Air Leakage Testing and Verification: What the Numbers Can Prove

Define the question before turning on the fan

A test may establish a baseline, find large bypasses, verify a program target, compare prework and postwork conditions, or diagnose a particular zone. Those purposes need different preparation and reporting. Write the purpose first so the operator knows what to include and what conclusion the result may support.

PNNL’s enclosure leakage guide describes a controlled pressure test of the building. The reported airflow belongs with the test pressure and setup. A bare number such as “1,200 CFM” is incomplete.

Record a reproducible configuration

Document which doors and windows were closed, which interior doors were open, how fireplace openings, exhausts, outdoor-air ducts, traps, dampers, and combustion equipment were treated, and whether attached spaces were inside the test boundary. Record building volume or enclosure area calculations when the reported metric uses them.

Evidence	What it can support	What it cannot establish alone
Airflow at a stated pressure	Leakage magnitude under test setup	Exact leak locations or insulation quality
Normalized leakage metric	Comparison under the chosen method	Comfort, IAQ, or energy savings by itself
Smoke movement	Local flow direction during test	Natural-condition flow or safe chemical use
Infrared pattern	Surface-temperature differences under conditions	Moisture, missing insulation, or air leakage without corroboration
Zonal pressure	Connection strength between zones	Exact opening geometry or required repair
Pressure pan at register	Duct-zone connection under setup	Duct leakage quantity without the specified test

Baseline and final tests must be comparable

Use the same recognized procedure, boundary, pressure, building dimensions, and configuration. Record equipment identification and calibration status, operator, date, weather, and unusual conditions. If the building changed size or a space moved inside the enclosure, explain how that affects normalized results.

A lower postwork value shows less measured leakage under the recorded setups. It does not prove that every targeted connection was sealed, that moisture will be safe, or that ventilation is adequate. Pair the result with photographs and a closeout inspection.

Diagnostics guide investigation, not blind sealing

Pressure-guided smoke or a theatrical fog method can reveal flow, but protect occupants, alarms, finishes, and sensitive equipment. Infrared work depends on temperature difference, surface properties, wind, solar history, and operator interpretation. Do not drill or fill a cavity solely from one colored image.

Use a leak inventory with location, connected zone, observed method, proposed repair, hazard screen, and outcome. A leak to an attached garage, crawl space, or attic deserves different treatment from leakage between two conditioned rooms.

Tightening changes the operating building

Before work, inventory fuel-burning appliances, exhaust devices, fireplaces, radon systems, attached garages, dryers, range hoods, and required outdoor air. Arrange the applicable combustion and ventilation assessments. After work, commission ventilation and repeat required safety tests under the responsible professional’s procedure.

A useful verification package

1. State test purpose and governing procedure.
2. Draw the tested boundary and calculate referenced dimensions.
3. Record preparation, equipment, weather, and baseline result.
4. Diagnose and photograph priority leakage paths.
5. Screen each repair for water, fire, electrical, pest, and service conflicts.
6. Inspect concealed work before closing assemblies.
7. Repeat the test with comparable setup.
8. Complete ventilation, combustion, and other required commissioning.
9. Report results, uncertainty, changes, unresolved paths, and limitations.

Stop diagnostics around suspect hazardous material, unsafe electrical work, active combustion problems, contaminated spaces, or unstable assemblies. A strong report says what was measured, how, and what remains unknown. It never turns a pressure test into a blanket certification of the building.