Firewall
This assembly of Multichannel side rails is designed to offer lateral support to the cladding assembly, which provides the firewall performance of insulation integrity and stability for the periods derived from test or assessment. Periods up to 240mins are possible.

Firewall systems rely on the performance of the cladding. As the sheeting rails are relatively thin components they have very little heat sink capacity owing to their low mass. When subjected to a fire resistance test, the sheeting rails are heated very quickly and consequently lose their structural strength.

Sheeting rails whether exposed or concealed do retain sufficient strength to prevent the wall from significant lateral movement even after 240 minutes of exposure to a standard fire resistance test.

Sheeting rails with a minimum thickness of 1.2mm and above may be used for both twin skin cladding and composite panels, providing they are structurally capable of supporting the wall between the column spacings for the normal load case.

To reduce thermally induced stresses caused by expansion of the sheeting rails during the early stages of a fire, slotted holes are provided, in the ends of the horizontal sheeting rails. The rails are shortened in length and low temperature fusible washers are used so that thermally induced movement can occur unrestricted.

The cladding suppliers requirements should always be checked especially where special or unusual detailsare required.


General Notes
1. Firewall rails are 30mm shorter in length than standard rails and supplied with 54mm x 14mm slotted holes to cater for expansion.

2. Although bottom rails must be single spanning to suit fire conditions, standard sleeves may be introduced to provide continuity for structural considerations.

3. At the discretion of the engineer, joints on rails may be staggered to provide uniform distribution of wind loadings to support structures.

4. Eaves Beam E265/200 is the only available section if supporting the weight of the wall and must be fire protected.