The Complete Guide to Permitting an ADU or Tiny Home in Los Angeles (2026)

The Complete Guide to Permitting an ADU or Tiny Home in Los Angeles (2026)

Building an accessory dwelling unit (ADU) in Los Angeles is one of the smartest ways to add living space, rental income, or housing for family. But "Los Angeles" is not one permitting system — it's several, and the single most expensive mistake homeowners make is filing with the wrong department. This guide walks you through the entire 2026 process in plain English: the three legal paths, every form and permit you'll touch, who issues it, the order it happens in, and what it costs.

Use this as your map. Each named permit links to its own deep-dive post when you need the details.

First, the big picture: City vs. County vs. Tiny Home

There is no universal "LA ADU permit." Which forms you file depends entirely on which government controls your parcel and what kind of structure you're building.

The three jurisdictions

• City of Los Angeles — Permits run through the Los Angeles Department of Building and Safety (LADBS) and City Planning. This is the largest homeowner audience.
• Unincorporated LA County — Land outside the 88 incorporated cities. This is a two-department process: the Department of Regional Planning (DRP) handles land-use approval first, then Public Works Building & Safety (BSD) issues the building permit. Everything routes through the EPIC-LA online portal.
• Another incorporated city (Pasadena, Long Beach, Santa Monica, etc.) — Each has its own building department and its own rules. This guide covers the City of LA and unincorporated County; if you land in a different city, that city is your authority.

The three structure paths

1. A foundation-set ADU or JADU — Site-built or factory-built, on a permanent foundation. This is the standard, most common path and works in both City and County.
2. A Movable Tiny House (MTH) on wheels — Permittable as an ADU only inside the City of Los Angeles, under a special ordinance. The County has no movable-tiny-house path: the wheels and tongue must come off and the unit must sit on an approved foundation.
3. An uncertified RV or tiny-house-on-wheels (THOW) — Legally a vehicle, not a permittable dwelling anywhere in LA. If you want to live in it legally, it must either become a certified MTH (City only) or be set on a foundation.

Get this right before you spend a dollar on plans.

Step 1: Confirm your jurisdiction and eligibility

Every project starts the same way — look up your parcel. The Z-NET Jurisdiction & Zoning Lookup (a free LA County GIS tool) tells you whether you're in the City, unincorporated County, or another city, plus your zoning and overlays. If your parcel shows "masked out in white," it's inside a city — go to that city. Confirm a legal primary dwelling exists and that an ADU/JADU is allowed.

This single free step determines every department, portal, and form that follows.

Step 2: Choose your structure and legal path

Decide now whether you're building a foundation-set ADU, pursuing the City's Movable Tiny House path, or buying a factory-built unit. This choice drives the certifications you'll need later (covered below).

Step 3 (Recommended): Pre-consult and consider a pre-approved plan

Before hiring a designer, consider a pre-approved Standard Plan to skip structural plan check entirely:

• City: the LADBS ADU Standard Plan Program (including the free City-owned YOU-ADU design).
• County: the free County Pre-Approved ADU Standard Plans (Plan A / B / C).

These are separate, non-interchangeable catalogs — a County plan cannot permit a City project, and vice versa. DRP and LADBS both offer free planner consultations.

Step 4: Hire a designer and produce your plans

You'll need a full plan set: site/plot plan, floor plans, elevations, and foundation plans. Depending on your path:

• Factory-built unit → it must carry the HCD Factory-Built Housing (FBH) Insignia, the state's proof the structure already passed code review in the factory.
• Movable Tiny House (City) → secure ANSI A119.5 / NFPA 1192 third-party certification, DMV RV/Park Model registration, and meet the City's IB-P-ZC-2020-021 Movable Tiny House guidelines.

Step 5 (Unincorporated County only): Regional Planning approval

This is the County's distinct planning gate, and it comes before any building permit. File the Regional Planning Base Application in EPIC-LA, uploading your Land Use Application, the Site-Specific Plot Plan, architectural plans, and property photos. DRP runs a Ministerial Site Plan Review — a by-right zoning sign-off with a 60-day statutory clock and 2-year validity.

For a Junior ADU, you must record the JADU Owner-Occupancy Covenant before plans can be approved. City of LA homeowners skip this entire step — they go straight to LADBS.

Step 6: Submit your building permit application

• City → the LADBS ADU Building Permit via PermitLA / ePlanLA / LADBS Go.
• County → the Residential New Construction Building Permit (BSD) via EPIC-LA, filed after DRP approval.

Either way, your package includes structural plans and calcs (or the Garage-Conversion Standard Notes & Details for that common ADU type), Title 24 energy calcs and the mandatory solar PV package for new detached ADUs, and — in the County — your DRP-approved plans.

Step 7: Clear plan check

Reviewers return correction items. In the City, this is the ADU/JADU/MTH Plan Check Correction List (PC.STR.Corr.Lst.20A) — the official checklist your engineer should pre-clear before submitting. In the County, you're measured against the Minimum Plan Submittal Requirements for ADU/JADU. Incomplete submittals are the #1 cause of delay. Correct and resubmit until approved.

Step 8 (County): Clear every agency on your referral sheet

This is the County's hidden critical path. At intake, BSD issues an Agency Referral Sheet listing every outside agency you must clear before the permit issues:

• Fire / fire-flow via Form 195 – Fire Flow Availability
• A water-purveyor Will-Serve Letter
• Septic / Environmental Health, the Sanitation District, and school developer fees
• An optional ½-Fractional Address Request if the ADU needs its own street address

The permit will not issue until all marked clearances are complete.

Step 9: Pay fees and get your permit issued

Pay plan-check and permit fees. The County schedules a pre-construction meeting for Standard-Notes and garage-conversion projects.

Step 10: Build, inspect, and get your Certificate of Occupancy

Build, request inspections through the portal (City: LADBS; County: EPIC-LA), and pass final inspection.

Already have an unpermitted unit? There's a separate amnesty track. Under AB 2533 Unpermitted-ADU Legalization (County AM 80.12), ADUs/JADUs built before January 1, 2020 can be legalized using notarized checklists, applying only the minimum life-safety standards in effect at original construction — with penalties and most impact fees restricted.

A niche alternative: agricultural employee housing

On unincorporated agricultural parcels, certified tiny homes or RVs housing farm workers can be permitted as employee housing under a Permit to Operate – Employee Housing instead of as an ADU — often a cheaper, by-right path for rural and ag land.

Timeline at a glance

Fees at a glance

These are 2026 figures and third-party estimates where noted — always confirm with the official fee calculator for your parcel.

Key fee waivers to know: ADUs under 750 sq ft are exempt from development impact fees; ADUs of 500 sq ft or less are exempt from school fees under SB 543 (effective Jan 1, 2026); the pre-approved standard plans are free.

The bottom line

The LA ADU process is navigable once you know your jurisdiction. City of LA homeowners deal with one department (LADBS) and have the unique option of a Movable Tiny House. Unincorporated County homeowners run a two-department gauntlet — Regional Planning first, then Building & Safety — where the Agency Referral Sheet is the real critical path. Start with the free Z-NET lookup, consider a pre-approved plan to skip structural plan check, and build the slow items (covenants, agency clearances, certifications) into your timeline early. Each linked permit post above walks you through that single document in detail.

Individual permit posts in this cluster

• Z-NET Jurisdiction & Zoning Lookup (LA County) — free DRP GIS tool that confirms whether your parcel is City, unincorporated County, or another city before you spend a dollar; dedicated post.
• Regional Planning Base Application (with Land Use Application) — the County's umbrella planning case opened first in EPIC-LA; dedicated post.
• Site-Specific Plot Plan (LA County ADU) — scaled lot drawing on the County template tying your ADU to your parcel; dedicated post.
• Ministerial Site Plan Review (ADU) — the County's by-right zoning sign-off with a 60-day clock and 2-year validity; dedicated post.
• JADU Owner-Occupancy & No-Separate-Sale Covenant — recorded deed restriction required before JADU plans are approved; dedicated post.
• LADBS Accessory Dwelling Unit (ADU) Building Permit — the core City of LA building permit, required even with a pre-approved plan; dedicated post.
• Residential New Construction Building Permit – LA County (ADU/JADU) — the County BSD construction permit filed after DRP approval; dedicated post.
• ADU/JADU/Movable Tiny House Plan Check Correction List (PC.STR.Corr.Lst.20A) — the LADBS structural correction checklist to pre-clear; dedicated post.
• LADBS ADU Standard Plan Program — City pre-approved plans (incl. free YOU-ADU) that skip full plan check; dedicated post.
• LA County Pre-Approved ADU Standard Plans (Plan A/B/C) — free County-owned designs that skip structural plan check; dedicated post.
• Minimum Plan Submittal Requirements for ADU/JADU — BSD's content checklist for a complete County submittal; dedicated post.
• Garage-Conversion Standard Notes & Details (with Owner's Agreement) — pre-engineered sheet that replaces custom structural calcs for garage conversions; dedicated post.
• Title 24 Energy Compliance (CF1R) & Mandatory Solar PV — required energy docs plus the solar mandate for new detached ADUs; dedicated post.
• Agency Referral Sheet (LA County Building & Safety) — the master list of outside-agency clearances that gate County permit issuance; dedicated post.
• Form 195 – Fire Flow Availability — water-purveyor fire-flow certification that can avoid a full Fire review; dedicated post.
• Water Will-Serve Letter — purveyor letter confirming water service to the new ADU, a required County clearance; dedicated post.
• ½-Fractional Address Request — optional assignment of a separate ADU street address via LA County MPM; dedicated post.
• AB 2533 Unpermitted-ADU Legalization (AM 80.12, Attachments A & B) — amnesty path for pre-2020 unpermitted ADUs/JADUs; dedicated post.
• HCD Factory-Built Housing (FBH) Insignia — state certification on prefab/modular ADUs that skips field plan check; dedicated post.
• Movable Tiny House Certification (ANSI A119.5 / NFPA 1192) — third-party label separating a permittable City MTH from a plain RV; dedicated post.
• DMV Recreational Vehicle / Park Model Registration & Title (REG 343) — titles the MTH as a vehicle, the legal hook for the City MTH-as-ADU path; dedicated post.
• LADBS Information Bulletin P/ZC 2023-021 (formerly 2020-021) – Movable Tiny House Guidelines — the City's controlling how-to for the MTH path; dedicated post.
• Permit to Operate – Employee Housing (Agricultural Path) — by-right HCD operating license for certified worker housing on ag land; dedicated post.