Cavity Barriers Explained: Types, Placement, and Legal Requirements
If you’ve ever wondered how buildings stop fire from spreading through hidden gaps and spaces, cavity barriers play a big part in that. They're one of the most important fireproof solutions used to slow down flames and smoke, giving people inside the building more time to leave and helping firefighters control the blaze.
So, what exactly is a cavity barrier? Quite simply, it's something placed in the empty spaces (or cavities) between parts of a building’s structure—like between walls or floors—to block fire and smoke. Without it, fire can race through these gaps unnoticed, making it more dangerous.
There are a few types of cavity barriers, each made for different parts of a building. Some common ones are:
1. Foam barriers – These expand when they get hot to block off spaces,
2. Slab or board types – These are thicker and used in larger gaps,
3. Brush or curtain barriers – More flexible and used in building parts that might move slightly.
The placement of these barriers is just as important as the type. They usually go:
- At the edge of a cavity, like where a wall meets the roof,
- Around openings, such as windows and doors,
- Across long spaces to divide them into smaller sections.
The goal is to stop fire and smoke from reaching other parts of the building quickly. If a building has insulating panels or cladding, special care must be taken, because fire can travel through these layers.
Now, on to the rules. In the UK, building regulations (like those in Approved Document B) say that cavity barriers must be used in certain places in most buildings. They also must last for a minimum amount of time when exposed to fire—often 30 or 60 minutes. These rules help keep people safer and make sure that buildings are built with fire protection in mind from the start.
In short, cavity barriers are simple but crucial parts of fire safety in buildings. Making sure they’re the right type, placed in the right spot, and up to legal standards can help save lives. If you’re involved in building work, repairs, or even just curious about how safe your building is, learning about cavity barriers is a smart start.