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LADBS Accessory Dwelling Unit (ADU) Building Permit

The LADBS ADU Building Permit: A Plain-English Guide for LA Homeowners If you want to add a backyard cottage, convert your garage, or build a detached renta...

Written by 1-800-ADU-Pros

•7 min read

LADBS Accessory Dwelling Unit (ADU) Building Permit

The LADBS ADU Building Permit: A Plain-English Guide for LA Homeowners

If you want to add a backyard cottage, convert your garage, or build a detached rental unit in the City of Los Angeles, there is one document you cannot skip: the LADBS ADU building permit. It is the central approval that makes your Accessory Dwelling Unit legal. Here is exactly what it is, what you need, and how to get it without losing your mind.

What the ADU Building Permit Actually Is

An Accessory Dwelling Unit (ADU) is a small, separate living space on the same lot as a home — attached to the house, or a standalone structure like a converted garage or a backyard cottage. The Los Angeles Department of Building and Safety (LADBS) is the City agency that reviews your project and issues the permit that authorizes you to build.

During review (called a "Building Plan Check"), LADBS confirms your plans meet zoning, building, residential, energy (Title 24), and green (CalGreen) codes. Once it passes and fees are paid, the permit is issued and you can start construction — followed by required inspections.

"But I'm using a pre-approved plan — do I still need this?"

Yes. The City runs a Standard Plan Program, including the free, City-owned YOU-ADU plan, that lets you skip much of the design review. But the standard plan only speeds up plan check. You still must file for and pull a building permit, and LADBS still has to approve the plan for your specific lot.

Who Needs It (and Who Doesn't)

You need this permit for nearly any ADU project inside City of LA limits — a new detached ADU, an ADU attached to your house, or a garage/basement conversion (which still counts because it's a change of occupancy plus electrical and plumbing work). Junior ADUs and Movable Tiny Houses are covered too.

You do not file with LADBS if your property is in unincorporated LA County or another city like Long Beach or Pasadena. Those have their own building departments. When in doubt, check your parcel in the City's ZIMAS lookup first.

What You'll Need to File

  • A completed permit application (filed online)
  • A site/plot plan showing the lot, all existing and proposed structures, setbacks, dimensions, and total lot coverage
  • Architectural plans, plus structural plans and calculations sealed by a licensed CA architect or engineer where structural work is involved
  • Title 24 energy forms (CF-1R) for the new space
  • A CalGreen checklist with the responsible-party columns filled in by the licensed professional
  • Solar/PV plans for newly built detached ADUs (required by code)
  • Possible clearances from other departments (sewer, drainage, grading, fire) depending on your lot

How to File, Step by Step

  1. Confirm your property is inside the City of Los Angeles.
  2. Choose your design path: custom, or a pre-approved Standard Plan (start with the free YOU-ADU plan).
  3. Start your application online — ePlanLA (eplanla.lacity.org) for regular electronic plan check, or PermitLA for express/standard-plan online permits.
  4. Upload your full plan set (site plan, architectural/structural, Title 24, CalGreen, solar).
  5. Pay intake fees and submit for review.
  6. Resolve correction notices — revise and resubmit, comment by comment, until plan check is approved.
  7. Clear any other-department requirements (sewer, drainage, grading).
  8. Pay remaining fees and pull the permit.
  9. Build, then schedule inspections (foundation, framing, rough MEP, insulation, drywall, final).

Fees and Timeline

There is no flat fee. Cost depends on your project valuation plus plan-check, permit, and per-trade fees. Third-party estimates for 2026 commonly land around $3,000-$6,000 in City fees for a typical ADU. Good news: state law waives impact fees for ADUs under 750 sq ft and waives school fees for ADUs. Use the LADBS online Fee Estimator for your exact numbers.

For timing, plan check often runs about 15-25 business days for standard review (5-10 for express on smaller projects), with corrections adding more. State law requires the City to act on a complete ADU application within 60 days. Realistically, budget a few weeks to a few months from submittal to issued permit.

Common Pitfalls to Avoid

  • Missing or wrong Title 24 (CF-1R) forms — the #1 first-round correction.
  • A generic CalGreen checklist with blank responsible-party columns — returned every time.
  • A site plan where setbacks, dimensions, or lot coverage don't match the actual lot.
  • Forgetting solar plans on a new detached ADU.
  • Not anticipating sewer, drainage, or fire clearances on sloped or easement-adjacent lots.
  • Treating correction notices as rejection — they're a normal part of the process. Respond to each comment and resubmit.

The Bottom Line

The LADBS ADU building permit is the anchor of any City of LA ADU project. Get your plan set complete the first time — especially Title 24, CalGreen, and an accurate site plan — and the path from application to a backyard unit gets dramatically shorter.

Reference card

  • Official number: No single form number; filed as a Building Plan Check / Building Permit. ADU plan-check correction reference: PC/STR Correction List (e.g., PC-STR-CORR-LST-020A). City ADU authority: Ordinance 186,481, LAMC 12.22 A.33.
  • Issuing body: Los Angeles Department of Building and Safety (LADBS), City of Los Angeles
  • What it is: The core City of Los Angeles building permit required to legally construct an Accessory Dwelling Unit (ADU), Junior ADU (JADU), or Movable Tiny House on a residential lot inside City of LA limits. LADBS reviews the project as a "Building Plan Check" to confirm it meets zoning (LAMC), building, residential, energy (Title 24), and green (CalGreen) codes, then issues the permit that authorizes construction and the required inspections. It is required even when you use a pre-approved Standard Plan — the standard plan only speeds the design review; the building permit and a site-specific approval are still mandatory.
  • Who needs it: Anyone building a new detached ADU, attaching an ADU to an existing house, or converting existing space (garage, basement) into an ADU within the City of Los Angeles. It also covers JADUs and Movable Tiny Houses. You need it for essentially any ADU involving construction, electrical, plumbing, or mechanical work. You can skip it only if your property is in an unincorporated area or another city (e.g., Long Beach, Pasadena, county areas) — those are permitted by LA County or that city's building department, not LADBS. Note: even a converted-garage ADU with no new footprint still requires this permit because it is a change of occupancy plus MEP work.
  • Fees: No flat fee — cost is driven by project valuation plus plan-check, permit, and per-trade (electrical/plumbing/mechanical) fees. Industry estimates for 2026 commonly run roughly $3,000-$6,000 in City fees for a typical ADU (some larger/custom projects cited at $5,000-$15,000); an ADU around $150,000 valuation is often cited near $3,700. By state law, development impact fees are waived for ADUs under 750 sq ft, and school fees are waived for ADUs. The City-owned YOU-ADU standard plan is free. Use the LADBS online Fee Estimator for your specific valuation; figures here are third-party estimates, not an official LADBS schedule.
  • Timeline: Plan check is commonly cited at about 15-25 business days for a standard/regular review, or roughly 5-10 business days for express review (smaller, lower-valuation projects) — these are typical third-party estimates, not a guaranteed LADBS turnaround. Using an approved Standard Plan shortens the design portion of plan check. Corrections add time (each resubmittal round adds days to weeks). State ADU law requires the local agency to act on a complete ADU application within 60 days. Overall, from first submittal to issued permit, most City-of-LA ADUs take a few weeks to a few months depending on completeness, corrections, and required clearances.

Requirements

  • Completed building permit application (filed online via ePlanLA for plan check, or PermitLA for express/standard-plan online permits)
  • Site/plot plan showing the lot, all existing and proposed structures, setbacks, dimensions, and total lot coverage (must be internally consistent with lot dimensions)
  • Architectural plans (floor plans, elevations, sections); structural plans and calculations sealed by a CA-licensed architect or engineer where structural work is involved
  • Title 24 energy compliance forms (CF-1R) for the new conditioned space
  • CalGreen checklist for new construction, with the responsible-party columns completed by the appropriate licensed professional
  • Solar/photovoltaic plans for newly constructed detached ADUs (required by code)
  • Possible department clearances depending on the lot: Bureau of Engineering (sewer, drainage, grading, street/easement), LA Fire Department (access/fire), Planning, and Public Works/Sanitation
  • If using the Standard Plan Program: the selected approved standard plan (the City-owned YOU-ADU plan is free; privately owned approved plans are sold by their design firms)

How to file

  1. Confirm your property is inside the City of Los Angeles (use the LADBS/ZIMAS parcel lookup) — if it is in the County or another city, you file there instead.
  2. Decide your design path: a custom design, or a pre-approved Standard Plan (start with the free City-owned YOU-ADU plan at dbs.lacity.gov/adu/approved-standard-plans) to shorten plan check.
  3. Create an account and start your application online: ePlanLA (eplanla.lacity.org) for regular electronic plan check, or PermitLA (permitla.lacitydbs.org) for express/standard-plan online permits.
  4. Upload your plan set: site plan, architectural/structural plans, Title 24 (CF-1R), CalGreen checklist, and solar plans for detached new builds.
  5. Pay plan-check intake fees and submit for review. LADBS plan checkers (and any referred departments — Engineering, Fire, Planning) review and issue correction notices.
  6. Resolve corrections: revise the plans, respond to each comment, and resubmit through ePlanLA until the plan check is approved (back-and-forth is normal, often 1-3 rounds).
  7. Obtain any required department clearances (sewer, drainage, grading) before issuance.
  8. Pay the remaining permit fees and pull (issue) the building permit through the portal.
  9. Build and schedule inspections (foundation, framing, rough MEP, insulation, drywall, final) via the LADBS inspection request system; pass the final inspection for sign-off.

Common pitfalls

  • Assuming a pre-approved Standard Plan means no permit — you still must file and pull a building permit and get site-specific approval.
  • Missing or incorrect Title 24 (CF-1R) energy forms — the single most common first-round correction.
  • Submitting a generic CalGreen checklist without the responsible-party columns filled in by the licensed professional — returned every time.
  • Inaccurate site plan: setbacks, dimensions, or lot coverage that don't reconcile with the actual lot dimensions; exceeding the zone's lot coverage limit.
  • Forgetting solar/PV plans on a newly constructed detached ADU.
  • Not anticipating other-department clearances (Bureau of Engineering sewer/drainage/grading, Fire access) when the lot is near a slope, easement, or storm drain — these can stall issuance.
  • Filing with LADBS when the property is actually in LA County or another city's jurisdiction.
  • Treating LADBS correction notices as rejection — they are a normal, expected part of plan check; respond comment-by-comment and resubmit.

Sources

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