You are preparing a house for a blower door test and want to find leaks while they are still accessible. The test measures enclosure air leakage under an imposed pressure difference. Plan diagnostic testing while repairs are accessible. Schedule the required final test under the accepted project procedure.
PNNL describes a blower door as a fan-and-measurement setup that pressurizes or depressurizes the house. The result puts a number on leakage. It does not, by itself, identify every repair or certify the entire building’s performance.
Read the airflow and air-change results
An enclosure test measures airflow through the building enclosure at specified test conditions. PNNL’s enclosure leakage guide describes results at a pressure difference of 50 pascals. The report may express that airflow as CFM50 and normalize it using enclosure volume as ACH50.
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| Report term | Meaning | What to check |
|---|---|---|
| CFM50 | Cubic feet of airflow per minute at 50 pascals | Correct pressure, setup, and reported units |
| ACH50 | Air changes per hour at 50 pascals | Correct enclosure volume and calculation |
| Test boundary | The enclosure included in the measurement | Agreement with the house’s intended air barrier |
| Test preparation | How openings and systems were configured | Compliance with the required test procedure |
| Acceptance criterion | The project’s applicable limit or target | Code, program, or contract basis |
PNNL’s air-leakage metrics resource distinguishes several ways of reporting leakage. Do not compare results that use different metrics without understanding the conversion and inputs. Ask the tester to identify exactly what is being reported.
ACH50 uses CFM50 multiplied by 60, divided by enclosure volume in cubic feet. That is the PNNL calculation. The 60 converts minutes to hours; ACH50 describes test conditions rather than ordinary outdoor-air exchange throughout a day.
Separate air sealing from insulation
Insulation reduces heat flow through assemblies. Air sealing addresses air movement through gaps and connections. DOE’s air-sealing guide explains why insulation alone does not necessarily block airflow.
Use the insulation-grade guide to review insulation installation separately. A good blower door number does not establish complete insulation coverage or every thermal detail. Use both visual checks and test results. Neither replaces the other.
Ask the tester what additional diagnostics are useful for a suspected issue. PNNL describes smoke and infrared observations during testing as ways to help locate leakage. Ask what the test conditions and method allow the tester to confirm.
Do not ask for a broad “energy pass” when the contracted service is an enclosure leakage test. Specify the required measurements, diagnostic work, and report.
Agree the boundary and test procedure early
Identify the intended air barrier on the construction documents. Check that it continues through walls, floors, ceilings, and the connections between them. Ask the designer and tester to resolve ambiguous areas before construction covers them.
Discuss which garages, attics, crawl spaces, and attached spaces are inside or outside the test boundary. Have the tester explain which spaces belong in the measured enclosure. Use the same boundary when checking reported volume and HVAC assumptions.
Confirm the applicable code, amendments, and any voluntary program requirements. For North Carolina, start with OSFM’s current-code resources and the permit authority. Do not apply a national article’s pass threshold without checking the actual project.
Put the agreed test method, accepted report, and required tester qualifications into the scope. Ask who books the test, who prepares the house, and who authorizes corrections. Assign those jobs before scheduling final inspection.
Choose the test stages around access
Ask the tester when the house will be sufficiently complete for a useful diagnostic test. Plan that visit early enough to reach likely problem areas. Then identify what completion stage the required final test needs.
Adapt these steps to your project and local inspection schedule:
- Review the air-barrier plan and trade responsibilities before rough-in.
- Walk transitions and penetrations while access remains available.
- Perform an agreed diagnostic test when the boundary can be tested.
- Assign and complete identified corrections.
- Recheck repairs as needed before access closes.
- Complete the required final test and retain its report.
Coordinate those stages with rough-in and insulation inspection. Confirm the local inspection sequence independently. A diagnostic visit is useful only if the responsible trades can act on its findings.
Assign air-sealing work to each trade
Mark on a plan or list where each trade must complete air-sealing work. Do not leave every gap under a general “insulator to seal” note. Ask each contractor to identify what its scope includes and what another trade must complete.
Assign the following work:
Scroll to read all columns.
| Work area | Responsibility to assign |
|---|---|
| Framing transitions | Continuous air-barrier backing and connections |
| Windows and doors | Connection between the unit and surrounding air barrier |
| Plumbing and electrical penetrations | Compatible sealing and responsibility after later changes |
| HVAC and ventilation openings | Intended openings, sealing interfaces, and test configuration |
| Insulation work | Specified air-sealing scope and access requirements |
| Access panels and hatches | Completed closure and sealing details |
Ask the designer for the specified materials and assembly details. DOE identifies common air-sealing locations, but a general guide cannot select the right material for every fire, moisture, or compatibility condition.
After a trade adds or changes a penetration, require it to report the location. Have the assigned party restore the accepted detail. Track the correction until it is complete, before the area is covered.
Prepare the house under the required test method
Have the tester provide a readiness checklist for the required method. Assign someone to confirm each item before arrival. Ask the tester to document how intentional openings and mechanical systems are configured.
Let the qualified tester manage testing safety. PNNL’s enclosure guidance addresses combustion-appliance and depressurization concerns. Tell the tester about installed combustion equipment and other relevant site conditions before the visit.
Avoid temporarily sealing a defect merely to obtain a number. Ask whether each preparation step belongs to the prescribed method. Keep setup notes with the report so anyone reviewing the result knows how the house was tested.
Assign repairs and recheck a poor result
Ask the tester to distinguish a valid measured result from a setup or reporting problem. Check the test boundary, volume, units, and required limit or target. Then request a location-based correction list from the diagnostic work.
Assign each repair to a contractor with a completion date. If it is unclear how to seal a connection, ask for the specified repair detail. Recheck the repairs and keep the final result. Delivering sealant does not close the issue.
Connect the result with Manual J planning. ACCA’s load-calculation overview includes infiltration and ventilation inputs. Ask the HVAC designer whether the measured result requires review of the design assumptions.
Include planned ventilation in the review. DOE’s air-sealing guide treats ventilation and safe appliance operation as companion considerations. Ask the responsible designer to resolve those needs rather than relying on accidental leakage.
Where Cercha fits
Cercha trade search helps you identify insulation and HVAC contacts for the enclosure handoff. Messages lets you discuss the scope, and portfolios provide examples of related work. Confirm testing credentials, methods, and correction responsibilities directly with the project team.