Air Tightness Testing

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Air Tightness Testing in UK

Air tightness testing measures the air permeability of a building and identifies uncontrolled air leakage through the building envelope. Effective air tightness is an important component of energy-efficient building design and is required for many new buildings under the Building Regulations.

Our team provides on-site air tightness testing for residential and commercial buildings throughout the UK, together with design-stage consultancy to help project teams achieve the required performance.

Building Air Permeability Testing

An air tightness test uses controlled pressure to assess the amount of air escaping through gaps and leakage paths in the building envelope. The resulting air permeability figure provides an objective measure of the building’s airtightness.

Testing can identify areas where detailing, workmanship or junctions may be contributing to excessive air leakage.

Part L Compliance

Air permeability is an important consideration under Part L of the Building Regulations. Meeting the required performance target can help demonstrate compliance while also supporting improved energy efficiency.

Our testing services can be incorporated into the wider energy compliance process alongside SAP and SBEM calculations where required.

Design-Stage Air Tightness Consultancy

Achieving good airtightness is easier when it is considered during design and construction rather than left until completion. We can provide advice on building envelope detailing, likely leakage points and practical measures to improve performance.

This early input can help contractors identify potential issues before they become difficult or expensive to correct.

Residential and Commercial Testing

We undertake air tightness testing for a range of new-build and refurbishment projects, including residential developments, commercial buildings and other building types where air permeability performance needs to be established.

Following testing, we provide clear reporting of the results and can advise on remedial measures where performance does not meet the required target.

Supporting Energy Efficiency

Reducing uncontrolled air leakage can help reduce heat loss and improve the effectiveness of mechanical ventilation systems. Air tightness should therefore be considered as part of the wider approach to building energy performance rather than as a standalone compliance exercise.

Our Air Tightness testing Experts Are Here To Help

The Syntegra Group offer on-site air tightness testing throughout the UK for commercial and residential buildings. Our team also provide design stage Air Tightness consultancy.

Additionally, we offer SAP and SBEM calculations as well as post completion certification and energy performance certificates.

Achieving improved air tightness is a key factor in building contractors meeting the Government’s targets for reduced carbon emissions and improved energy efficiency.

So if you need an expert that is friendly, professional and can help you from start to finish why not ring today on 0330 053 6774.

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FAQS

Question: What is air tightness testing?

Answer: Air tightness testing, also known as air permeability or blower door testing, measures the rate at which air leaks through the fabric of a building. A calibrated fan is fitted to an external door, the building is pressurised and depressurised, and the airflow required to maintain a pressure difference of 50 Pascals is measured. The result is expressed as air permeability in m³/(h·m²) at 50 Pa.

Air leakage is a major source of heat loss, and testing is required under Building Regulations Part L to demonstrate that the building meets its design air permeability.

Question: When is air tightness testing required?

Answer: Under Approved Document L 2021, every new dwelling must be tested, replacing the previous sampling approach. All new non-domestic buildings must also be tested, with limited exemptions for very small buildings and large extensions. Testing is also required for Passivhaus certification, for BREEAM Ene 01 modelling, for some funders and warranty providers, and for Part L compliance of buildings where the design relies on a low air permeability value.

Question: What air permeability is required?

Answer: The Part L 2021 limiting value for new dwellings and non-domestic buildings is 8 m³/(h·m²) at 50 Pa, but the design air permeability used in the SAP or SBEM calculation is typically much lower, often 5 or below, and the test must achieve the design value or the calculation must be revised. Passivhaus requires 0.6 air changes per hour at 50 Pa, which is considerably more demanding. Buildings below 1.5 m³/(h·m²) require mechanical ventilation to maintain indoor air quality.

Question: How is an air tightness test carried out?

Answer: The tester seals intentional openings such as trickle vents, extract fans and flues, installs the blower door fan and measures the envelope area and volume. The building is tested at a series of pressure differences, both pressurised and depressurised, in accordance with ATTMA Technical Standard L1 or L2 and BS EN ISO 9972. Results are calculated and a certificate issued for submission to building control. Tests typically take one to three hours per dwelling or unit.

Question: What are common causes of air tightness failure?

Answer: Common leakage paths include gaps around windows and doors, service penetrations through walls and ceilings, unsealed junctions between floors and walls, loft hatches, recessed downlights, behind bath panels and kitchen units, and gaps in dry lining. Smoke pencils and thermal imaging during the test can locate leakage so that it can be sealed and the building retested.

Question: How can a building be designed to pass air tightness testing?

Answer: Achieving good air tightness depends on identifying a continuous air barrier line on the drawings, detailing every junction and penetration, selecting appropriate membranes, tapes and sealants, briefing the site team and inspecting before the air barrier is covered. An air tightness strategy prepared at design stage and a pre-test inspection significantly improve the chance of a first-time pass.

Question: Why choose Syntegra Group for air tightness testing?

Answer: Syntegra Group’s ATTMA-registered testers provide air tightness testing for dwellings, apartments, commercial and education buildings and Passivhaus projects across the UK, with certificates accepted by all building control bodies. We use calibrated equipment and follow ATTMA and BS EN ISO 9972 methods.

As Part L assessors and Passivhaus designers, we also help clients set realistic design targets, prepare air tightness strategies and identify leakage during testing so that remedial work and retesting are minimised.