Open State Barrier COSB 25
COSB 25
An Open State Cavity barrier for use in ventilated facade systems, reacting in the event of fire to help prevent the spread of fire.
PFC Corofil Open State Barriers combine non-combustible high-density stone wool with a high expansion intumescent strip fixed to the outer face. Depending on the product ordered, it will be supplied either yellow polythene shrink wrapped or foil encapsulated.
PFC Corofil Open State Barrier COSB 25 are designed to close off air gaps of 25mm, the COSB 44 product closes off air gaps of 44mm. The intumescent strip will expand on heating to close off the air gap between the barrier and inner surface of the facade.
Galvanised steel brackets are supplied as standard, stainless steel brackets can be ordered separately if required.
The fire resistance performance varies depending on which barrier is required to suit the application and build-up of the substrates. Please refer to the technical data sheet for full details. You can contact our technical team if you need assistance with this product.
PFC Corofil Open State Barrier range is compliant with to current market requirements and has been tested to the general principles of EN1363-1 and in accordance with ASFP Technical Guidance Document 19 (TGD 19).
Where should you use Open State Barrier COSB25?
PFC Corofil Open State Cavity Barriers are designed to reinstate the fire resistance performance of facades which have been designed to maintain a continuous air flow around the building and must accommodate a continuous air gap at the cavity barrier. This allows moisture to dissipate under normal circumstances but reacting in the event of fire to rapidly close off the air gap to help prevent the spread of fire and hot smoke.

Downloadable Sheets
Key points:
- Tested in accordance with ASFP TGD19 and to the general principles of EN1363-1
- Provides up to 180 minutes fire integrity performance
- Provides up to 120 minutes insulation
- Suitable for cavities up to 450mm
- Air gap of 25mm
- Third party certified
Intended Use:
PFC Corofil Open State Barriers are designed to reinstate the horizontal fire resistance performance of facades which have been designed to maintain a continuous air flow around the building and must accommodate a continuous air gap at the cavity barrier, allowing moisture to dissipate under normal circumstances, but reacting in the event of fire to rapidly close off the air gap to help prevent the spread of fire and hot smoke.