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Passive Fire Protection for Building Professionals – Part 17

May 14, 2020 8:38 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 16, LWF discussed the fire resistance of walls and ceilings. In part 17, we will talk about the natural path of a fire once it is ignited, how it travels and how it can be addressed in terms of fire protection and construction.

It’s a reasonably well-known fact that fire in a building will attempt to spread and grow upwards through the building, the reason for this is that heat naturally rises.  When considering the protection of a building from fire, it is therefore important that the pathway between floors is appropriately protected.

In substantially-built brick buildings, the solution may involve the construction of concrete floors. In a more modern building, fire-resistance may be gained through the fitting of a fire-rated ceiling.

When considering fire protection in a historic building, a fire-rated ceiling may also be the better solution, as traditional lathe and plaster offers little protection from the effects of a fire. Such solutions might involve the fitting of an additional fire-rated layer below the historic construction which can offer significant benefits in preventing the spread of fire and protecting the fabric of the building, as well as achieving life safety aims.

Some manufacturers of intumescent paints may claim that their products offer an additional fire rating to a lathe and plaster ceiling. However, without knowledge of the individual ceiling and its associated provenance and condition, little reliance may be placed in the capacity of such products to actually improve the fire resilience of a lathe and plaster ceiling.

In a similar way to the construction of fire-safe walls, it would not be an adequate solution to simply overboard and then plaster with a fire-rated plasterboard. Without test data relating to the use of such materials along with specifics such as the size of the joists and the thickness or density of the substrate to which the plasterboard would be attached, it is not possible to declare such an installation to have a suitable level of fire protection.

A fire-rated ceiling is most commonly fitted as a system of framed tiles and as such, is a system of parts capable of working together.

In part 18 of this series, LWF will continue to look at the construction of fire-rated ceilings to avoid the spread of fire in a building. 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 management 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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