Smoke Barriers

Building Regulations provide guidance on where such barriers should be located within hidden voids in a building and they give examples of deemed-to-satisfy barriers for voids in stud walls or partitions.

If a barrier in a concealed space coincides with a compartment wall or floor it will normally be required to provide the same fire performance as the wall or floor. If the barrier is located between such walls or floors however, the barrier is defined as a ‘cavity barrier’ and as such will normally only be required to provide 30 minutes integrity and 15 minutes insulation. There are also instances where insurance companies insist on 30 minutes insulation.

Factors for consideration when determining the correct specification to ensure a smoke barrier will provide the required fire performance include:

• Size of barrier and location
• Differential movement
• Service penetrations
• Adjoining structures

Chapter 9 of the Fire Protection Handbook provides examples of system specifications for a range of smoke barriers.

Cavity barriers should normally be tested or assessed in accordance with BS 476: Part 22: 1987 and be required to satisfy the performance criteria of integrity and insulation for 30 minutes and 15 minutes respectively when exposed to fire from either side.

It should be noted that in some instances, the integrity and insulation criteria must be such that the performance requirement could be considerably higher than that detailed above. e.g. if the cavity barrier is situated at the top of a compartment wall, then this barrier would be required to provide the same fire
resistance as the main wall.