Fire Rated Cavity Closers and Cavity Trays: Protecting Modern UK Buildings from Fire and Moisture
In modern UK construction, fire rated cavity closers and cavity trays are indispensable for ensuring safe, durable and moisture-resistant cavity wall construction. While they serve different purposes, together they form a complete system that protects the structure from fire, heat loss, cold bridging and water penetration — issues that can compromise the longevity and performance of brickwork if not addressed properly.
A fire rated cavity closer is installed around window and door openings to seal the cavity. By doing so, it improves thermal insulation, prevents cold bridging and reduces energy loss around these vulnerable areas. More importantly, its fire-resistant core acts as a barrier against fire traveling through the cavity. Since cavities can act as hidden channels for flames and smoke, fire rated closers slow fire spread for a specified period, typically up to thirty minutes, helping buildings comply with UK fire safety regulations and providing crucial additional time in emergency situations.
Cavity trays, by contrast, are designed to manage moisture at roof abutments, gable ends, window heads and other junctions where water could penetrate the external wall. They function as stepped damp-proof courses that collect rainwater entering the outer leaf and direct it safely to weep vents, preventing moisture from reaching the internal leaf. Pre-formed cavity trays simplify installation and are suitable for both new builds and refurbishment projects, ensuring consistent protection where changes in roof height or building extensions could otherwise leave walls exposed to water ingress, especially when paired with structural components like the Ancon FHR 100/140 head restraint to maintain stability at critical junctions.
In refurbishment projects, cavity trays are often necessary to replace old, damaged or poorly installed systems. They are also essential when raising roof levels or adding insulation to flat roofs, as the original damp-proof course may no longer be effective. Installing a new cavity tray restores the building’s moisture protection, preventing potential damp damage, mould, and costly future repairs.
When used together, fire rated cavity closers and cavity trays provide a complete defence for cavity walls. The closers protect openings against fire and cold bridging, while the trays handle moisture at critical junctions. This combination ensures compliance with building regulations, reduces the risk of damp problems, and delivers a safer, warmer and more reliable building envelope.
Though often overlooked due to their small size, these components play a vital role in the quality and durability of modern cavity wall construction. Proper specification and installation of fire rated cavity closers and cavity trays is essential for builders and contractors committed to delivering long-lasting, high-performance UK homes and commercial properties.…