What is air permeability testing?

Testing for air permeability is an important part of ensuring a new build meets certain regulations. The results of the test will significantly impact the EPC rating of the property. In this article, we’re going to provide some background information on air permeability testing and provide useful tips to ensure your building can remain as airtight as possible.

Air permeability regulations

Typically, building regulations stipulate that new properties should achieve air leakages in the region of 5m3/hm2 or less. This figure represents air leakage per hour/m2 area, and is considered the general “fail or pass” result an air engineer will consider. It highlights the level of air that is being pulled into a building by leakage when a fan is operational at 50 Pascals.

Air leakage which is uncontrolled

It is important to understand that such a test is designed to check for uncontrolled air leakage. It does not take into account extractor fans, trickle vents or ventilating systems. Prior to testing, controlled sources of ventilation should be sealed or taped up. This is because the purpose of air permeability testing helps to identify cracks or gaps in the infrastructure of the dwelling.

Air permeability certification

Some schemes go beyond building regulations. For example, a standard known as the Passivhaus standard stipulates that new builds should reach no more than 0.6 air changes in an hour. Testing can occur at any moment during the construction process, although it is usual for air permeability testing to be performed in the end stages of the project. This is usually before SAP calculations are made and an Energy Performance Certificate is issued.

In residential builds, air permeability test results are passed to a designated SAP assessor. This assessor will update any calculations, acknowledge a “pass” rate is achieved and develop the final report along with an EPC rating.

Does air permeability affect SAP rating?

The SAP rating is largely affected by air permeability. This is because high levels of permeable air will impact negatively upon the energy performance of a building. SAP assessors generally set air permeability targets between 5-10m3/hm2.

While this is reasonably easy to achieve, sometimes targets could need to be potentially lower. This is because the dwelling could otherwise struggle to meet targets on emissions, and low air permeability could compensate in other areas (from poor design, poor construction or external factors that are deemed out of the control of the developer).

Air permeability tips

Over the course of testing a huge number of building projects for air permeability, the team at Airtight Testing Staffordshire has generated some top tips to ensure the best possible results. These include:

1) Develop an air permeability strategy from the beginning
Outline your target early and have discussions before the construction phase. Ensure all members of your team understand the importance of an airtight build. Project managers may also want to appoint an “air permeability expert” to coordinate between all tradespersons, architects and consultants.

2) Perform inspections at each stage of the build
Try to implement an air permeability inspection scheme throughout construction. This will ensure that air barriers remain uncompromised by poor workmanship. Failures that go unnoticed could lead to costly remedial work further down the line – so ensure leakage is kept to a minimum, and avoid things like cavity wall breaches.

3) Be careful with plaster
Plasterboard can lead to problems. Missed leaks within the block or brickwork have potential paths from behind the plaster to the wall and floor junction and other vulnerable areas such as wall sockets. Again, this can be costly to put right once the plaster has been put in situ.

4) Seal pipework
Supply and waste pipework should be sealed at every point where walls and floors are penetrated. Use high-quality gunned sealants, you can also use expanding foam, as this can and approved flexible foams which have been tested for airtight application.

5) Take extra care with light fittings
Ensure that light fittings and pull cords are adequately sealed. Always choose airtight fittings where possible, or alternatively install airtight boxes over the fitting within the ceiling void.

Find out more about air permeability testing

If you require air permeability testing in Staffordshire and surrounding areas, or if you would like to discuss your project in detail with us, simply contact us or give us a call today. Our experts will be happy to offer advice on any permeable air testing queries you may have.