ADU size and height limits in Los Angeles

By los-angeles.com EditorialEdited by Dolev NehoraiLast updated September 30, 2026State ADU statutes and LAMC 12.22 A.33, checked September 30, 2026Reviewed by Gregory G. Brown, Esq., Brown & Charbonneau, LLP

The Los Angeles ordinance allows an ADU of up to 1,200 square feet, attached or detached. That is the maximum on the City's own ordinance pathway rather than a cap on every ADU at the address: the state-law pathways, a conversion of existing space in particular, are governed by Government Code 66323 and follow their own size rules. Underneath it sit two separate state protections, and they answer different objections. The first is about development standards: a local development standard cannot preclude you building an ADU of at least 800 square feet with 4 foot side and rear setbacks. Reach for it when a setback, a lot coverage rule or a specific plan is being used to squeeze the unit. The second is about maximum sizes: a local agency cannot set a maximum ADU size below 850 square feet for a studio or one-bedroom unit, or below 1,000 square feet for a unit with more than one bedroom. Reach for it when the city's own cap is the problem. The 800 square feet does not answer that one, and treating it as though it did is the most common way this subject is got wrong.

A detached ADU gets at least 16 feet. Within 0.5 mile walking distance of a major transit stop or a high-quality transit corridor that becomes 18 feet. Another 2 feet is allowed where it is used to pitch the roof to match the primary dwelling, which is the allowance that lets an ADU look like the house rather than like a box behind it. An attached ADU may go to 25 feet or the height of the primary dwelling, whichever is lower.

Side and rear setbacks are four feet. A conversion of existing space adds none of its own, which is the sentence that makes a garage on a property line convertible at all. Run an address through the ADU feasibility checker and it prints the city figure and the state protections side by side.

On this page

Three numbers that answer three different questions
Height, and the two additions to it
Setbacks, and why a conversion is different
Common questions

Three numbers that answer three different questions

The 1,200 square feet is what the Los Angeles ordinance allows. It is the answer to "how big can I go on the city's own route", and it is more generous than state law requires. What it is not is a cap on every ADU at the address: the state-law pathways under Government Code 66323, a conversion of existing space above all, are governed by their own size rules rather than by this figure. Reading 1,200 as the ceiling on everything is how an owner talks themselves out of a conversion that is not bound by it.

The 800 square feet is a protection against a development standard. Government Code 66321(b)(3): a local development standard cannot preclude you building an ADU of at least 800 square feet with four foot side and rear setbacks. Reach for it when a setback, a lot coverage rule or a specific plan is being used to squeeze the unit. It is not a general minimum size for every ADU and it is not an answer to every refusal, which is the way it is most often misused.

The 850 and the 1,000 are a different protection again, and it is the one people need more often than they realize. A local agency cannot set a maximum ADU size below 850 square feet for a studio or a one-bedroom unit, or below 1,000 square feet for a unit with more than one bedroom. That is the number to reach for when the city's own cap is the problem. The 800 does not answer that, and treating one protection as though it were the other is the most common way this subject goes wrong. The full list is on the state ADU law floor page.

LA ADU Feasibility Checker

Check an address against the Los Angeles ADU ordinance and the California state floor: which types are allowed, how many, how big, and what the city cannot refuse.

Height, and the two additions to it

Sixteen feet is the base for a detached unit. Two things add to it and they add for different reasons.

Eighteen feet is the allowance in two circumstances rather than one, and the second gets forgotten. The first is proximity to transit: within half a mile walking distance of a major transit stop or a high-quality transit corridor. Walking distance rather than a straight line, which usually costs you rather than helps: the crow flies through a freeway and you do not. The second is a detached ADU on a lot with an existing or proposed multifamily building. Either one gets you to eighteen feet; they are not conditions to satisfy together.

Separately, and on top of whichever of those applies, two more feet are allowed where they are used to pitch the roof so it aligns with the primary dwelling. Sixteen plus two, or eighteen plus two. That is the allowance that lets an ADU read as part of the house rather than as a box behind it, and it is the one most often left on the table because nobody asked for it.

An attached ADU is capped differently: twenty-five feet or the height of the primary dwelling, whichever is lower. On a single-story house that second half is the binding one, and it is the reason an attached unit is sometimes the smaller option on a lot where the detached version would be taller.

Setbacks, and why a conversion is different

Four feet at the side and the rear. For anything newly built, that is the number.

For a conversion of existing space, no setback is added at all. The garage is where it is, and a city cannot require it to move as the price of converting it. Fire and life-safety requirements still apply to the structure, which is a different kind of requirement from a zoning setback and gets dealt with in the plans rather than by relocating the building. That is most of why a garage conversion is the cheapest route to an ADU on a narrow lot.

Size and height are also where a project stops being a legal question and becomes a drawing. Being allowed a given size and having room for it are separate findings, and how many ADUs the lot can take settles only the first.

Common questions

Can a local standard hold me to less than 800 square feet?

A local development standard cannot preclude you building an ADU of at least 800 square feet with four foot side and rear setbacks. That is Government Code 66321(b)(3), and it is the protection to reach for when a setback, a lot coverage rule or a specific plan is being applied in a way that would take you under it. It is a protection against a standard rather than a general minimum size for every ADU. If the problem is instead that the city's maximum is too small, that is a different protection: no local agency may cap an ADU below 850 square feet for a studio or one bedroom, or below 1,000 square feet above one bedroom. Los Angeles itself allows up to 1,200 on its ordinance route, so neither is usually the binding constraint here. This is general information rather than legal advice.

Does the two foot roof pitch bonus apply automatically?

It is available where the extra height is used to pitch the roof so it aligns with the primary dwelling, so it depends on the design rather than being granted by default. It sits on top of whichever base applies, so sixteen plus two, or eighteen plus two where the unit qualifies for the transit or multifamily allowance. It is worth raising with whoever is drawing the plans, because it is the difference between a flat-roofed box and a structure that matches the house, and it is frequently unused simply because nobody brought it up. This is general information rather than legal advice.

How is the half mile to transit measured?

As walking distance rather than as a straight line. That usually works against you: the direct line crosses a freeway, a rail corridor or a wall, and the walk goes around. If your lot is near the boundary, get the measurement rather than estimating it, because the same half mile decides both the eighteen foot height and whether any parking can be required at all. Two answers turn on one measurement. This is general information rather than legal advice.

Related guides

How many ADUs can I build?The counts differ for a single-family lot, a multifamily building and a condominium. What California guarantees, and which number we will not give you.
Converting a garage to an ADU in Los AngelesThe cheapest route to an ADU, and the rules that make it possible: no added setback, generally no replacement parking, and the demolition permit issued alongside.
What the city cannot deny you under state ADU lawCalifornia sets a floor under every ADU application. Los Angeles can be more generous and cannot go below it. The floor, line by line, with the statute.

The rules on this page are still being checked against the LA Housing Department and the municipal code. Nothing here quotes a figure that has not been confirmed.