Title 24 Duct Leakage Testing Requirements in Los Angeles: 2026 Guide

Could a duct repair or replacement hold up permit sign-off, even when the HVAC equipment itself is working well? In Los Angeles, the Title 24 duct leakage testing requirements Los Angeles homeowners need to understand depend on the project scope, the applicable code cycle, and how compliance is documented.

It’s reasonable to feel uncertain when online guidance gives different thresholds or exemptions. California’s 2025 Building Energy Efficiency Standards took effect January 1, 2026, but the requirements that apply to your project depend on its permit date and the work being done. Duct leakage verification is performed by an independent rater, while any needed duct sealing or repairs are handled separately.

This guide explains which project details can trigger testing, what to expect during verification and documentation, and what to plan for when repairing, sealing, or replacing ducts. Around the Clock Heating and Air Conditioning provides residential duct repair, sealing, replacement, and insulation across Greater Los Angeles, including Los Angeles, Northridge, Woodland Hills, Canoga Park, Glendale, and Burbank. These services can address ductwork issues as part of a well-planned HVAC project.

When Title 24 Duct Leakage Tests Apply in Los Angeles

Duct leakage testing measures how much air escapes from a duct system under specified test conditions. In a permitted project, the result can help verify that the system meets the applicable California energy code. Testing is not automatically required for every HVAC repair or equipment change. The answer depends on the work performed, whether the system uses ducts, and the code edition governing the permit.

California’s Title 24, Part 6 sits within the broader California Building Standards Code. The 2025 energy standards apply to projects with permits submitted on or after January 1, 2026; earlier permit applications generally fall under the prior 2022 cycle. To understand the Title 24 duct leakage testing requirements for a Los Angeles project, confirm the permit date and applicable code provisions rather than relying on a general rule found online.

Which residential HVAC projects may trigger a duct test?

Project categories help frame the question, but they do not replace checking the code language for the specific job. New construction with a ducted forced-air system may require verification. Replacing ducts or making substantial changes to an existing duct system may also trigger testing, depending on the alteration and the applicable code pathway.

Equipment-only work is different. Replacing a furnace or air conditioner without changing ductwork does not, by itself, establish whether a duct test is required. The permit scope and current requirements still matter. Likewise, a frequently repeated duct-length threshold should not be treated as universal. Confirm the exact measurement, alteration definition, and any exception in the governing California Energy Code and local permit requirements before planning around it.

For a useful first review, note which equipment and duct sections are being installed, replaced, or modified. A ductless system has no duct network to test for leakage, though other energy-code provisions may still apply to the project.

How Los Angeles permit jurisdiction affects the answer

California sets the statewide energy standards, while the local authority having jurisdiction administers permits and inspections. The project address determines which building department handles the application. A home within the City of Los Angeles generally falls under the Los Angeles Department of Building and Safety. A nearby city or unincorporated area may have a different building authority and process.

Before work begins, match the property address to its building department and review that authority’s current residential permit guidance. Then confirm the permit date, described scope, and duct-test documentation requirements with the authority handling the project. This is especially useful when estimates describe work differently, such as “duct repair” versus “duct replacement.” Clear scope language helps prevent assumptions about whether testing is needed.

What Does California Title 24 Require for Duct Leakage Testing?

Title 24 does not set one leakage limit that can be applied to every residential project. The applicable requirement depends on the code edition, type of work, duct system, and permitted verification path. A percentage without those details can mislead because it may refer to a different project category or measurement method.

The California Energy Commission publishes the state’s Building Energy Efficiency Standards. Use the edition governing the permit and its relevant residential provisions to confirm the applicable limit, test method, exceptions, and documentation. The table below distinguishes common measurement concepts and project contexts. It is not a substitute for checking a code-specific threshold.

Term or project context	What it describes	What to confirm
Total duct leakage	Air escaping from the duct system under the specified test conditions.	The applicable code limit, measurement basis, and denominator for the project.
Duct leakage to outside	Air escaping from ducts to spaces outside the building’s conditioned area.	Whether this test path is permitted and what limit applies to it.
New construction or altered ducts	Different work categories that may follow different compliance provisions.	Permit code cycle, scope, system configuration, and required verification path.

How to read leakage limits and test pathways

A leakage percentage needs context. Its denominator may be the system’s nominal airflow or another basis specified for that test. Total leakage and leakage to outside are not interchangeable: they measure different boundaries, so a limit for one cannot be assumed to apply to the other. Before comparing a reported result with a threshold, match the test type and denominator to the code provision governing the project.

Scope matters, too. New construction, duct alterations, and replacement work may have different routes to compliance. Treat a duct-length trigger or percentage found online as applicable only when the current code edition and its specific provision support it. Do not rely on a figure without its edition, section, test type, and project scope.

What HERS verification and low-leakage options mean

HERS, or the Home Energy Rating System, is California’s framework for independent field verification of certain energy-code measures. A qualified verifier documents whether the specified measure meets the applicable requirements. Some code pathways may allow alternatives, including provisions for qualifying low-leakage systems, but eligibility and paperwork depend on the current standard. Confirm that an alternative meets its conditions before relying on it.

For homeowners, the practical step is to keep the permit scope, test method, applicable code edition, and verification documents aligned. That makes it easier to understand what a test result means and what correction, if any, is needed. If duct repairs are part of the project, reviewing current HVAC specials may help with planning that work, separate from official code verification.

How Is a Title 24 Duct Leakage Test Performed and Recorded?

A duct test is one part of a wider permit process. The work scope and applicable code pathway are established first. Then a qualified verifier measures leakage and records the result. If the system needs correction, duct repair or sealing is separate work. Passing a test, completing the paperwork, and receiving permit approval are related steps, but they are not the same thing.

What happens during duct pressurization testing?

For a typical fan-pressurization test, the verifier temporarily seals openings such as supply and return registers, then connects a calibrated fan to the duct system. The fan pressurizes the ducts to the test level specified by the applicable procedure. A measuring instrument records the airflow needed to maintain that pressure. The result is compared with the limit for the project’s code edition and test pathway.

The selected method defines what the measurement represents. A total leakage test measures leakage from the duct system as a whole. A leakage-to-outside test focuses on air escaping beyond the building’s conditioned area. These results use different boundaries and should not be treated as interchangeable. The test report should make clear which method was used and which applicable limit was evaluated.

Who verifies results and what gets documented?

Under the 2025 code framework, the qualified third-party verifier is referred to as an Energy Code Compliance (ECC) Rater. Older projects and guidance may use the term HERS Rater. HERS verification applies where the specific compliance pathway calls for it. The verifier’s role is distinct from the installing HVAC contractor’s work. Around the Clock provides residential duct repair, sealing, replacement, and insulation, while independent verification documents code compliance where required.

1. Scope is established. The project team identifies the duct work, applicable code cycle, required test method, and verification steps.
2. The system is tested. The verifier conducts the applicable measurement and compares the result with the standard for that project.
3. Results are recorded. For applicable verification pathways, the rater completes the required compliance documentation, such as a CF3R form, and submits the record through the state registry, as required.
4. Permit review follows. The local building department reviews required records as part of its permit and inspection process. Documentation supports review, but it does not guarantee approval.

The contractor coordinates installation or corrective work and provides project details needed for verification. The homeowner can help by arranging access to the HVAC equipment and ductwork, keeping copies of permit and test documents, and tracking any correction or retest. The local authority administers the permit and determines what it needs for review.

For the Title 24 duct leakage testing requirements Los Angeles homeowners are working through, keep the test result, verification record, and permit scope together. If the result identifies leakage, use the documented findings to guide duct repairs or sealing, then follow the applicable process for any retest.

How Can Los Angeles Homeowners Prepare for Testing or Address a Failed Result?

A little preparation can make the test visit more straightforward and help keep permit records organized. Focus on three things: the paperwork describing the work, access to the relevant equipment and ducts, and a shared understanding of what the test covers. The Title 24 duct leakage testing requirements Los Angeles projects must meet depend on the permitted scope, so clear records matter before and after testing.

What should homeowners have ready before the test?

Gather the permit information and project documents you already have. Include the work description, equipment or duct replacement details, and any previous test or inspection records. These help the project team and verifier work from the same description of the system and the changes made.

• Keep the scope clear. Note which duct sections were repaired, replaced, or modified, and whether the equipment was changed too.
• Prepare access. Clear a path to the air handler, accessible duct runs, and other areas included in the test. Secure pets and move stored items that could obstruct access.
• Align expectations. Before the scheduled test, clarify with the project team which test method applies and what documentation is expected. Keep copies of the test record and any permit-related correspondence.

Do not prepare the system by sealing registers or changing duct connections yourself. The verifier needs to conduct the test under the conditions required for the applicable procedure. If the project includes equipment replacement, precise notes about whether ductwork was also altered can help distinguish the work scope.

What should happen after a failed test?

A failed result is a finding to investigate, not a reason to guess at a fix. Review the test record with the project team to understand what was measured, which limit applied, and whether the report identifies leakage areas. Depending on the test method and findings, leakage may involve duct runs, connections, boots, or other parts of the tested system.

Use those findings to guide corrective work. Professional duct repair or sealing can address identified leakage, but no single material or repair guarantees that a system will pass. After corrections, the required verification process determines the result. Follow the applicable code and permit instructions for any retest and updated documentation.

For systems without ducts, such as ductless mini-splits, a duct leakage test does not apply to a nonexistent duct network. Other project requirements may still apply, so keep the system type and permit scope clear. Duct condition can also affect overall home efficiency. Homeowners comparing whole-home cooling options may find it useful to consider how ducted systems perform alongside an energy-efficient air conditioning approach.

Once the test record identifies work to address, Around the Clock’s residential duct repair and sealing services can help with the ductwork itself. The required independent verification remains a separate step.

How Around the Clock Supports Los Angeles Homeowners With Ductwork

Code requirements define when verification is needed. The condition of the ductwork is a separate, practical concern. Around the Clock Heating and Air Conditioning helps residential homeowners in Greater Los Angeles and the San Fernando Valley with duct repair, sealing, replacement, and insulation. We serve homeowners in Los Angeles, Northridge, Woodland Hills, Canoga Park, Glendale, and Burbank, addressing ductwork needs whether you are responding to a documented test finding or looking into comfort concerns such as uneven airflow.

Our factory-trained, NATE- and EPA-certified technicians service all makes and models. Around the Clock is family-owned and has operated since 1967. Ductwork services can address identified leakage or damaged sections, while required testing and official documentation remain part of the applicable independent verification process.

When residential duct repair or sealing may be relevant

A test report can point to leakage that needs attention. A homeowner may also notice rooms that feel less comfortable than others or ductwork that appears damaged. Those observations are useful context, but they do not replace testing or establish the cause. We tailor duct repair, sealing, replacement, or insulation to the home and the work involved, with the aim of addressing the ductwork concern without promising a particular test result.

Not every issue calls for the same solution. A localized connection problem may call for focused repair or sealing, while worn or unsuitable sections may need a different approach. An inspection can help clarify the condition of accessible ductwork and inform a practical scope. For broader HVAC care, we also provide routine yearly maintenance and tune-ups. These support general system upkeep, but are not a substitute for code-required testing or verification.

If you are planning ductwork alongside other HVAC changes, clear project details help keep the work organized. Our team provides a free-of-charge consultation, quote, inspection, and estimate. A rapid response repair team is on call for repair needs, and our residential HVAC support is tailored to the system and home.

Plan a practical next step in Los Angeles

Start with the details you have: the test report, permit scope, prior inspection notes, or a description of the airflow concern. We can help you understand the ductwork condition and outline repair, sealing, replacement, or insulation options. Keep any required independent verification separate from repair work, so each part of the project has a clear role.

For support with residential ductwork, our team brings focused experience and attentive service to each project. Review current offers as you plan the work.

Turn Your Ductwork Plan Into a Clear Next Step

Before scheduling work, put the project details in one place: the permit scope, the ducts being changed, any test findings, and the documentation the authority requires. This gives everyone involved a shared reference and helps you distinguish corrective ductwork from the independent verification process. For the Title 24 duct leakage testing requirements Los Angeles projects must follow, clarity on scope is a practical place to start.

If a test has identified leakage, use its findings to shape the repair plan. Duct sealing or replacement can address documented issues, but the verifier’s results determine whether the system meets the applicable standard. Keep that distinction clear as you plan, and retain the records for permit review.

For help understanding your home’s ductwork needs, Around the Clock Heating and Air Conditioning can provide a free-of-charge consultation, quote, inspection, and estimate for residential ductwork services. Explore current HVAC specials as you plan your next step.

A well-defined plan makes the path ahead easier to manage. Call Around the Clock Heating and Air Conditioning at (818) 765-8183 to discuss residential ductwork service.

Frequently Asked Questions

Does replacing an HVAC unit trigger duct leakage testing under Title 24?

Replacing an HVAC unit alone does not automatically mean a duct leakage test is required. The answer depends on whether the project also changes ductwork, the system configuration, the permit scope, and the code edition that applies. For example, replacing a furnace while leaving existing ducts untouched differs from replacing the furnace and substantial duct sections. In Los Angeles, use the permitted work description and the local building department’s requirements to determine the applicable pathway.

Are ducts located entirely inside conditioned space exempt from Title 24 testing?

Not necessarily. Ducts inside conditioned space may affect which compliance provisions or test options apply, but their location alone should not be treated as a universal exemption. The applicable code edition, system design, project scope, and verification pathway all matter. Review the relevant code language and permit instructions for the home. If the ducts are within a conditioned area, include that detail in the project description so it can be evaluated against the correct requirements.

Does a ductless mini-split system require duct leakage testing?

A ductless mini-split has no duct network to test for duct leakage. That does not mean the entire installation is exempt from energy-code or permit requirements. The project may still need to meet other provisions based on its scope and jurisdiction. For a home in Los Angeles or a nearby city, identify the system as ductless in the permit documents and follow the local authority’s review process for the work being performed.

Can duct sealing alone satisfy Title 24 duct leakage requirements?

No. Sealing may reduce leakage, but the repair itself does not demonstrate code compliance where verification is required. The applicable test must measure the system using the method and limit for that project. If a report identifies leakage, use its findings to guide sealing or other repairs, then complete any required verification or retest. A repair should address the diagnosed issue, not be treated as a substitute for the documented result.

Does a routine AC tune-up include a Title 24 duct leakage test?

No. A routine AC tune-up is general HVAC maintenance, not automatically a code-compliance test. A tune-up may review system operation, but permit-related duct verification follows its own scope and documentation requirements. If your Los Angeles project requires testing, keep it separate from routine maintenance when planning the work. This distinction helps prevent confusion between ongoing system care and formal verification connected to a permitted alteration or installation.

Can a homeowner perform a duct leakage test for permit compliance?

A homeowner can review project records and prepare access, but should not assume a self-performed test will count as official compliance verification. Where the applicable pathway requires independent verification, a qualified rater must perform and document the test. A homeowner’s informal check may help identify a concern, but it does not replace the required method or record. Follow the permit instructions for the property’s jurisdiction and applicable code cycle.

What documentation should I keep after a Title 24 duct test?

Keep the test result and any required compliance certificate or registry record, along with the permit, work description, and related inspection documents. If the system needed corrections, retain the repair details and subsequent test records too. These records help connect the measured result to the work completed and support questions during permit review. Keep copies together with the project address and permit information, especially if you later alter or replace the HVAC system.