerney, 2025) — Accessory dwelling units. Stats. 2025, Ch. 520 , The second recodification of the ADU chapter in under two years. Renumbers § 66324 to § 66311.5, § 66327 to § 66313.5 and § 66332 to § 66311.7, operative 1 January 2026. Cited here because guidance about unpermitted garage conversions almost universally still cites § 66332. Retrieved 2026-09-05.
- HyreADU — declared-valuation extracts across five California jurisdictions , The per-jurisdiction valuation distributions and the indexation chain applied to the Terner Center’s 2021 medians, used here only for the ratio comparison. Computed 5 September 2026 from municipal harvests of LADBS, DataSF i98e-djp9, Sacramento BldgPermitIssued, San José CKAN and Marin mkbn-caye. Retrieved 2026-09-05.
Compare the two on your lot, not on a median
A conversion is cheaper on the permit and smaller in the finished unit, and it permanently gives up a structure you currently own. The comparison worth making is the one with your footprint and your scope in it.
HyreADU does not design, permit or build accessory dwelling units, and takes no payment for placement or a favorable mention. This page is informational: it is not legal advice, not tax or financial advice, and not construction guidance.
Fire separation, egress, structural, electrical and gas work in a garage conversion are life-safety items governed by the California Residential Code, the California Fire Code and local amendments, and belong to a licensed professional and the plan check.
Every count, share and percentile on this page is the City of Los Angeles only, computed from a named public permit extract retrieved on 5 September 2026; it is not a California or national statistic.
Declared permit valuation is a fee input, not a construction cost or a price. A permit is not a completion. Statutory descriptions are of published text as retrieved on 5 September 2026 and the chapter has been renumbered twice since March 2024.