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Fire Risk Assessment - Maximum Occupancy v Exit Capacities
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Hacon40581  
#1 Posted : 13 December 2017 11:57:59(UTC)
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Hacon40581

Many Fire and Rescue Service websites detail that when risk assessing the number of people who can use a building  that the lower of either the floor occupancy calculation or the fire exit capacities/travel distance should be used to determine this.

Does anyone know where this information has come from as it isn't it the RRO or guides? This would mean that if a building used as a place of medium assembly had adequate active fire detection, suitable fire compartmentation, a quick evacuation time (for more than the lower figure etc) that it wouldn't be relevant if the number of people in the building exceeded the lower figure.

I would appreciate your thoughts.

Edited by user 13 December 2017 11:59:30(UTC)  | Reason: spelling error
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Lisa Boulton  
#2 Posted : 13 December 2017 17:13:18(UTC)
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Lisa Boulton

Building Regs Approved document B, will give you the floor space factor (FSF) as one method of calculating occupation limits as is calculating the capacity of the means of escape, the lowest figure wins the 'top trumps'.

Its logical to say that if you calculate occupancy using FSF and it states the building can hold 100 people but your means of escape calculation states you can only safely evacuate 80 people then means of escape can't be exceeded and wins, if that makes sense.

Converseley if you have means of escape that allows for safe evacuation of 100 people but the FSF calculation states you can only accommodate 80 people without overcrowding then FSF wins, you can't overcrowd even if your evacuation can safely evacuate more people.

You need to do both calculations to determine what is your safe occupation limits. Lisa

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Hacon40581  
#3 Posted : 13 December 2017 17:26:20(UTC)
Rank: Forum user
Hacon40581

Thank you Lisa, for new builds yes, but the information I have seen leads you to the conclusion it needs to be applied retrospectively too.

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