A junior accessory dwelling unit (JADU) is a unit of no more than 500 square feet of interior livable space created entirely inside an existing or proposed single-family house, including an attached garage, with its own entrance and an efficiency kitchen; it may share a bathroom with the main house. Because a JADU reuses the roof, walls and floor you already have, it is usually the least expensive legal way to add a second unit, and it pays no development impact fees. Green Design and Build is a licensed, bonded and insured general contractor (CSLB #1110975) based in Van Nuys, building ADUs, JADUs and garage conversions for homeowners across Los Angeles County, Orange County, Ventura County, western Riverside County and western San Bernardino County (Ontario, Rancho Cucamonga and neighbouring cities).
We are led by Dekel Sofer; the company has completed hundreds of projects and holds a 4.7-star rating across 146 reviews on Yelp.
What a JADU is, in the words of the law
The rules for junior ADUs sit in California Government Code section 66333, and every city in our service area, including the City of Los Angeles, has to allow them. Verified against the Department of Housing and Community Development’s ADU Handbook (March 2026 edition), the definition has six parts:
- Size. No more than 500 square feet. Since January 1, 2026 the statute measures “interior livable space,” so wall thickness does not count against you.
- Location. Contained entirely within the single-family residence. An attached garage counts as part of the house, so converting an attached two-car garage into a JADU is the most common version we build. A detached garage cannot be a JADU; it becomes a garage conversion ADU instead.
- Kitchen. An efficiency kitchen, which the statute defines as “a cooking facility with appliances, a food preparation counter, and storage cabinets that are of reasonable size in relation to the size of the JADU.” A city cannot demand a specific counter length, a 240-volt range circuit or a full-size stove.
- Bathroom. A JADU “may include separate sanitation facilities or may share sanitation facilities with the existing structure.” If it shares, it must have its own exterior entrance and an interior door into the main living area.
- Owner occupancy. Since January 1, 2026 (AB 1154), the owner must live in either the house or the JADU only when the JADU shares a bathroom with the house. Give the JADU its own bathroom and no owner-occupancy requirement applies. The requirement never applies when the owner is a government agency, land trust or housing organization.
- Deed restriction. The city may require a recorded deed restriction that does two things and only two: prohibits selling the JADU separately from the house, and holds the unit to the size and attributes state law allows. The City of Los Angeles records it before the permit issues.
Two more rules matter. Only one JADU is allowed per lot. And no city may require parking for a JADU, even when it replaces an attached garage.
JADU plus ADU: the two-unit lot
The reason JADUs are worth knowing about is Government Code section 66323. On a single-family lot, a city must ministerially approve one JADU (or one ADU converted from existing space) together with one new detached ADU of up to 800 square feet with four-foot side and rear setbacks. That is how a standard 1950s Valley ranch house on a 6,000-square-foot lot ends up with three legal units: the house, a JADU in the attached garage, and a detached unit in the back yard. The detached unit is where most of the money and the rental value sit; the JADU is the inexpensive second one. Our ADU rules hub and the ADU rules calculator show the minimums your city has to allow for both.
How much does a JADU cost in Los Angeles?
A JADU in Los Angeles typically costs $60,000 to $150,000. That figure and every other on this page are typical Los Angeles budgeting estimates, not a price list or a quote. Your project can come in lower or higher depending on the house, the scope and the finishes; the only real number is a written proposal after a site visit.
The ceiling to compare against is the published range for a garage conversion ADU, $100,000 to $200,000, because a JADU built in an attached garage is the same shell with less plumbing: it can share the bathroom, and its kitchen is a cooking counter rather than a full kitchen with a range hood ducted through the roof. A JADU carved out of a bedroom wing with a new exterior door and no bathroom of its own sits at the low end; a garage JADU with its own bathroom, a new slab section for the drain, and a panel upgrade sits at the high end and overlaps the garage-conversion range.
| Item | What it involves | What moves it |
|---|---|---|
| Structure and envelope | Insulating and sheathing garage walls, replacing the garage door with a framed wall and entry, new windows for egress and light | A garage slab with no vapor barrier has to be sealed or overlaid; sloped garage slabs need leveling |
| Efficiency kitchen | Counter, cabinets, sink, plug-in or small built-in appliances; a 20-amp circuit or two | A full range with a hood ducted outside turns it into a full kitchen and adds gas or 240-volt work |
| Bathroom | Optional; sharing the house bathroom removes the largest plumbing cost | Cutting the slab for a new drain, and where the sewer lateral runs |
| Electrical | New circuits, lighting to Title 24, smoke and carbon monoxide alarms | Many 1950s to 1970s houses need a 200-amp panel first; the published range for that upgrade is $6,000 to $8,000 |
| Heating and cooling | A ductless mini-split heat pump is the usual answer | Panel capacity and the outdoor unit’s location |
| Fire separation | Rated drywall and a self-closing door between the JADU and the house where the code requires it | Garage-to-house walls usually already have the rated layer; ceilings often do not |
| Permits and deed restriction | LADBS or city plan check, the recorded covenant, inspections | No impact fees; connection fees are not charged for a unit inside existing space |
The published ranges for other ADU types are in our guide to how much it costs to build an ADU on your property, and the garage figures are broken down in our garage conversion cost guide.
JADU vs ADU vs garage conversion
| Junior ADU | Garage conversion ADU | Detached ADU | |
|---|---|---|---|
| Maximum size | 500 sq ft interior livable space | Existing garage footprint (plus up to 150 sq ft for entry and egress) | 800 sq ft guaranteed by state law; up to 1,200 sq ft in the City of Los Angeles and many other cities |
| Where | Inside the house or attached garage | Attached or detached garage | New building in the yard, 4 ft side and rear setbacks |
| Kitchen | Efficiency kitchen | Full kitchen | Full kitchen |
| Bathroom | Own or shared with the house | Own | Own |
| Owner must live on site | Only if the bathroom is shared | No | No |
| Deed restriction | Yes, in most cities | No | No |
| Impact fees | None | None (750 sq ft or less) | None at 750 sq ft or less; proportionate above |
| Replacement parking | None required | None required | None required |
| Fire sprinklers | Not required if the house has none | Not required if the house has none | Not required if the house has none |
| Solar | Not required | Not required | Required on new detached units in the City of Los Angeles |
| Can be combined with | One detached ADU up to 800 sq ft | One JADU | One JADU or one conversion ADU |
| Rental term | Longer than 30 days | Longer than 30 days | Longer than 30 days |
| Typical Los Angeles budgeting range | $60,000–$150,000 | $100,000–$200,000 | $180,000–$450,000+ by size |
When a JADU beats a full ADU
A JADU is the right unit when the budget is the constraint, when the yard is not there, or when the second unit is for family rather than rent. It makes sense for a parent or an adult child who will share the house’s bathroom without friction, for a lot where a detached unit would eat the only outdoor space, and for a homeowner who wants a second permitted unit in months rather than a year. It is also the right first step on a lot that will eventually get a detached ADU too, because the JADU approval does not use up the detached-unit entitlement.
A full ADU is the better answer when rental income is the goal, because a 500-square-foot unit that shares a bathroom and has a hot plate rents for far less than a self-contained unit with its own kitchen and bath; when the only convertible space is a detached garage, which can never be a JADU; and when you do not want a deed restriction or an owner-occupancy condition on title. Our guides to detached ADU vs garage conversion and ADU vs room addition cover the other two decisions on the same lot.
Permits and the 60-day clock
A JADU is a ministerial permit, the same as an ADU. In the City of Los Angeles, including Van Nuys, Sherman Oaks, Encino, Studio City, Woodland Hills, Northridge and North Hollywood, the plans go to LADBS; Burbank, Glendale, Pasadena, Santa Clarita, every Orange County city and the western Riverside and San Bernardino County cities each run their own building divisions under the same state law. The agency has 15 business days to tell you whether the application is complete and then 60 days to approve or deny it. The deed restriction is recorded with the county before the permit issues, and the inspections are the ordinary building, electrical, plumbing and mechanical inspections plus the final.
Inside the house the code issues are practical rather than legal: a bedroom used as a JADU still needs an egress window, the wall and ceiling between an attached garage JADU and the house need the rated drywall and the self-closing door the residential code requires for a garage, and every sleeping room gets interconnected smoke alarms. None of it is hard; all of it should be on the drawings before plan check rather than discovered by the inspector.
How long does a JADU take?
A JADU is the fastest legal second unit because there is no foundation, no roof and usually no utility trenching. Design and drawings take a few weeks, plan check runs inside the statutory 60 days when the submittal is complete, and construction on an attached-garage JADU is measured in weeks rather than months: framing the door opening, rough electrical and any plumbing, insulation, drywall, the kitchen counter, flooring and finish. Six months to a year is the published range for an ADU project overall; a JADU sits at the short end of it, and our how long does an ADU take guide breaks the phases down.
A real garage that became a unit
Our garage-to-ADU conversion in Los Angeles, finished in 2025, shows what the fuller version of this work looks like: a detached two-car garage of about 500 square feet by the pool, with the roof structure rebuilt, new framing and sheathing, new windows and French doors where the garage door had been, stucco to match the tile roof, a full kitchen with an island, a tiled bathroom with a glass shower and wood-look flooring throughout, now a long-term rental. Because the garage was detached it had to be a full ADU rather than a JADU, with its own bathroom and a complete kitchen. A JADU in an attached garage keeps most of that scope and drops the parts that cost the most: the second bathroom’s plumbing and the full kitchen.
The other lesson comes from why ADU quotes vary so much between contractors: a garage conversion estimated at $85,000 to $95,000 that finished near $130,000 after the slab turned out to have no moisture barrier, the 100-amp panel had to become 200 amps, and a camera found root damage in the sewer line. Every one of those applies to an attached-garage JADU too, which is why our site walk starts with the slab, the panel and the sewer.
Where we build JADUs
We build JADUs and ADUs from our Van Nuys office across the San Fernando Valley and the rest of Los Angeles County, where the attached-garage ranch house is the natural JADU candidate; in Orange County, where master-planned communities add HOA review that state law limits but does not remove; in Ventura County; and in western Riverside County and western San Bernardino County, where newer slab-on-grade houses with three-car garages leave room for both a JADU and parking. See every city we serve on our service areas page, and the full picture of what we build on our ADU page and garage conversion page.
Junior ADU FAQs
How much does a junior ADU cost in Los Angeles?
A junior ADU in Los Angeles typically costs $60,000 to $150,000, a typical Los Angeles budgeting range and not a quote; a garage conversion ADU, the closest comparison, runs $100,000 to $200,000 in our published ranges. A JADU that shares the house bathroom and uses a plug-in efficiency kitchen sits at the low end; one with its own bathroom, a slab cut for a new drain and a panel upgrade sits at the high end. These are estimates, not a price list, and the only real number is a written proposal after a site visit.
What is the difference between a JADU and an ADU?
A JADU is limited to 500 square feet of interior livable space, must be inside the existing house or attached garage, needs only an efficiency kitchen, may share a bathroom with the house, and carries a deed restriction and, if the bathroom is shared, an owner-occupancy requirement. An ADU is a fully independent unit with its own kitchen and bathroom, can be detached or converted from a detached garage, can be larger, and has no owner-occupancy condition.
Do I have to live on the property if I build a JADU?
Only if the JADU shares a bathroom with the main house. Since January 1, 2026, California Government Code section 66333 lets a city require owner occupancy of a junior ADU only when the unit shares sanitation facilities with the house; a JADU with its own bathroom carries no owner-occupancy requirement. Some cities still record a covenant on every JADU, so ask before you file.
Can I have a JADU and a detached ADU on the same lot?
Yes. Government Code section 66323 requires cities to approve, on a single-family lot, one junior ADU or one ADU converted from existing space together with one new detached ADU of up to 800 square feet with four-foot side and rear setbacks. A JADU in the attached garage and a detached unit in the back yard is the most common two-unit layout we build in the San Fernando Valley.
Does a JADU need its own kitchen and bathroom?
A JADU needs an efficiency kitchen, which state law defines as a cooking facility with appliances, a food preparation counter and storage cabinets of a reasonable size for the unit; it does not need a full range or hood. It does not need its own bathroom and may share the house’s, in which case it must have a separate exterior entrance and an interior door to the main living area.
Can I convert my detached garage into a JADU?
No. A junior ADU must be contained entirely within the single-family residence, and an attached garage counts as part of the house but a detached garage does not. A detached garage becomes a garage conversion ADU instead, with a full kitchen and its own bathroom, which is a larger scope with a published Los Angeles range of $100,000 to $200,000.
Find out whether your garage should be a JADU or an ADU
Send us your address and a photo of the garage or the room you have in mind. We will walk the lot, check the slab, the panel and the sewer, tell you which unit the law and the house allow, and give you a written, itemized estimate. The site visit and the estimate are free.