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Part L: Air Tightness Testing

  /  Part L: Air Tightness Testing

Part L: Air Tightness Testing

Testing, certification, and consultancy for airtightness and Part L compliance

Delivering compliant, high-performance buildings through airtightness testing.

Air tightness is a key element of the Building Regulations Part L, directly influencing energy performance, heat loss, and overall building efficiency.

MES Building Solutions provides air tightness testing and compliance support, helping residential and commercial projects achieve required targets efficiently. Our approach focuses on early engagement, practical coordination, and reliable testing to minimise risk and avoid delays at completion.

We work closely with contractors and site teams to ensure buildings are prepared for testing, improving first-time pass rates and reducing costly remedial works.

On-site air permeability testing carried out during Part L compliance testing.

Pre-Test Guidance

Advice on construction detailing, sequencing, and site readiness to help achieve air tightness targets efficiently

Air Tightness Testing

On-site testing using calibrated equipment, measuring air permeability in line with regulatory standards

Leakage Identification

Support in identifying key air leakage areas and practical recommendations for improvement where required

Certification & Reporting

Provision of test certificates and documentation to support Building Control sign-off and Part L compliance

Why Air Tightness Matters

Airtightness is critical in reducing heat loss and uncontrolled air leakage, particularly as buildings become more energy efficient.

Effective testing and coordination ensure compliance is achieved without delays and contribute to overall building performance.

Reduced heat loss and improved energy efficiency

Greater certainty in achieving Part L compliance

Lower risk of test failure and retesting costs

Better-performing, more comfortable buildings

Our Air Tightness Testing Process

01

Initial Review

Assessment of project requirements and target air permeability

02

Pre-Test Preparation

Guidance to ensure the building is ready for testing and likely to pass

03

On-Site Testing

Air tightness test carried out in accordance with industry standards

04

Certification & Sign-Off

Issuing of test certificate and support for Building Control submission

Blower door fan installed for air tightness testing under Part L compliance

Preparing for Your Air Test

External doors, windows, and envelope fully installed and sealed

All service penetrations (pipes, ducts, cables) sealed

Trickle vents closed and vents/fans installed or temporarily sealed

Loft hatches, risers, and service voids properly sealed

Drain taps filled and fireplaces/flues sealed where required

Need some more information? See our Guide to Air Leakage Testing.

Related Performance Testing Services

Additional services and guidance on the topic: