The LWF Blog

Passive fire protection for Building Professionals – Part 16

May 7, 2020 10:33 am

In LWFs blog series on passive fire protection for building professionals and contractors and those with an interest in structural fire protection issues, we aim to give an overview of the important role passive protection plays in the overall fire safety provision of a building. In part 15, LWF began to discuss the fire resistance of walls and ceilings. In part 16, we will continue from that point.

Flexible wall construction offers many advantages in terms of cost and adaptability for a building, but requires considerably more thought when it comes to passive fire protection. Simple wooden studs lined with plasterboard were previously thought to be sufficient to offer 30-minute fire resistance, however, in reality, there are few fire tests to back up this theory and the vast majority of testing undertaken may have included infilling cavities with mineral wool or similar materials.

It is also important to ensure the builder is well-informed about framing and jointing systems for flexible wall construction. A lack of information on the standards required to meet fire protection standards can lead to a flexible walling system not being fit for purpose or able to withstand the effects of a fire for 30 minutes.

In order to ensure that a flexible walled construction is able to function as a part of the passive fire protection provision in a building, the materials used should be chosen carefully and the installation completed to a high standard.

The materials used for flexible walling systems must be accredited to the correct British Standard depending on whether they are load-bearing nor not. The differences for testing purposes are detailed in BS 476 part 2022 (

A common mistake made by construction professionals is to be unaware that some products required to seal penetrations and linear gaps (i.e. surrounding doors) are specifically designed and tested as being fire-rated for use in masonry construction, but would be inappropriate and ineffective for use in a flexible wall system.

In summary, the passive fire protection products used in flexible walling systems by installers should be able to afford appropriate levels of fire protection and to offer an adequate level of protection when services are responsibly installed into the substrate.

In part 17 of this series, LWF will look at how the natural path of a fire once ignited will travel and how this should be addressed in terms of passive fire protection and construction. 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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