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Compartmentation Guide
What Are Cavity Barriers? A Practical UK Guide
Cavity barriers are passive fire protection systems used to restrict the hidden spread of fire and smoke through concealed cavities in a building. They can be required at cavity edges, around openings and at defined junctions depending on the construction and applicable guidance.
Use this guide as a practical introduction, then check the relevant tested system and manufacturer documentation before selecting or installing a product.
Use This Guide
Understand the principle first
Use this guide as a practical introduction, then check the relevant tested system and manufacturer documentation before selecting or installing a product.
Cavity Barrier Guide
Quick Guide
Cavity barriers are passive fire protection systems used to restrict the hidden spread of fire and smoke through concealed cavities in a building. They can be required at cavity edges, around openings and at defined junctions depending on the construction and applicable guidance.
Key Points
What You Need to Know
Concealed Cavities
Can provide hidden routes for fire and smoke.
Edges & Openings
Common locations where cavity protection is considered.
Ventilated Façades
May require open-state systems.
System Detail
Cavity width and fixing arrangement matter.
Key Principle
Why Cavities Need Fire Protection
Cavities can provide a concealed route through which fire and smoke may travel beyond the area where a fire starts. Because this spread is hidden, it can undermine compartmentation if cavities are not appropriately divided or closed.
Cavity barriers are one of the measures used to address this risk.
Practical Guidance
Where Are Cavity Barriers Used?
Applications can include external wall cavities, rainscreen façades, roof voids, timber frame construction and other concealed spaces.
The exact locations and performance requirements depend on the building design and the form of construction.
Selection & Application
Open-State and Closed-State Barriers
Closed-state cavity barriers provide a continuous barrier in normal conditions, while open-state systems are designed to retain a ventilation gap before reacting to heat during a fire.
Open-state barriers are often associated with ventilated façade systems, but the product must be suitable for the specific cavity and support conditions.
Important Detail
Selecting a Cavity Barrier
Check the cavity width, substrate, orientation, support detail, ventilation requirements and required fire performance.
Fixing details, maximum gaps and the interaction with insulation or façade components should follow the tested system and manufacturer instructions.
Relevant Products
Explore Related Product Ranges
Use the guide to understand the application, then browse the relevant Fire Protection Direct product categories.
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Frequently Asked Questions
Frequently Asked Questions
Cavity barriers are passive fire protection systems used to restrict fire and smoke movement through concealed cavities.
They can be used at cavity edges, around openings and at relevant junctions within walls, façades, roofs and other concealed spaces.
An open-state barrier maintains a ventilation gap in normal conditions and is designed to close that gap when exposed to fire conditions.
They are related but distinct concepts. Cavity barriers protect concealed cavities, while fire stopping commonly protects joints and service penetrations through fire-resisting construction.
Consider the cavity dimensions, construction, ventilation requirements, required performance and the tested system evidence.
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