Air Tightness Testing
Air tightness testing—also known as air leakage, air infiltration, or air permeability testing—is a key requirement under Part L of the Building Regulations. It measures how much air escapes through gaps, cracks, and unintended openings in a building’s envelope, expressed in cubic meters per hour per square meter (m³/hr.m²) of the external surface area.
Uncontrolled air leakage leads to significant heat loss, higher energy bills, and increased carbon emissions. That’s why air tightness testing is mandatory for most new build residential and commercial properties, helping ensure buildings are energy efficient, sustainable, and compliant.
Why Choose Building Efficiency Testing Ltd?
- Fully Compliant Testing: All tests are carried out in accordance with ATTMA TSL1 standards for domestic buildings.
- Qualified Engineers: Our testers are registered ATTMA professionals, trained to deliver precise and reliable results.
- UKAS-Calibrated Equipment: We use high-quality, UKAS-calibrated instruments for consistent accuracy.
- Fast Certification: We aim to issue your air tightness test certificate quickly after testing, helping you stay on schedule.
- Flexible Scheduling: We work around your build program to ensure minimal disruption.
Do I Need an Air Tightness Test?
Under Approved Document L of the Building Regulations, air tightness testing is required for:
- All new-build residential dwellings
- All new commercial developments
It is not required for:
- Building conversions
- Extensions to existing properties
- Renovations of existing homes
Even if not legally required, a voluntary air tightness test can help homeowners identify ways to improve energy efficiency, reduce heating costs, and improve comfort.
When Should Testing Be Done?
Testing is typically conducted at the post-second fix stage. To ensure a valid and accurate result, please make sure the following is completed beforehand:
- All service penetrations are sealed
- Trickle vents are installed
- Loft hatch is fitted
- Plumbing systems are filled and sealed
- External door seals are installed
- Electrical outlets are complete
Meeting these conditions ensures you pass the first time and avoid costly re-testing.
Why Air Tightness Testing Matters
Beyond legal compliance, air tightness testing plays a crucial role in creating healthy, comfortable, and sustainable homes. Ignoring air leakage can lead to:
- Damp problems and condensation
- Increased heating bills
- Cold drafts and discomfort
- Lower indoor air quality
For builders and developers, poor air tightness performance can result in unsatisfied tenants, delayed approvals, and even fines for non-compliance with Part L1A.