Cavity barriers must be installed to the tested configuration for the specific product, substrate and cavity width, with fixings, compression levels and orientation matching the test evidence. Incorrect installation can invalidate that evidence and compromise fire performance.
Approved Document B sets out where barriers must be positioned: at compartment floor lines, compartment wall junctions, and the edges of cavities around openings (Volume 2, Section 9, Clauses 9.2 and 9.3 for non-dwellings; Volume 1, Section 9, Clauses 9.10 and 9.11 for dwellings).
In ventilated façade systems, open state barriers such as the VFB 60/60, VFB 120/120 and VFB Plus must maintain the required air gap while still achieving a reliable fire seal when activated. Over-compression is one of the most common installation errors, and it can compromise both airflow and fire performance.
For product-specific fixing schedules and tested configurations, visit the Tenmat Technical Hub.