The LWF Blog

Fire Engineering Design and Risk Assessment – Sprinkler Installation Design – Part 32

February 8, 2018 1:24 pm

In LWF’s Fire Engineering blog series for Architects and others in the building design business, we have been looking at sprinkler installations and how to approach them. Part 31 went through the basics of the spacing and location of sprinklers in terms of maximum allowable spacing. In Part 32, the location of sprinklers in terms of placement, height and purpose will be explored.


Sprinklers should be placed where there are no obstructions to interrupt the flow. They should be sited close to the ceiling at the height they would be most effective. BS 9999:2017 covers the inclusion of an atrium in a building and recommends sprinkler heights depending upon the response time of the head, based on the control of a design fire of 2.5MW.


Atriums cause their own challenges as the inclusion of sprinklers at ceiling level would probably involve heights too great for the sprinkler to affect a fire at ground level. With this in mind, sprinklers placed on the edges of adjacent floors should be sited and designed with consideration given to how they will ensure fire does not spread from the atrium to the protected floor.


The use of sprinklers to prolong the ability of glass to withstand heat from a fire has been well documented. Most commonly, such methods are used on the exterior of a building and are known as external drencher systems. However, although it is not covered by relevant codes, there is no reason why this principle could not be extended to include interior windows. Each situation should be considered individually but as a guide, a sprinkler which was placed within 600mm of glazing should provide a good spray distribution over the area.


Various systems have been used for atrium areas designs and are not covered by design codes so far. Each system should be designed to suit the individual circumstances and fire safety aims, while also satisfying the requirements of the relevant authorities.


Where sloping roofs or soffits are in use, hot gases from a fire would collect at the uppermost point. In such circumstances, the sprinklers should be located reasonably close to the ridge where the angle is 1 in 3 or steeper. The positioning of the sprinklers is important as it affects the speed of operation. In order to ensure the fastest possible operation, the sprinkler should be located between 75mm and 150mm below the soffit, so that they are placed where the hottest gases will be.


In part 33 of this series, LWF will continue discussing sprinkler system installations and will talk about suspended ceilings and pipework systems. 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 for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.


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.



Share this post