The LWF Blog
Fire Safety for Facilities Management Personnel – Structural Fire Protection – Part 156June 27, 2022 11:56 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 155, LWF discussed fire and smoke resistant doors. In part 156, we will continue to look at fire doors.
The guidance on performance for fire-resisting doors given in BS 9999 and outlined in part 155 of this blog series is similar but not identical to the guidance in Approved Document B (ADB). ADB looks to address fire spread as well as means of escape. An example is that a door to a service shaft may require a longer duration of fire resistance for compliance with ADB, such doors need no less than half the fire resistance of the wall into which they are fitted. They do not, however, require resistance to the passage of ‘cold’ smoke.
It should be noted that where two standards differ in requirements, the more onerous requirement should be the one applied.
In the past few decades, the standards and construction of fire resistant doors have improved and so doors fitted into existing buildings some time ago will not meet the current requirements. However, where they were deemed acceptably fire-resisting under previous test standards, they are commonly accepted by the enforcing authorities. This is provided that the doors were fitted into the building when they were of an acceptable standard.
When is a fire resisting door not a fire resisting door? When it is open. A fire door must be closed at the time of a fire. This means that a fire resisting door should be fitted with a working self-closing mechanism or where the door does not form a part of the building’s means of escape or is to a cupboard or service shaft, it may be locked shut.
Rising butt hinges are not usually acceptable as a self-closing device, but ADB does accept them in the case of doors in cavity barriers. The self closing device used must be able to close the door from any angle of opening and overcome the resistance of any latch on the door. A self closing device which has a ‘snap action’ in the final part of door travel can be used to ensure compliance.
A fire resisting door may be held open under normal circumstances if they inhibit the flow of people or goods in a building. The accepted methods of holding such doors open are:
- A fusible link which melts at a pre-determined temperature and causes the door to close (certain conditions apply to their use)
- An electronic automatic door release mechanism that permits the door to close when smoke is detected by the smoke and fire alarm system
In part 157 of this series, LWF will continue to talk about fire resisting doors. 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.