Duct leakage records before balancing starts

Direct answer

A duct leakage record before balancing should prove which system or duct section was tested, what standard or project requirement controlled the test, who selected the test scope, what surface area and test pressure were used, what allowable leakage was calculated, what equipment and calibration were used, what openings were sealed, what leakage was measured, what repairs were made, what retest passed or failed, and whether the system was released, conditionally released, or held before TAB work starts.

This packet belongs before balancing because TAB work assumes the air distribution system is ready to measure and adjust. If leakage testing is missing, scoped differently from the specification, or still failing, a balance report can become a record of a moving target instead of a final system condition.

Use this as documentation guidance only. The adopted code, project specification, SMACNA or other referenced procedure, TAB standard, commissioning plan, engineer, owner representative, authority having jurisdiction, and qualified test agency control the actual test and acceptance decision.

Why leakage records belong before balancing

Balancing is not the same task as leak hunting. The balancing crew measures airflow, pressure, and related conditions, then adjusts dampers, valves, fans, and controls toward the specified distribution. If the duct system is still leaking beyond the allowed limit, the crew may spend time compensating for a construction defect that should have been repaired first.

NEBB sample specification language puts duct leakage testing under necessary mechanical work that should be complete before TAB work. That is the practical field rule: finish the leakage test chain before final damper settings are marked and reported.

The leakage packet also protects the sheet metal crew. If a section passes, the packet shows the test scope, allowable limit, measured result, and witness. If it fails, the packet shows the leak locations and repair/retest sequence instead of letting the issue surface during final balancing.

Define the test scope before the number

A leakage number without scope is not a useful record. The packet should say whether the test is residential total duct leakage, leakage to outdoors, rough-in, final, or commercial duct air leakage testing for selected sections. It should also show the system name, drawing area, duct pressure class, seal class where specified, leakage class or code limit, test pressure, and whether the air handler or equipment casing was included.

Commercial projects often express allowable leakage using duct surface area, pressure class, and leakage class. Residential programs often express leakage at 25 Pa against floor area or per system. Those are different records. Do not let a field note blur them together.

The test section selection matters. If the owner, engineer, commissioning agent, inspector, or TAB firm selected representative sections, write that down. If the entire system was tested, say that. If a section was excluded because it was not ready, blocked, unsafe, inaccessible, or outside the test requirement, name the exception before balancing starts.

Record the setup, not just the result

The setup is part of the result. Record the test device, flow-measuring device, calibration status, temporary caps, sealed registers or openings, access doors, smoke or audible leak check if used, damper positions, isolation boundaries, and the test connection point. For residential work, record whether boots or registers were sealed and whether the air handler enclosure was included for the stage being tested.

For commercial DALT, show how the duct surface area was calculated. Attach the takeoff, sketch, or worksheet that connects the tested section to the allowable leakage calculation. A measured cfm value is hard to defend if nobody can reproduce the area or pressure basis.

Photographs help when they show isolation, caps, registers, test rig, gauge reading, leak locations, and repaired joints. A photo of the tester alone does not prove the duct section, pressure, or boundary.

Repairs and retests need their own chain

A failed first test can still lead to a clean handoff, but only if the repair chain is visible. Record the first measured leakage, the pass/fail target, observed leak locations, repair material, repair date, responsible crew, and retest result. If the repair involved mastic, tape, gasket, fasteners, access-panel work, boot sealing, casing work, or duct replacement, the note should say what changed.

Keep repair evidence tied to the same scope. Do not test one section, repair another, and then write passed without showing the retested boundary. If the retest pressure, surface area, or included components changed, the packet should explain why.

If a section remains above the limit, call it a hold or exception. Do not release it to balancing with a note that can be read as a pass.

Release the system to TAB with exceptions visible

The release line should be simple. Released to TAB means the required leakage test scope has passed or the responsible project authority has accepted the result. Limited release means TAB can proceed on named areas while listed sections remain open. Held means balancing should not start for that system or section.

The TAB crew should receive the final leakage report, system list, test boundaries, remaining exceptions, damper/access constraints, and any repair areas that should be watched during airflow testing. If dampers were moved during leakage repair, note whether they were returned to the intended pre-balance position.

That handoff prevents the final balance report from becoming the first place where a leakage problem is discovered.

Minimum packet

Use the project, TAB, commissioning, or code form first. Add a short field packet only where it makes the leakage result reviewable.

Before balancing checklist

• Confirm the leakage test requirement and acceptance basis are identified.
• Confirm the system, section, and test boundary match the drawings and specification.
• Confirm the test pressure, leakage class or code limit, and allowable leakage calculation are attached.
• Confirm openings, boots, registers, caps, access doors, dampers, and included equipment are documented.
• Confirm test equipment and calibration status are recorded.
• Record the first measured leakage and pass/fail result.
• Record leak locations, repair method, responsible crew, and repair date when the first test fails.
• Retest the same boundary or document why the boundary changed.
• Send the final report and exceptions to the TAB or commissioning lead.
• Write the final status: released to TAB, limited release, or held.

Weak and strong leakage notes

Weak note: duct leakage passed, ready for balance.

That note does not show the system, section, test pressure, allowable leakage, measured leakage, equipment, calibration, sealed openings, witness, repair chain, or release authority.

Stronger note: AHU-2 supply duct, levels 3 east and 4 east, tested as the owner-selected representative section for pressure class shown on M-402. Duct surface area worksheet attached. Test openings capped, access doors closed, VAV connections sealed at test boundary, and dampers left in pre-balance position. Test fan and manometer calibration recorded. First test exceeded allowable leakage; leaks marked at two transverse joints and one access door. Sheet metal crew repaired with approved sealant and gasket work. Retest at specified pressure passed. Report sent to TAB and commissioning lead. AHU-2 east sections released to TAB; west riser remains held pending separate test.

The stronger note is useful because the balancing crew can see exactly what is released, what remains held, and what evidence supports the release.

Common mistakes

The first mistake is writing only a measured cfm number. Without surface area, test pressure, and allowable limit, the number does not prove pass or fail.

The second mistake is changing the test boundary between fail and retest without saying so. That creates a record that cannot be compared.

The third mistake is starting TAB while leakage repairs are still open. Once dampers are adjusted, it becomes harder to separate leakage, balancing, and control problems.

The fourth mistake is hiding exceptions inside email. The TAB report should not have to discover that one riser, outdoor duct run, or return section was never released.

Specification and safety limits

This field note is not a duct leakage test procedure, TAB standard, code interpretation, commissioning approval, or authority to accept an HVAC system. Qualified personnel, adopted codes, project specifications, referenced standards, test agency procedures, engineer direction, owner requirements, and AHJ requirements control the work.

Do not use this checklist to bypass lockout, ladder or lift safety, fall protection, confined-space rules, electrical safety, rotating equipment safety, access-panel replacement, ceiling work controls, dust controls, or site-specific safety procedures. The record helps preserve the decision. It does not replace the decision authority.

Sources checked

• DOE Building Energy Codes Program, duct leakage testing FAQUsed for rough-in, post-construction, 25 Pa, register sealing, and air-handler-inclusion context.
• Building Science Education, HVAC duct leakage testingUsed for total leakage, leakage-to-outdoors, equipment/components, code context, and training scope.
• SMACNA, Air Duct Leakage AppUsed for leakage class, test pressure, duct surface area, allowable leakage, and pass/fail mark themes.
• ASHRAE, Addendum cq to Standard 90.1-2007Used for commercial duct leakage testing concepts including pressure class, outdoor ducts, representative sections, and allowable leakage formula context.
• ENERGY STAR, National Rater Field ChecklistUsed for per-system leakage assessment, rough-in/final examples, and visual verification allowance context.
• NEBB, Duct Leakage Testing presentationUsed for section selection, surface-area calculation, opening sealing, pressure testing, measured flow, and comparison-to-standard themes.
• NEBB, TAB specification appendixUsed for TAB readiness, mechanical-work-complete expectations, calibration/report context, and deficiency reporting.
• NEBB, Testing, Adjusting and Balancing CertificationUsed for TAB definitions around measuring, documenting, adjusting, and balancing HVAC system performance.

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