Who this guide is for
- Homeowners curious about air-tightness
- People planning energy improvements
- Anyone offered or considering a test
- Readers preparing for an energy audit
What the test does
The test uses a fan in a doorway to change the pressure inside the home, making air leaks easier to detect and measure. It gives an objective read on overall leakage.
It complements, rather than replaces, a broader energy assessment.
Understanding that the test diagnoses rather than fixes keeps expectations realistic, since the value comes from what you do with the results, prioritising the leaks that matter while protecting healthy ventilation.
- A fan changes internal pressure
- Leaks become measurable
- Gives an objective leakage read
- Part of a wider assessment
What results can tell you
Results indicate how leaky a home is overall and, combined with other diagnostics, can help locate where air escapes.
A professional interprets results in context.
Results indicate how leaky a home is overall and, combined with other diagnostics, can help locate where air escapes, but interpreting them in context is a professional's role rather than a do-it-yourself task.
Finding the leaks
Pairing the test with techniques such as thermal imaging or smoke can help pinpoint specific leak paths, guiding where sealing helps most.
Targeted sealing is more effective than guesswork.
Turning results into a plan
Test findings feed into an air-sealing and efficiency plan, prioritising the leaks that matter most while respecting ventilation needs.
Balance air-tightness with healthy ventilation.
Blower door awareness checklist
- 1Understand the test measures overall leakage
- 2Treat it as part of a wider assessment
- 3Have a professional carry out the test
- 4Ask how leaks will be located
- 5Pair with imaging or other diagnostics
- 6Prioritise the most significant leaks
- 7Balance sealing with ventilation needs
- 8Use results to shape an efficiency plan
Common mistakes to avoid
- Treating the test as a fix rather than a diagnostic
- Sealing without locating where leaks actually are
- Pursuing air-tightness while ignoring ventilation
- Interpreting results without professional context
- Assuming one number tells the whole story
When to involve a professional
- The test is carried out by qualified professionals
- Interpreting results is a professional's role
- Air-tightness must be balanced with ventilation
- Results depend on the home and conditions
Frequently asked questions
Questions readers ask about this topic
What does a blower door test measure?
It measures how air-tight a home is by using a fan to change internal pressure, making air leaks easier to detect and quantify. It gives an objective read on overall leakage.
Can I do the test myself?
No. The test is carried out by qualified professionals using specialised equipment, and interpreting the results in context is also their role. This guide is awareness only.
How does it help with sealing?
Combined with diagnostics such as thermal imaging, the test helps locate where air escapes, so sealing can target the leaks that matter most rather than relying on guesswork.
Should I make a home completely air-tight?
Air-tightness must be balanced with healthy ventilation. A professional can help prioritise significant leaks while ensuring the home still ventilates properly.
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