What Is Air Tightness Testing and Why Does It Matter?
In today’s drive toward energy-efficient buildings, air tightness testing has become essential. Whether you’re constructing a new home, extending an existing property, or managing a commercial development, understanding what air tightness testing is—and why it matters—is crucial.
At Assessment Hive, we help clients across the UK meet energy compliance requirements with fast, reliable testing and expert advice.
✅ What Is Air Tightness Testing?
Air tightness testing (also known as a blower door test) measures how much uncontrolled air leakage occurs through gaps, cracks, and openings in a building’s envelope.
The process involves:
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Sealing the building
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Installing a temporary fan in a doorway
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Pressurising the building
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Measuring how much air escapes or enters
The result is recorded in m³/h·m² at 50 Pascals, known as air permeability. Lower values indicate better air tightness, which translates to improved energy performance.
🏡 Why Is Air Tightness Testing Required?
1. Part L Building Regulations Compliance
Air tightness testing is mandatory for most new dwellings in England and Wales, under Approved Document Part L. It confirms whether your building meets the minimum energy efficiency standards.
→ Learn more about Part L compliance
2. Impact on SAP Calculations and EPC Ratings
The test result directly affects your SAP Calculations, which in turn influence your Energy Performance Certificate (EPC) rating. A poor air permeability result can increase energy demand and potentially cause a fail on your SAP assessment.
🔗 Read our full guide: SAPs Calculations
3. Energy Savings & Lower Bills
Uncontrolled air leakage leads to heat loss, cold draughts, and higher heating costs. By sealing gaps and achieving a better air test result, you can:
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Improve insulation performance
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Reduce heating bills
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Increase thermal comfort for occupants
4. Better Indoor Air Quality
When paired with proper mechanical ventilation, air tightness improves air quality by controlling how outside air enters the building — particularly important in airtight modern homes.
🔍 Where Do Air Leaks Usually Occur?
We frequently identify air leakage at:
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Window and door frames
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Loft hatches and roof junctions
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Pipe penetrations and service ducts
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Electrical outlets on external walls
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Wall-to-floor and wall-to-roof junctions
🛠️ When Should the Test Be Done?
Air tightness testing should be completed:
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Near the end of construction, when the envelope is sealed
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Before final decorations, allowing time to fix any failures
We recommend early preparation and pre-test advice to avoid delays or costly remediation.
💡 Why Choose Assessment Hive?
At Assessment Hive, we make the process simple:
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Fully qualified and experienced testers
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Competitive prices for domestic & commercial builds
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Same-day results and certification
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Expert advice to help you pass first time
📞 Get in Touch
If you need an Air Tightness Test for a property in Hertfordshire, Kent, Essex, London or anywhere else in the UK – Assessment Hive can help.
📞 Call us on 020 7183 3240
📧 Email us at [email protected]
📝 Request Instant Quote → Click Here
