We are looking into the maximum number of people we can have in a room with only one exit. Looking at 3.20 we could have 220 people with an exit 1050mm wide.

Is this correct or have I misunderstood the table in 3.20?

Kind regards,

David

David check out 3.8 Number of occupants and exits in AD B (fire safety) and it only allow 60 persons for one exit, although the door will pass 220 persons.

Hello David

It is true that Table 4 at 3.20 of The Building Regulations 2010 Fire Safety Approved Document B states the maximum number of persons who can be accommodated by a final exit door of 1050mm width is 220.

However, what if this exit is blocked by fire? At 3.21, 'Calculating exit capacity', the regulations note that 'if a storey or room has two or more exits, it has to be assumed that a fire might prevent the occupants from using one of them'.

This is true of a room with only one exit. If this one and only exit is blocked by fire, what are your contingency plans? Furthermore, even if the exit is not blocked, to assume the maximum number could be safely accommodated is taking a huge risk; depending on the nature of the fire, a panic situation could develop, with a mad rush of 220 people to the door and the possibility of some being crushed.

Have you thought about creating an additional fire exit via a window?

Kind regards

Sally

David you need to calculate the occupancy of the room and if it is less than 60 person one door will suffice (750 mm) and it can be inward opening.

If the occupancy is more than 60 but less than 600 then you need two doors. The largest one has to be discounted so if the smallest door is 1050 mm it will cater for 220 persons.

If you use double doors (1500 mm) then you could increase the occupancy to another 150 persons and you must also consider the 45 degree rule as well.

After that its more doors.

Maths DOH. 1500-1050 = 450 mm Therefore 5 mm / extra person 450/5 = 90 not 150 like I said above.

Hi Tom and Sally

Thank you for your response. Unfortunately, the room is partly below ground, due to the slope of the ground surrounding the building. So adding another exit is not easy. However, we are considering if we can i the longer term.

David