Duct replacement permits in Palo Alto, CA

General California guidance last updated September 23, 2026 · Palo Alto data fully re-verified

What HVAC contractors need to know about pulling a duct replacement permit in Palo Alto (Santa Clara 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.

Palo Alto accepts submittal through the Accela Citizen Access (ACA) and has adopted the 2025 California Building Code (Title 24, Part 2) with Palo Alto amendments. Fee details and sources are below.

Palo Alto permit data

Sourced from public City of Palo Alto documents — every field carries the source URL and verification date.

Permit portal
Accela Citizen Access (ACA)

verified Aug 10, 2026 · source · The city's online permitting portal — all permit submittals go through ACA. Inspection scheduling, permit-history search, and fee payment are available on the portal without logging in

Adopted code edition

2025 California Building Code (Title 24, Part 2) with Palo Alto amendments

verified Aug 10, 2026 · source · Ordinance No. 5674 (passed October 20, 2025) adopts the 2025 California Building Code, Title 24 Part 2, Volumes 1 & 2, by reference with local omissions, amendments, exceptions, and additions

Fee schedule
Building Fees — FY 2027 Adopted Municipal Fee Schedule (Planning and Development Services)

verified Sep 13, 2026 · source · Linked as "Building Fees (PDF)" on the Building Permit Forms page; the FY 2027 schedule replaced the FY 2026 building-fee schedule

City of Palo Alto Planning & Development Services →All verified Palo Alto data →

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 Palo Alto-specific, see the statewide duct replacement guide.

Typically needs a permit

Duct replacement itself triggers a permit in nearly every California jurisdiction, Palo Alto included. Palo Alto-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 Palo Alto-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 Palo Alto 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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