The LWF Blog

Fire Safety for Healthcare Premises – Cavity Barriers – Part 42

October 4, 2018 12:17 pm

In LWF’s blog series for healthcare professionals, the aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 41 of this series, we looked at the use of ventilation systems in healthcare venues and how this differs in a fire situation to most other types of building. In part 42, we will discuss cavity barriers and fire safety.


Fire and smoke can spread without interruption through concealed spaces or cavities in the construction of a building. Fire can travel to areas far remote from the seat of fire origin through concealed spaces, with the potential to cause a site-wide fire incident and so it is essential that fire-resistant barriers are put in place to restrict the size of any concealed spaces and a fire’s ability to spread through the space.


In healthcare venues, the requirements for subdivision due to hazard protection, sub-compartmentation and compartmentation are such that often additional subdivision of ceiling voids for cavity barriers is not necessary. There are exceptions, however, and one is where sub-compartment walls and walls to fire hazard rooms are constructed with 30-minute fire-resisting ceilings.


Regardless of the requirements for subdivision, it is a necessary requirement to prevent the interconnection of horizontal and vertical cavities.


HTM 05-02: Firecode – Appendix E: Construction and fixing of cavity barriers (PDF) provides guidance on the construction and fixing of cavity barriers in healthcare venues and should be referred to at the building design stage.


30-minute fire-resisting barriers should be installed to provide a subdivision of concealed roof or ceiling voids. The result should be that an uninterrupted roof or ceiling void should not exceed 20 m. Where it is possible to do so, cavity barriers should be positioned to coincide with fire-resisting walls, in order to reinforce compartment boundaries. One exception to this is the ceiling void above operating departments.


30-minute fire-resisting cavity barriers should also be provided to prevent the interconnection of vertical and horizontal cavities, at each intersection of fire-resisting construction and elements containing a concealed space and within the void behind the external face of rain-screen cladding, at every floor level and on the line of compartment walls which abut the external wall.


In part 43 of this series, LWF will continue to discuss the use of cavity barriers in healthcare venues, before beginning to look at the use of sprinkler systems. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.


Lawrence Webster Forrest has been working with their clients for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.


While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.


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