The LWF Blog

Fire Safety for Facilities Management Personnel – Structural Fire Protection – Part 153

March 31, 2023 9:57 am

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 152, LWF discussed structural fire protection and construction. In part 153, we will continue to look at structural fire protection and how it is utilised.

Some organisations are dependent on certain business functions in order to continue, e.g. data facilities, communications facilities, records and patterns for a manufacturing process. Any business-critical functions should be enclosed in fire-resisting construction to help ensure they are preserved in a fire situation.

A particular threat from fire is when it is allowed to grow and spread in cavities such as roof voids and ceiling voids. Such concealed fire spread may allow a fire to develop to the extent it is life threatening before it is detected and evacuation takes place. It is also a distinct threat to property preservation and may cause problems in access by the Fire Service.

Historically, there have been fires which spread in undivided roof spaces causing significant mortalities. In 1973, a fire at the Summerland leisure complex resulted in 50 deaths when a fire started in the void between an external combustible wall and internal linings.

As a result, in 1976, the buildings regulations in England and Wales introduced the requirement for cavity barriers. The performance requirement reads as follows ‘the building shall be designed and constructed so that the unseen spread of fire and smoke within concealed spaces in its structure and fabric is inhibited’.

Approved Document B suggests that concealed spaces should be sealed and divided by cavity barriers, depending upon occupancy type. A cavity barrier is simply a constructed barrier, which may be used for another purpose, as well as to seal or subdivide a cavity.

Doors may be required to perform a fire safety function as well as their main function. They may need to prevent the spread of fire, prevent the spread of smoke or both.

Doors and door surrounds offering fire resistance from 30 minutes up to 240 minutes are available. A 30 minute fire protection door may be made of timber, a 240 minute fire protection door may be constructed of steel. Most commercial premises are only required to have timber doors installed, unless they are to be placed in a high-hazard area, such as a plant room, or when they are installed in a wall of increased fire resistance. In this case, metal doors and shutters may be necessary to maintain the fire resistance of the wall and compartment in question.

In part 154 of this series, LWF will continue talking about doors and fire safety. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.


Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.

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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