½-Fractional Address Request (ADU Address Assignment), LA County

How to Get Your LA County ADU Its Own Address the ½ "Fractional" Address Request You built an ADU in the backyard, you're ready to rent it out, and you hit...

Written by 1-800-ADU-Pros

Last updated: July 16, 2026•7 min read

½-Fractional Address Request (ADU Address Assignment), LA County

How to Get Your LA County ADU Its Own Address (the ½ "Fractional" Address Request)

You built an ADU in the backyard, you're ready to rent it out, and you hit a surprisingly basic question: what's the address? Can your tenant get their own mail, their own utility account, their own spot on a delivery app? In unincorporated Los Angeles County, the answer often comes down to a small but specific request — the ½ fractional address.

Here's how it works, when you need it, and when you can skip it.

What a ½ fractional address actually is

A "fractional" address adds a ½ to your existing house number. If your home is 1234 Main Street, your ADU becomes 1234½ Main Street. It's a real, legal address — recognized by the post office, utilities, and 911 — but it's tied to your existing street number rather than a brand-new one.

These addresses are assigned by LA County Public Works' Survey/Mapping and Property Management Division (SMPM), often just called Mapping & Property Management (MPM). This is the office that assigns and maintains legal addresses across unincorporated LA County and notifies the utilities, USPS, and emergency responders once a new address exists.

Do you even need one?

This is the part most homeowners get wrong. An ADU is not required to have its own address. There are three scenarios:

You can skip it

If your ADU will share the main house's utility meter and receive mail at the existing address, you don't need a separate address at all. The ADU is simply permitted under your current house number.

It's optional (this is where the ½ comes in)

If you want the ADU separately addressed — for a cleaner rental, separate mail, or a separate utility account — but it sits on the same street frontage as your house, MPM assigns a ½ fractional number. That's the 1234½ scenario.

It's required

If your ADU has its own separate driveway or street access from the main house, a separate address is mandatory, not optional. The county will assign one as part of your permit.

It's not allowed

If you built a Junior ADU (JADU) rather than a full ADU, stop here. Under state law (SB 897, Government Code §65852.22(f)) and LA County's Building Official directive, a JADU is considered part of the primary dwelling. It cannot get a separate address or separate utilities under any circumstance.

How to request it

The good news: this isn't a separate trip to a counter. The address request rides along with your ADU building permit inside the county's EPIC-LA portal.

Confirm your ADU permit is in EPIC-LA. For residential projects in unincorporated areas, you'll need an approved Regional Planning Site Plan Review (a plan number starting with RPPL) to start the address request.
Start the Address Request and upload your documents: architectural plans, structural plans/calculations, and Title 24 energy sheets.
Pay the fee when EPIC-LA prompts you, once your application is deemed complete.
MPM assigns the ½ number. The new address is reserved for the ADU only and isn't released until every reviewing agency has cleared the project.
The address is finalized before your building permit is issued, and MPM notifies the utilities, post office, and emergency services.

If anything stalls, email the addressing team directly at Addressing@dpw.lacounty.gov.

Fees and timing

The cost is a modest house-number assignment fee from the county's Building Code fee schedule, collected through EPIC-LA. There's no single advertised "fractional address" price, and the schedule updates periodically (usually each July 1), so confirm the current amount at submittal or by emailing the addressing team. Expect it to be a rounding error next to your overall ADU permit cost.

On timing, there's no separate turnaround clock — the address is handled within plan check and must be locked in before your building permit issues. Submit complete plans up front and it resolves inside your normal permitting window.

The bottom line

If you want your ADU to stand on its own as a rental, the ½ fractional address is the clean way to do it — provided it's a full ADU and not a JADU. Decide early whether you need it, request it inside EPIC-LA alongside your permit, and don't let it become the thing that holds up your final sign-off.

This is general guidance for unincorporated LA County; rules differ inside incorporated cities. Confirm specifics with LA County Public Works before you file.

Reference card

Official number: No standalone form number — submitted as an "Address Request" in EPIC-LA; SMPM/MPM assigns it as a ½ fractional house number
Issuing body: LA County Public Works — Survey/Mapping and Property Management Division (SMPM), commonly referred to as Mapping & Property Management (MPM)
What it is: A request to give your accessory dwelling unit (ADU) its own legal address by adding a ½ ("fractional") number to your existing house number — turning 1234 Main Street into 1234½ Main Street for the ADU. SMPM/MPM is the LA County division that assigns and maintains legal addresses in unincorporated areas (and some contract cities) and notifies utility companies, mail services, and emergency responders when a new address is created. An ADU does not have to have its own address — it can be permitted under the existing address and share the primary home's meter and mail. The ½ fractional address is the mechanism used when a homeowner wants the ADU separately addressed but it shares the same street frontage as the main house.
Who needs it: Applies when you want your ADU to have its own address — for a separate rental, separate mail, or separate utility metering — and the ADU shares the same street frontage as the main house (a ½ fractional number is the typical assignment). It is REQUIRED, not optional, when the ADU has its own separate driveway or street access from the main house; in that case a separate address must be assigned. You can SKIP it when the ADU shares the primary residence's utility meter and receives mail at the main address. It is NOT allowed for a Junior ADU (JADU): per SB 897 (Gov. Code §65852.22(f)) and the LA County Building Official's directive, a JADU is part of the primary dwelling and cannot receive a separate address or separate utilities under any circumstance.
Fees: A house-number/address-assignment fee set in the LA County Building Code fee schedule and collected through EPIC-LA when your application is deemed complete. It is a modest administrative fee (a base house-number assignment charge plus a smaller charge per additional number) — far below the cost of the ADU permit itself. The county does not publish a single flat "fractional address" price; confirm the current amount in EPIC-LA at submittal or by emailing Addressing@dpw.lacounty.gov, since the schedule is updated periodically (typically each July 1).
Timeline: There is no published standalone turnaround for the address request — it is handled inside your ADU plan-check process rather than as a separate queue. Practically, the address is assigned during plan check and must be finalized before the building permit is issued, and the new number is not released until all reviewing agencies have cleared the project. Plan to have it resolved within your overall ADU permitting window (commonly several weeks to a few months). Submitting complete plans up front and emailing Addressing@dpw.lacounty.gov if it stalls are the fastest paths.

Requirements

An ADU building permit application already in progress in EPIC-LA (the address is assigned during plan check and must be issued before the building permit is finalized)
For residential addresses in unincorporated LA County: an approved Department of Regional Planning (DRP) Site Plan Review (a plan number beginning with RPPL), used to start the address request
Architectural plans uploaded to the EPIC-LA application
Structural plans and/or structural calculations
Title 24 energy sheets/calculations
Property/parcel identification (APN, existing site address)
Confirmation of how the ADU will be served — separate vs. shared utility meter and mail, and whether it has separate street access (this determines whether a separate address is required vs. optional)
Payment of the applicable house-number/address-assignment fee in EPIC-LA

How to file

Decide whether you actually need it: if the ADU shares the meter and gets mail at the main address, no separate address is needed. If it has its own driveway/street access, a separate address is required. Otherwise, a ½ fractional address is optional but available.
Confirm your ADU building permit is being processed through EPIC-LA (epicla.lacounty.gov) and, for residential projects in unincorporated areas, that you have the Regional Planning Site Plan Review (RPPL) needed to start an address request.
In EPIC-LA, start the Address Request and upload the required documents: architectural plans, structural plans/calculations, and Title 24 sheets.
Pay the application/house-number assignment fee when EPIC-LA prompts you after the application is deemed complete.
SMPM/MPM reviews the request and assigns the ½ fractional number (e.g., 1234½ Main Street). The new address is reserved for the ADU only and is not released until all reviewing agencies have cleared.
Once cleared, SMPM/MPM finalizes the address and notifies utilities, USPS, and emergency responders. The assigned address must be in place before your building permit is issued.
Questions or a stuck request: email the addressing team directly at Addressing@dpw.lacounty.gov.

Common pitfalls

Assuming every ADU needs its own address — it does not. Sharing the main home's meter and mail means no separate address is required at all.
Trying to get a separate address for a JADU — it is categorically not allowed under SB 897 / Gov. Code §65852.22(f); a JADU is part of the primary dwelling.
Not realizing a separate driveway/street access makes a separate address mandatory, not optional — this can surprise homeowners who wanted to keep one address.
Expecting a whole new street number — the standard assignment for an ADU on the same frontage is a ½ fractional number (1234½), not 1236 or a new number.
Treating it as a post-build add-on — the address must be assigned before the building permit is issued, so requesting it late can hold up permit issuance.
Skipping the Regional Planning Site Plan Review (RPPL) — residential address requests in unincorporated areas key off that approval; without it the EPIC-LA address request can't proceed.
Forgetting the new address is reserved/held until all agencies clear — you can't use or publish it (for leases, utilities, mail) until it's officially released.

Sources

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