DAVID MURRAY, Head of Technical Affairs and Ireland Sales, MEDITE SMARTPLY
In housebuilding, specified insulation values and glazing specifications are relatively straightforward to achieve, if built correctly. Airtightness can often be the crucial aspect that determines whether a building element comfortably meets its targets. It is invisible, can be tricky to achieve, difficult to fix late in the build, and yet fundamental to energy performance and compliance.
Over the past two decades, Ireland’s regulatory framework has raised expectations on airtightness, and pressure testing is now routine in BER assessments. Outcomes today are improving in many projects, though results still vary from site to site. Many homes now perform well above minimum requirements of 5 m3/ hr/m2 @ 50 Pa, With the EU’s mandate for Zero Emission Buildings by 2030, the margin for error is getting tighter.
Failing an airtightness test is not just about the cost of a retest —it is about the time and disruption that follow. Delays on site, extra sealing work, and knock-on scheduling issues quickly become far more expensive than the test itself.
And the costs continue to mount up over the lifetime of the building. In the UK, research indicates that uncontrolled air leakage can account for around 10–50% of a dwelling’s space heating demand, depending on build quality and condition. It is a costly reminder of how crucial airtightness is to both comfort and efficiency: higher energy bills for occupants, less comfort in winter, and boilers and heat pumps working overtime just to keep rooms warm. Designing for airtightness from the outset delivers savings year after year, as well as more reliable performance from heating and ventilation systems.
There is also the question of health and comfort. Draughty buildings feel colder, but simply sealing them without planning for ventilation risks creating new problems. When airtightness is paired with a controlled ventilation system, occupants benefit from cleaner, healthier air and protection against mould and condensation. Far from being a drawback, airtightness becomes the foundation of a consistently comfortable indoor environment.
The most effective way to achieve this outcome is to treat airtightness as part of the building fabric design, rather than an afterthought. That requires design integration and robust materials that perform reliably on site, which is where engineered timber panels such as SMARTPLY AIRTIGHT are making a difference. Certified as airtight by the Passive House Institute, the specialist OSB/3 panel combines structural strength with an integrated vapour control layer, removing the need for separate membranes. Manufactured from FSC-certified timber with no added formaldehyde, it is designed to deliver consistently high results while supporting healthier indoor environments.
We can see the benefits of this in a recent project by developer Citu, which used SMARTPLY AIRTIGHT across 200 Leeds homes built to Passive House principles. The scheme achieved airtightness levels of 0.6 air changes per hour — the best results in the company’s history — while simplifying detailing and reducing the risk of damage compared to traditional membranes.
Crucially, the use of SMARTPLY AIRTIGHT also supported Citu’s wider ambition to create one of the UK’s most sustainable urban neighbourhoods, demonstrating how airtightness contributes not only to compliance but to long-term energy efficiency and community wellbeing. The project shows how timber-based solutions can help developers align construction quality with climate commitments, proving that high performance and large-scale delivery can go hand in hand.
As Ireland looks ahead to the 2030 ZEB standard, the role of airtightness will continue to grow in importance. Builders who integrate robust and reliable solutions into their projects from the outset will reduce risk, protect schedules, and ensure homes that are cheaper to heat, more comfortable to live in, and fully aligned with national climate goals. With innovations like SMARTPLY AIRTIGHT, achieving success no longer needs to be the hardest part of the build.
ABOUT MEDITE SMARTPLY
MEDITE SMARTPLY is part of Coillte, an innovative, sustainably certified Irish forestry and forest products manufacturer. Based in Clonmel and Waterford, Ireland, MEDITE SMARTPLY produces a versatile range of Medium Density Fibreboard (MDF) and Oriented Strand Board (OSB) building products.
To learn more, visit https://mdfosb.com/en/