The Airtightness Challenge Facing Modern Construction: Why Blockwork Alone Is No Longer Enough
The construction industry is changing.
Since the introduction of the 2022 updates to Part L Building Regulations, there has been a significant shift towards improved energy efficiency, reduced carbon emissions, and higher-performing buildings.
While many builders, developers, and contractors continue to use traditional construction methods, the reality is that modern building regulations are placing greater emphasis on airtightness than ever before.
The question is no longer whether a building can be constructed using familiar methods. The question is whether those methods can consistently deliver the performance standards that modern regulations demand.
As the industry moves towards lower-carbon buildings and future performance targets, relying solely on blockwork as an airtightness strategy could become one of construction's biggest challenges.
What Changed in the 2022 Building Regulations?
The 2022 updates to Part L of the Building Regulations were designed to improve the energy efficiency of new homes and buildings across the UK.
The changes introduced stricter requirements aimed at reducing carbon emissions and improving the overall performance of the building fabric.
To achieve these targets, greater attention is now being placed on reducing uncontrolled heat loss and improving the airtightness of the building envelope.
In simple terms, buildings are expected to perform better than they did under previous regulations.
This means that airtightness is no longer a secondary consideration. It has become a key part of modern construction.
The 2022 Regulations Didn't Just Change Energy Targets
The 2022 updates introduced stricter thermal performance requirements for walls, floors, roofs, and openings. To achieve these improved standards, wall constructions have evolved significantly.
Many builders are now moving towards wider cavities, improved insulation specifications, and aerated thermal blocks to help reduce heat loss and thermal bridging. Traditional 100mm cavity constructions are becoming less common, with cavity widths of 125mm, 140mm, and even 150mm increasingly being specified to achieve compliance.
The focus is no longer simply on building a wall. The focus is on building a wall that performs.
As thermal performance improves, attention naturally shifts towards another major source of energy loss: air leakage.
Better Thermal Performance Exposes Airtightness Weaknesses
Modern wall constructions are far more thermally efficient than previous generations of buildings.
Aerated thermal blocks, wider cavities, and improved insulation all help reduce heat transfer through the building fabric. Thermal bridging around floor junctions, openings, and wall connections is also receiving greater attention than ever before.
However, while thermal performance has improved dramatically, air leakage remains one of the most overlooked areas of construction.
A highly insulated wall can still underperform if uncontrolled air movement is allowed through junctions, service penetrations, blockwork interfaces, and other areas within the building envelope.
As buildings become more thermally efficient, airtightness becomes increasingly important because uncontrolled air leakage can undermine the benefits of the insulation and fabric improvements designed into the building.
The Problem with Relying on Blockwork Alone
For many years, blockwork has been viewed as part of the airtightness strategy within residential and commercial construction.
However, blockwork alone was never designed to function as a complete airtight barrier.
Small gaps, mortar inconsistencies, service penetrations, junctions, and interfaces between building elements can all create pathways for uncontrolled air leakage.
Historically, these weaknesses may not have been considered significant.
Today, as performance expectations increase, these details matter more than ever.
A building can appear complete while still allowing significant amounts of uncontrolled air movement through the building envelope.
This can lead to higher energy consumption, reduced thermal performance, increased heating demand, and greater risks associated with moisture movement within the structure.
Airtightness Is Becoming a Key Part of Compliance
The 2022 regulations introduced a greater focus on proving that buildings perform as designed.
Builders are now required to provide photographic evidence of key construction stages, including insulation installation, cavity barriers, and critical junction details. This shift reflects a growing industry emphasis on verification and accountability rather than assumptions.
At the same time, modern airtightness standards require a clear strategy for controlling air movement through the building envelope.
While blockwork remains an important structural element, relying on blockwork alone as the primary airtightness layer is becoming increasingly difficult to justify on higher-performing buildings.
This is why many projects are incorporating wet parge coats, plaster systems, and liquid-applied airtight membranes to create a continuous and measurable airtight barrier.
The Growing Role of Wet Parge Coats and Liquid-Applied Membranes
To improve airtightness performance, many contractors and developers are now turning to wet parge coats and liquid-applied airtight membranes.
These systems are designed to create a continuous airtight layer directly onto the substrate, helping to reduce uncontrolled air leakage throughout the building envelope.
Unlike traditional methods that rely on multiple materials and interfaces, liquid-applied systems provide a seamless solution that can easily accommodate junctions, penetrations, and complex detailing.
This helps improve consistency while supporting modern airtightness targets.
As building performance becomes increasingly important, these approaches are becoming a key part of modern construction strategies.
How Passive Purple Supports Modern Airtightness Requirements
Passive Purple is a liquid-applied airtight vapour control membrane developed to help create a continuous internal airtight layer across the building envelope.
Applied directly to substrates including blockwork, concrete, timber, sheathing boards, and plasterboard, Passive Purple forms a seamless membrane that helps reduce uncontrolled air leakage while supporting moisture management within the structure.
Its liquid application allows it to easily adapt around service penetrations, awkward junctions, and difficult detailing where traditional airtightness solutions can often struggle.
As regulations continue to evolve and performance expectations increase, solutions such as Passive Purple provide a practical way to support a more robust and measurable airtightness strategy.
If you'd like to learn more about airtightness, Part L Building Regulations, or how Passive Purple can support your next project, contact the Intelligent Membranes team today.