The LWF Blog
Fire Safety Engineering for Design – Sprinkler Protection – Part 220
February 3, 2025 11:39 amLWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 219, LWF looked at the principles of fire engineering and sprinklers systems. In part 220, we continue to discuss sprinklers and drenchers used for windows and external edifices.
Standards for sprinkler protection of glazing and external walls are more common in the countries most likely to be using said systems. Australia and Hong Kong are two of the countries where the systems are in common use, although the NFPA in the US has produced guidance for outside protection against exposure fires.
In Australia, standard AS2118.2 – Wall wetting sprinklers (drenchers) provides the necessary requirements of fire protection for external walls, windows and doors. It defines systems which operate automatically, comprising either sealed sprinklers or open with water being released via a detection system.
The use of water to provide glazed areas with a period of fire resistance is an accepted method following research from Kim and Lougheed in 1997. Fire Protection of windows using sprinklers (PDF) resulted in the development and widespread use of specific window sprinkler systems. The system provides a fire resistance level of 60 to 120 minutes. While this type of system is highly effective in providing fire separation when used as per the manufacturer’s instructions, there are certain issues which should be taken into account.
A fire starting too close to the protected glazing is likely to result in the glass failing. Mitigation of the issue is possible through the use of a 900 mm high spandrel panel, which will provide a level of protection during the initial growth of the fire and allow the sprinkler to react prior to the glazing reaching a fail temperature.
The glass itself should be heat-strengthened or tempered. It should also be vertically unobstructed, as a horizontal mullion negates the sprinkler’s ability to cover the glass effectively. If a join in the glass is unavoidable, it should be butt-jointed in order for the sprinkler to work effectively.
The final point to be considered is that window sprinkler systems are only viable for use on non-opening windows.
In part 221 of LWF’s series on fire engineering we will discuss the extinguishing mechanism of sprinkler systems, which could be summarised as ‘wetting, cooling and inerting’. 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 since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.
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.