The LWF Blog

Fire Engineering Design and Risk Assessment – Fire Attack Access and Planning – Part 59

September 16, 2019 11:34 am

In LWF’s Fire Engineering blog series for Architects and others involved in building design, we have been discussing those elements of building design which relate to firefighting activities. In part 58, we looked at the objectives of internal access for firefighting purposes and considered how travel distances might be extended with the use of protected corridors to provide access to floor areas. In part 59 we will talk about large single-storey buildings.

Large single-storey buildings differ from buildings with more than one storey in terms of the objectives of internal access. Such buildings are most commonly seen in use as warehousing or food processing plants. Often, large single-storey buildings house a lower number of occupants than a standard occupation.

Potential sources of ignition in large single-storey buildings tend to be limited – electrical systems, forklift trucks or arson being the main issues. It is common that buildings of this type have a sprinkler system installed which operates automatically if a fire is detected.

It is not unusual that large single-storey buildings are subject to a fire-engineered solution rather than following the prescriptive solutions provided in regulation. This would allow for extended travel distances for means of escape purposes and would mean that the floor area would exceed the 50 m travel distance for firefighters into a fire compartment.

In cases where a fire in a large single-storey building is not extinguished in its early stages by a sprinkler system, for example, fire history has shown that the rate of growth of the fire will be very fast and this could mean that by the time the Fire Service are able to arrive at the scene and set-up, the fire would be too well-established for firefighters to enter the building and search for any persons not accounted for.

However, not all fires spread this quickly and there are a few situations where the fire remains local to the area of ignition and the Fire Service are able to enter the building. It is possible that a fire may start in an area isolated from other sources of fuel and it may not be able to spread.

It is possible to designate each fire exit door as a fire attack access point, which would require that access and hardstanding was provided for a pumping appliance within 20 m of every fire attack access door, with a water hydrant provided within 40 m of all doors to be used for fire attack access.

This solution is feasible, but the chances of the fire still being small when the Fire Service arrive is quite low and the likelihood is that even with each fire door being designated a fire attack access point, a fire which is not extinguished in its early stages will result in the total loss of building and contents.

It would seem sensible, therefore, to allocate budget for active fire protection, such as efficient alarm and sprinkler systems, rather than to adopt the multiple fire attack access point strategy.

In part 60 of this series, LWF will look at the fire attack time line. 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 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.

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