The LWF Blog

Facilities Management & Fire Safety – Fire Safety Engineering & the Prescriptive Approach – Part 4

November 8, 2018 11:07 am

LWF’s blog series for those who work in Facilities Management or who have an interest in or responsibility for fire safety has been looking at the ideas behind fire safety engineering. In part 3, we looked at how the prescriptive approach was the one demanded by insurers until relatively recently when a more flexible approach was approved. In part 4, we will look at what is good about the prescriptive approach, as an alternative to fire engineered solutions.


While prescriptive methods of fire safety are used less frequently than in the past, in favour of an individually designed fire safety engineered solution, prescriptive approaches can provide a successful approach and in some circumstances, may be the best approach to a project.


The rules of prescriptive fire safety are straightforward and allow a consistent approach.  It requires less complex understanding and assessment by enforcing authorities and therefore can often make for an easier process for the design team. The traditional way offers less risk in terms of liability and in terms of the potential for harm to any building occupants. This is not to say that prescriptive solutions are safer in and of themselves – a well-designed fire engineered solution can be safer, simply that a tried and tested method involves less risk, or at least, less risk-assessment.


It also follows, therefore, that a fire officer or insurance surveyor who has limited training in technical issues and no engineering qualification could more easily understand a prescriptive solution than a fire safety engineered one.

Many guides are based solely on prescriptive solutions and this is largely because the individual elements can be considered in isolation from each other with only minimal crossover between areas. For instance, when discussing travel distances to evacuate a building, prescriptive distances are easily quoted and do not have to be related often to other fire safety or fire prevention provision within the building. A fire engineered approach may sweep aside traditional travel distances because other facilities are in place, such as sprinklers or smoke extraction systems. A fire engineered solution should be particular and individual to the project in hand, whereas prescriptive figures can be compared across projects and buildings.


The vast majority of buildings are still designed as per prescriptive codes and most building work in terms of modification of existing buildings also follows those codes. This is not to say that fire engineers may not be involved with projects which are purely prescriptive in nature, they frequently are.


In part 5 of this series, LWF will look at some of the criticism of the prescriptive approach that has been heard in the last twenty or thirty years. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.


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.


Share this post