Flexible Fire Protection
It is of fundamental importance that cavity barriers and fire stopping systems are able to accommodate deflections to maintain the required level of fire protection over time and in differing conditions, including fire. While this requirement is dealt with in Approved Document B (AD B), it is far from obvious and often overlooked.
Section 9.15 deals with cavity barriers which should be fixed to avoid becoming ineffective due to:
- building movement resulting from subsidence, shrinkage or temperature changes
- collapse in a fire of penetrating services
- failure of fixings during a fire
- failure of the abutting construction in a fire.
Fire stopping is dealt with in Section 8.27 but only at the top of compartment walls, which should be able to accommodate the predicted deflection of the floor above while maintaining integrity in a fire. The extent of potential deflections in fires is recognised in this section: ‘Where compartment walls are located within the middle half of a floor between vertical supports, the predicted deflection may be assumed to be 40mm unless a smaller value can be justified by assessment. Outside this area the limit can be reduced linearly to zero at the supports." In this situation, the floor could deflect upwards or downwards as a result of fire, adding to the requirement for flexibility.
Most fire stopping systems are unable to accommodate deflections of this nature but Lamatherm products are available using a unique, patented process of pre-compression to give an integral resilience capable of handling such movement.
For full details of all Lamatherm cavity barrier, fire stopping and compartment floor upgrade systems, please see Fire Solutions.