Cavity Barriers

Cavity barriers are passive fire protection elements that prevent flames and smoke from spreading. They work by sealing off the gaps in a cavity during a fire. The materials used in cavity barriers are sensitive to fire. Therefore, they provide essential protection whilst also helping to minimise air leakage and heat loss between the external cavity and the separating party wall. Barriers are used to close concealed spaces and prevent penetration of smoke or flame to restrict the movement of fire within a building. Cavity walls and ceiling voids would be considered concealed spaces and fitted with cavity barriers during construction.

Open State Cavity Barrier (OSCB) is developed to protect the voids between the outer façade and the inner construction element of the building. The product is designed for use in a ventilated façade and allows for a 25mm-to-50mm linear air gap to ensure air movement and drain any moisture within the facade.

Cavity barriers in England must achieve a minimum of 30min fire integrity and 15-min insulation. (BS 9991 Figure 24 and Table 3 and Approved Document B Volume 2). Both documents also allow cavity barriers to provide only 30 min integrity; clause 19.2 of BS 9991 cites 0.5mm thick steel and 38mm timber as a suitable cavity barrier material for the perimeter of windows. Clients should seek advice from a fire engineer to substantiate before deciding to omit the 15 min fire insulation requirement from a cavity barrier element.

Gunfire’s fire stopping technicians are trained to fit these services.

Gunfire offers the following:

Open state ventilated cavity barriers
Cavity barriers for cladding
Perimeter and fire stop cavity barriers