The LWF Blog

Fire Risk Assessment for Healthcare Premises – Managing Fire Safety – Part 119

January 3, 2023 12:33 pm

LWF’s blog series for healthcare professionals aims to give information on best practice of fire safety in hospitals and other healthcare premises. In part 118 of Fire Risk Assessments for Healthcare Premises, LWF talked about choosing fire safe sandwich panels and how to mitigate those when the core is unknown. In part 119, we begin to discuss external envelope protection and how this might impact a healthcare building in close proximity to adjacent buildings.

It is important that fire cannot spread from one building to another situated close by. For this reason, the external walls or roof must be fire-resistant. This provision works to prevent fire from spreading one building to another or from re-entering the same building in a different compartment or area via external fire spread.

The level of importance of fire-resistant external envelope protection for existing buildings is based upon the proximity of adjacent buildings or compartments within the same building. In a completely isolated building, external envelope protection may not be important as fire cannot spread to another building. However, commonly, healthcare buildings are on a site containing various other buildings and are situated in urban areas and so the issue is one many healthcare providers must consider.

In a situation where a roof abuts an external wall, the roof should provide 60 minutes fire resistance for a distance of at least 3 metres from the wall. This can be mitigated by automatic fire suppression in the area below the lower level roof and the 60 minutes fire resistance for 3 metres may be reduced.

Where a compartment or sub-compartment wall meets an external wall, a 1 metre wide storey height strip of external wall with a fire resistance at least equal to the compartment should be provided to prevent fire spread between compartments.

The maximum allowed percentage of unprotected area of an external wall can be determined by reference to Building Research Establishment’s BRE Report 187 ‘External fire spread: building separation and boundary distances or by reference to the unprotected area graph in HTM 05-03 Part J

The unprotected area graph works by comparing the distance from building/site boundary against the percentage of unprotected area allowed. The greater the distance from the building, the larger percentage of unprotected area is allowed. The use of sprinklers throughout the building in question allows the reduction by half of distance to the boundary with a minimum distance of 1 m maintained.

In Part 120 of LWF’s blog series, LWF will begin to discuss smoke control in healthcare buildings. 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 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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