A compartment wall — if properly built with masonry concrete, and with correctly constructed expansion joints — will perform well in the event of fire. Any penetration seal should remain stable within the wall. In modern construction however, dry lining systems are frequently used. A fire resistant dry lined partition is designed to take account of expansion and movement in a fire. The movement is often up to, and some times exceeds, 100mm in vertical expansion or, in the case of ceiling membrane construction, similarly extremely horizontal movement. Severe bowing of the wall or ceiling or both will frequently occur.
The building services penetrating the partition are invariably fixed rigidly to the underside of a concrete floor and there can be a great deal of differential movement between the partition and the services. If the penetration seal around the services is not designed and installed to cope with this movement, the seal will fail, thus allowing smoke, hot gases and flames to pass though the partition. Not only will smoke and fire pass through any hole left by the failure of the seal, the inner faces of the dry lining structure will also be exposed to the fire. It should be clearly understood that if such failure occurs, allowing heat to penetrate within the cavity of a drywall (or ceiling) construction, premature failure of both the integrity and insulation criteria of the structural system will almost certainly occur, resulting in failure of compartmentation.
Frequently, an aperture is left in a wall at its junction with a floor (ceiling) to allow services to pass through. Any ductwork, pipes or conduits etc supported by hangers fixed to the soffit of the floor will remain in place, despite movement of the wall. Such penetrations should therefore be sealed with a flexible materials and NOT with a rigid material. Once the amount of movement has been established it is possible to design a seal that will provide many years of trouble free service. The use of high movement compounds, slip joints and/or fire resistant fabrics will be required for services such as hot water and steam pipes etc, which can expand significantly in long pipe runs.
It is also essential to check that the materials being used for the penetration seal have been tested in a lightweight partition. Materials tested for use in a brick or block wall are not always suitable for use as seals in dry lining partitions.
