Airtightness Testing

Professional Assessments

At Airtightness UK, airtightness testing is what we do. We have extensive experience carrying out fast, efficient air permeability testing on residential and commercial projects across the UK.

Our practical construction knowledge and testing experience allow us to identify air leakage issues quickly and efficiently, helping our clients achieve the required result on the day of the initial test wherever possible. Rather than returning for repeated re-tests, we are regularly invited back for future projects because clients value our reliable service, practical approach, and ability to help deliver compliant results efficiently.

What is Airtightness?

 Airtightness refers to how well a building prevents uncontrolled air leakage through gaps, cracks, and joints within the building envelope. The building envelope includes walls, floors, roofs, windows, doors, and all junctions and service penetrations that separate the conditioned internal environment from the outside air. 

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Good airtightness does not mean a building cannot breathe. Instead, it means unwanted and uncontrolled air movement is reduced so that ventilation can be properly managed through designed ventilation systems such as extractor fans, background ventilators, or MVHR systems.

Uncontrolled air leakage can occur through:

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• Gaps around windows and doors

• Service penetrations for pipes and cables

• Loft hatches

• Floor-to-wall junctions

• Around sockets and switches

• Poorly sealed membranes or plasterboard junctions

• Structural junctions and construction gaps

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Excessive air leakage can lead to:

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• Higher heating and cooling costs

• Reduced energy efficiency

• Draughts and occupant discomfort

• Increased heat loss

• Condensation and moisture issues

• Reduced performance of ventilation systems

• Difficulty achieving Building Regulation compliance

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Airtightness is particularly important in modern construction and retrofit projects where energy efficiency standards are increasingly demanding. Improving airtightness helps buildings perform more efficiently while supporting lower carbon emissions and improved occupant comfort.

Airtightness Testing

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An airtightness test, also known as an air permeability test or blower door test, measures the amount of uncontrolled air leakage through a building. The test is carried out using calibrated blower door equipment and a digital manometer to pressurise or depressurise the property while airflow readings are recorded.

The measured airflow is used to calculate the building’s air permeability, typically expressed as:

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• m³/(h·m²) at 50 Pascals

This result indicates how much air passes through the building envelope under a standardised pressure difference.

During testing, leakage paths can often be identified using:

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• Smoke testing

• Thermal imaging

• Physical inspection

• Airflow detection techniques

Typical leakage areas identified during airtightness testing include:

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• Window and door perimeters

• Loft hatches

• Service penetrations

• Pipework and duct penetrations

• Behind kitchen or bathroom boxing

• Floor edges and thresholds

• Ceiling penetrations and downlights

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Why Airtightness Matters

Improved airtightness can provide:

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• Reduced energy bills

• Improved thermal comfort

• Better building performance

• More effective ventilation control

• Reduced draughts

• Lower carbon emissions

• Improved SAP calculations

• Compliance with Building Regulations

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We provide Airtightness testing for

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• New build dwellings

• Commercial buildings

• Retrofit projects

• Passivhaus projects

• Social housing programmes

• Energy performance compliance​

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Modern construction increasingly focuses on achieving a balance between airtightness and controlled ventilation to ensure buildings remain energy efficient, comfortable, and healthy for occupants.

We are the experts in Airtightness. We are very experienced in fast efficient testing. We can identify issues quickly and efficiently. This helps our customers achieve the result they require on the day of the first test. We dont get call back for re-tests, we get call backs for the next project.