Air Tightness Testing

Also known as air leakage testing, air infiltration testing, air pressure testing or air permeability testing, is a test required by the Part L of the Building Regulations as part of an overall energy performance assessment of a building. Air leakage is calculated as cubic metres of air leakage per hour per square metre at 50 Pascals (or 4Pa for Pulse Testing). But what does this actually mean?

What is Air Leakage?

Air leakage can occur through gaps and cracks in the fabric of the building envelope, allowing conditioned (heated or cooled) air to escape, which consequently driving up heating/ cooling bills and contributing to potentially to carbon dioxide emissions, in the form of mains gas or non-renewable electricity sources.

How long does an Air Test take?

Typically the test takes between twenty minutes to a couple of hours. This all depends of the size of the building, the test locations, the ability to create stable pressure in the building and unfortunately the controllable influence of the British weather.

Typically a test is carried out by a single engineer using a UKAS calibrated blower door system. The system is essentially a fan mounted within a canvas, that’s installed within an external door or window, controlled by a fan speed controller, and a number of tubes connected to a multi-channel manometer, which is read and inputted into a software to generate a result.

During this time other trades can remain within the building so long as the external envelope remains closed (external doors and windows) and internal doors open.

Pre-test Preparation

The building must be in a state of readiness, with all external doors and windows fitted and operational. Internal doors should be open, and any ventilation systems should be turned off.

Airtightness testing is a government-regulated procedure to measure the amount of air that seeps through gaps and cracks in buildings. It’s a crucial part of building regulations in London, and if you own a residential property or commercial business you need to ensure that you meet these targets.

Air leakage can cause significant heat loss, higher C02 emissions and expensive heating bills. This can be a real pain for homeowners, landlords and businesses so it’s important that buildings are properly sealed in the first place.

We’ll start by carrying out a thorough inspection of your property, ensuring that it’s ready for testing. This includes a full building check, which will include walls, doors, windows and skirting.

Air Test Results and Reporting

The technician will record the results of the test, which will include the air permeability rate (measured in air changes per hour, or ACH), and any areas of the building that failed to meet the required standard. This will be reported on a short-form report – ATTMA Certificate. A full report and Part L photographic evidence can be provided on request. The technician will prepare a written report that includes the test results, any areas of concern, and recommendations for remedial actions. This report must be submitted to the building owner and to the relevant building control authority.

The Air Pressure Testing Standards

In Approved Document Part L1 of the Building Regulations, the process of assessing a building’s air tightness is commonly referred to as Pressure Testing. This methodology, as defined in ATTMA Technical Standard 1, is based on internationally recognized standards like BS EN Standard 13829:2001 and ISO 9972:2015. For new dwellings, as stipulated in Approved Document L1, airtightness tests are mandatory for any new build dwelling or development comprising two or more dwellings/flats, with the number of tests contingent on the development’s size and layout. Compliance with Part L1A necessitates that any tested dwelling achieves an air pressure test result (or air permeability) of 10m³/h/m² or less at a pressure differential of 50 pascals. Similarly, under Approved Document L2, which pertains to new non-dwelling buildings, air permeability tests are also required for new build premises other than dwellings, with the quantity of tests contingent on the development’s size and configuration.

Air Tightness Testing Equipment

As expected, the equipment used for Air Permeability Testing is highly specialized and demands frequent and rigorous calibration to ensure precision. All equipment from Building Compliance Testing is calibrated by a UKAS approved laboratory to guarantee accuracy during on-site tests. Building Compliance Testing is registered with ATTMA, subject to regular audits to uphold high standards and accuracy. If you’re uncertain about whether your development necessitates an Air Permeability Test, Building Compliance Testing can provide guidance. We also offer complimentary, no-obligation quotes at highly competitive rates for projects of all sizes.

Is Your Project Ready For Air Testing?

Check out our Air Permeability Testing site status checklist to see if you are ready – just click here. Free to download.

Your Building Compliance Partner – Air Tightness Consultancy

Whether your requirements is for a domestic retrofit, residential or commercial development, to eco-build passivhaus testing, Building Compliance Testing can support you from concept to completion by offering a one-stop-service service:

design reviews – site inspections – pretesting – smoke diagnostics – site management training and education

Learn more about our Air Tightness Consultancy by clicking here.

Testing and ATTMA Certificate for as little as £45+VAT

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We don’t just offer Air Testing. Bespoke testing and other complimentary services include:

– Part L Compliance

– Smoke Shaft Testing for Automatic Opening Ventilation (AOV)

– Room Integrity Testing

– Smoke Testing

– Multi-fan Commercial Testing

– Existing Buildings Testing

– Air Tightness Design Reviews

– Plenum and Raised Access Testing (RAF) to BG65 Standards

– Passivhaus Testing

– Air Sealing in preparation for Air Tightness Testing

Summary

Air leakage testing, a requirement under Part L of the Building Regulations, assesses a building’s energy performance by measuring the volume of air escaping per hour per square meter at a specific pressure level (usually 50 Pascals). This test helps identify gaps and cracks in the building envelope, through which conditioned air can escape, leading to increased heating or cooling costs and potential carbon dioxide emissions. Conducted using a calibrated blower door system, the test takes approximately twenty minutes to a few hours and involves a fan, manometer, and software to determine results. Building Compliance Testing offers a comprehensive service, including design reviews, site inspections, and training, alongside other services such as smoke testing, air tightness design reviews, and Passivhaus testing, to ensure compliance and energy efficiency in various building types.