Duct replacement permits in Unincorporated Los Angeles County, CA

General California guidance last updated September 23, 2026 · Unincorporated Los Angeles County data fully re-verified

What HVAC contractors need to know about pulling a duct replacement permit in Unincorporated Los Angeles County.

Short answer

In California, replacing or extending ductwork requires a mechanical permit, and the Energy Code (Title 24, Part 6) treats it as an alteration: replacing a duct system entirely — or adding/replacing more than about 40 linear feet in unconditioned space — generally triggers duct sealing with third-party HERS leakage testing. Ducts must meet the insulation R-value for the climate zone. A C-20 (HVAC) licensed contractor generally pulls it.

Unincorporated Los Angeles County accepts submittal through the EPIC-LA (Electronic Permitting and Inspections for the County of Los Angeles) and has adopted the 2026 County of Los Angeles Building Code (Title 26), adopting the 2025 California Building Code with County amendments. Fee details and sources are below.

Unincorporated Los Angeles County permit data

Sourced from public Los Angeles County documents — every field carries the source URL and verification date.

Permit portal
EPIC-LA (Electronic Permitting and Inspections for the County of Los Angeles)

verified Sep 13, 2026 · source · Building and Safety's online portal for the unincorporated areas: submit plans, specifications, and supporting documents for review and approval, pay permit fees, and apply for a permit. Contract cities use the separate Building and Safety Online Plan Check System (BSOP)

Adopted code edition

2026 County of Los Angeles Building Code (Title 26), adopting the 2025 California Building Code with County amendments

verified Sep 13, 2026 · source · Title 26 Sec. 100 adopts the 2025 California Building Code by reference, except as changed or modified in Title 26 (Ord. 2025-0047). Per Public Works' codes page, the 2026 County codes took effect January 1, 2026 for projects with an application date on or after that date — https://pw.lacounty.gov/building-and-safety/general

Fee schedule
Building and Safety fee schedules (County section, 2026-27) — building permit fees effective July 1, 2026 in unincorporated Los Angeles County

verified Sep 13, 2026 · source · The County's Building Code Fee Schedule (Title 26) PDF sets building permit fees in the unincorporated territory effective July 1, 2026; the 2026-2027 County public notice announces a 3.4% increase effective July 1, 2026 — https://pw.lacounty.gov/bsd/lib/fp/fees/County/2026-2027%20County%20Public%20Notice.pdf. Electrical, mechanical, plumbing, grading, and valuation tables are listed on the same index page

The general picture in California

Ductwork replacement is permitted mechanical work across California, and the review is mostly an Energy Code review. Title 24, Part 6 treats duct work as an alteration: replace the system, or add or replace more than about 40 linear feet in unconditioned space, and duct sealing with third-party HERS leakage verification generally follows — documented on a CF1R-ALT and registered before final. The materials layer is simple but strictly checked: insulation at the climate zone's required R-value (R-6 or R-8 in most cases), joints sealed with mastic or listed UL 181 tape — never cloth-backed duct tape — and flex duct supported so it isn't kinked or compressed. Because the HERS rater is independent, the schedule needs their test and registration between substantial completion and final inspection. Fees, forms, and inspection scheduling are set per city — confirm with the local building department.

For deeper background that isn't Unincorporated Los Angeles County-specific, see the statewide duct replacement guide.

Typically needs a permit

Duct replacement itself triggers a permit in nearly every California jurisdiction, Unincorporated Los Angeles County included. Unincorporated Los Angeles County-specific variations are confirmed with the issuing department above.

Usually doesn't (general norm)

  • Maintenance sealing of accessible duct joints (verify locally)
  • Replacing registers and grilles
  • Repairing insulation on existing ducts

Documents & plans generally required

Common reasons duct replacement applications get bounced

Code-rooted patterns across California — not a Unincorporated Los Angeles County-specific rejection rate.

The inspection sequence

A typical order — the number of stops and exact sequence vary by jurisdiction and scope.

  1. 1Rough inspection where ducts are concealed in framing before cover
  2. 2Final inspection with the system complete and the HERS duct-leakage results registered where required

Licensing — who can pull it

Duct replacement in California is generally C-20 (HVAC) licensed work; a B (General Building) contractor may pull within a larger remodel under CSLB rules. The HERS duct test is performed by an independent third-party rater, not the installing contractor.

Other verified Unincorporated Los Angeles County notes

Frequently asked questions

Does a duct repair need a permit?

Small like-for-like repairs are often treated as maintenance, but replacement and extension are permitted mechanical work — and once the altered footage in unconditioned space passes roughly 40 linear feet, the Energy Code's sealing-and-testing requirements generally come with it. Describe the real scope; cities notice 'repairs' that replace half a system.

What leakage does the HERS test allow?

The allowed leakage is a percentage of system airflow set by the Energy Code, and it differs for new, entirely replaced, and altered duct systems. The practical version: mastic at every joint, tested by an independent HERS rater, results registered — an unregistered test doesn't close the permit.

What R-value do ducts need?

Title 24 sets duct insulation by climate zone — commonly R-6 or R-8 for ducts in unconditioned space, with R-8 required in many zones. The CF1R-ALT documents the value for the project's zone, and both the inspector and the HERS rater look at the duct label.

Do I need a separate permit if I'm also replacing the furnace or AC?

Usually one mechanical permit covers both scopes, but the energy paperwork compounds — the equipment changeout triggers its own measures and the duct replacement its own. The trap is pulling an equipment-only permit and 'discovering' the duct replacement at final.

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