Air Tightness Testing Services in the UK
Air Tightness Testing Across the UK
At APT Sound Testing, we provide comprehensive air tightness testing services throughout the United Kingdom. Our experienced team works on projects of all sizes — from single residential dwellings to large-scale commercial developments.
We are proud to be one of the few UKAS-accredited companies qualified to carry out both Air and Sound Testing in full compliance with UK Building Regulations and Standards. This accreditation allows us to deliver combined Air, Sound, and Vent Testing packages during a single site visit — saving our clients time, reducing costs, and improving on-site coordination. Importantly, we never subcontract our testing work; all services are delivered by our fully trained in-house engineers.
Why Air Testing Matters
Since 2006, air testing has been a legal requirement in England and Wales under Part L of the Building Regulations. Its importance continues to grow as the construction industry focuses on reducing carbon emissions and improving energy efficiency.
Part L defines air leakage as the uncontrolled flow of air through gaps and cracks in a building’s structure — commonly known as draughts. When buildings lose energy through their fabric, this contributes to the building emission rate (BER). To meet regulatory approval, new developments must achieve strict air permeability targets:
- Standard dwellings: Typically 5.0 m³/hr/m²
- Commercial buildings: Often around 3.0 m³/hr/m² or lower
Improving airtightness reduces unnecessary heat loss, lowers energy consumption, and contributes to greener, more sustainable buildings.
The Risks of Poor Air Tightness
Air infiltration and exfiltration can create a range of issues:
- Energy Loss: Escaping air must be replaced and conditioned, increasing heating and cooling demands.
- Condensation & Mould: In winter, warm moist air entering cold cavities can cause condensation, mould growth, and structural damage.
- Uncomfortable Draughts: Uncontrolled airflow can make both residential and commercial properties unpleasant to occupy.
- Indoor Air Quality Concerns: Air leakage can allow polluted external air to enter buildings, particularly in locations near busy roads, fuel stations, restaurants, or waste storage areas.
We have previously tested buildings with air leakage rates as high as 25 m³/hr/m² — far above acceptable levels. After identifying and sealing leakage paths, the same buildings were brought below 5 m³/hr/m², dramatically improving comfort and performance.
Our Consultancy & Pre-Completion Support
Achieving compliance starts at the design stage. We offer air tightness consultancy and detailed design reviews to help ensure your project meets its targets first time.
Our support includes:
- Early-stage air leakage line design advice
- Pre-completion inspections
- On-site testing for building control sign-off
- Weekend and out-of-hours testing services to minimise disruption
To avoid costly failures, we strongly recommend considering air barrier design as early as possible in your project.
Combined Air & Sound Testing Packages
Because our multi-skilled engineers are UKAS accredited for both disciplines, we offer significant savings through combined testing packages. Our popular “3-Step Pre-Completion Package” allows clients to avoid employing multiple contractors, simplifying project management and improving efficiency.
By conducting both tests on the same day in a structured and coordinated manner, we help streamline site operations and reduce downtime.
What Is a Blower Door Test?
Air tightness testing is carried out using blower door equipment, which measures:
- The airflow entering or leaving a building
- The pressure difference across the building envelope
This data helps estimate energy performance under various weather conditions and supports equipment sizing and energy consumption predictions.
Using blower door and smoke testing, we can accurately locate leakage paths. While some issues stem from large, obvious gaps, more often it is multiple smaller leaks that contribute most significantly to poor results. Our experienced engineers quickly identify and document these areas so corrective action can be taken efficiently.
Protecting Energy Performance and Occupant Health
Excessive air leakage can:
- Increase heating and cooling costs
- Cause condensation, mould, and rot
- Reduce occupant comfort
- Allow outdoor pollutants to enter the building
A well-designed and properly installed air barrier is essential for controlling both air quality and air quantity within a building.
Work With Experienced Air Tightness Specialists
APT Sound Testing has extensive experience delivering thousands of successful air tightness tests across London and the wider UK. Our in-depth knowledge of Approved Document L ensures your development is supported from concept through to completion.
By working collaboratively with clients throughout the design and construction phases, we help identify practical solutions to minimise air leakage and achieve compliance first time.
If you are preparing for an upcoming test, we recommend reviewing an air tightness checklist to ensure your project is ready.
For friendly, expert advice tailored to your development, contact our team today on 01525 303905 or via our online contact form to discuss your air testing requirements.