Guide to Complying with Building Regulations for Cavity Closers
Cavity walls, consisting of two layers of brickwork or blockwork separated by a gap, act as effective barriers that keep moisture out of a building’s interior. Their superior insulation and ability to prevent dampness have changed the way British homes and buildings are constructed. But when windows and doors are added, the gaps around these openings weaken the barrier, allowing heat to escape and moisture to penetrate.
Cavity closers are specifically engineered to address this issue by sealing these wall openings and restoring the integrity of the building envelope. Beyond their practical benefits, cavity closers are critical for complying with all relevant requirements of the Building Regulations, which set the legal standards for safety, efficiency and quality in construction projects.
What Are Building Regulations?
Building Regulations set the minimum standards for the design, construction and alteration of most buildings across the UK, ensuring the safety and wellbeing of people in and around them. Failing to comply with these regulations can lead to serious consequences, such as legal penalties, project delays, costly remedial work and difficulties with selling, renting or insuring properties.
While the core principles of Building Regulations are consistent throughout the UK, the specific requirements are determined by the individual governments of England, Scotland, Wales and Northern Ireland:
- England: Regulations are derived from the Building Act 1984, with practical guidance provided in Approved Documents.
- Wales: Regulations are derived from the Building Act 1984, with practical guidance provided in Approved Documents.
- Scotland: Regulations are governed by the Building (Scotland) Act 2003, supported by Technical Handbooks.
- Northern Ireland: Regulations are based on the Building Regulations (Northern Ireland) Order 1979, accompanied by Technical Booklets.
This article focuses on the regulations in England and Wales, providing insights into how cavity closers contribute to meeting these standards. For information about Scotland and Northern Ireland, refer to their respective technical handbooks and guidance documents.
Relevant Building Regulations and Standards for Cavity Closers
Part L: Conservation of Fuel and Power
Part L of the Building Regulations focuses on improving energy efficiency in new and renovated buildings. One key issue it addresses is cold bridging, which occurs when certain areas of a building allow heat to escape more easily than the surrounding materials. This reduces the overall thermal performance and can also lead to secondary issues such as condensation, staining and mould growth on interior surfaces.
Cavity closers are a really effective way to eliminate cold bridging around doors and windows. When designed with insulated cores or thermal breaks, they seal gaps where heat can escape, maintaining continuous insulation and ensuring compliance with Part L requirements. By reducing the energy needed to heat a building, cavity closers also help lower carbon emissions and contribute to more sustainable construction practices.
Part B: Fire Safety
Part B of the Building Regulations ensures that buildings are designed to limit the spread of fire and provide safe means of escape for occupants. Cavity walls are essential for insulation and moisture resistance, but the empty spaces within them can enable flames and smoke to travel undetected, posing a significant fire risk and compromising the building’s fire integrity.
Cavity closers are designed to seal gaps around windows and doors and, when made from fire-resistant materials, can also help slow the spread of flames and smoke within cavity walls. Depending on the building type, height and intended use, fire-rated cavity closers may be required to provide 30 or 60 minutes of fire resistance to comply with Approved Document B. Their use is particularly vital in high-risk structures, such as high-rise buildings, where preventing rapid fire spread is essential for evacuating everyone safely.
Part C: Resistance to Moisture
Part C of the Building Regulations focuses on protecting buildings from moisture ingress while ensuring proper drainage and ventilation. Moisture can enter a building through gaps and openings, particularly around windows and doors, leading to damp problems that can compromise structural integrity and create unhealthy living conditions. Prolonged exposure to dampness can result in mould growth, damage to internal finishes and gradual deterioration of the building’s fabric.
Cavity closers with integral damp-proof membranes (DPMs) or similar moisture-resistant features effectively address these issues. By closing the gaps around window and door reveals, they help to create a well-sealed and properly ventilated building envelope, ensuring compliance with Part C requirements. To maximise their effectiveness, window frames should be set back at least 30 mm into the reveal to minimise exposure to driving rain and further reduce the risk of moisture penetration. To reduce the risk of moisture penetration in Severe exposure areas in Part C windows should be fitted in a check reveal.
Choose Subframes UK for Cavity Closers and Compliance
Subframes UK is the largest trade supplier of welded and mechanically joined cavity closers in the UK, offering tailored solutions to suit the specific requirements of your construction project. Operating from our Midlands-based factory, we manufacture both fire-rated and non-fire-rated cavity closers, suitable for a wide range of commercial and domestic builds.
Each cavity closer is manufactured with precision and engineered to deliver exceptional thermal efficiency, fire resistance and moisture protection. We work exclusively with the most reputable brands in the industry, ensuring our cavity closers meet the highest standards of safety, quality and performance. For quotations, product information or technical support, please contact us today.
