The LWF Blog

Fire Engineering for Healthcare Premises – Fire Resistance – Part 44

July 19, 2021 11:58 am

In LWF’s blog series for healthcare professionals, our aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 43 of Fire Engineering for Healthcare Premises, LWF discussed fire resistance and fire severity, the calculations and variables. In part 44, we look at fire resistance in terms of stability, integrity and insulation.

The term ‘fire resistance’ can have more than one meaning. It can refer to the construction materials and coatings used on passive fire protection materials, which enable a building to resist the effects of a fire. It can also be used to indicate a period of time for which an element of construction, e.g. a floor, column, door, wall, might survive in a standard fire test in the criteria for which it is tested.

The testing criteria are as follows:

Stability (how long it will avoid structural collapse or unacceptable deformation),

Integrity (the period before it shows cracks or fissures)

Insulation (period for which it will restrict heat radiation to the unexposed face).

The corresponding codes in the Eurocodes are:

  • R for load-bearing function
  • E for integrity
  • I for insulation

The fire resistance time stated is the time until the first failure, although it is likely other failures may occur in succession. It should be borne in mind that a standard fire curve is not a good model for a real fire, which could grow faster and to a higher temperature than the test fire, but have a finite duration due to lack of any one of the elements necessary to sustain a fire – fuel, oxygen and heat.

Another point which must be considered when using fire resistance measures is that localised heating may occur in real fire situations, but not in standard fire tests where furnace temperatures are more consistent. The performance of the overall structure may therefore be quite different from the performance of individual components, due to redistribution of loads.

Fire resistance is therefore a good indicator of a product or element of construction’s protection against fire when compared to another fire resistant product. The fact that a fire door, for example, will be labelled FD 60 cannot be taken to indicate that the door will last as intended for 60 minutes in a real fire situation, as that would depend on the nature and situation of the fire. It can merely be assumed that it has been furnace tested to that time and will be superior in terms of fire protection to an FD 30 door.

In Part 45 of LWF’s blog series, LWF will look at what is meant by the term ‘fire severity’. 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 LWF on freephone 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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