Occupancy numbers

[lyledunn]

I refer to diagram 10 in TBB. Accepting appropriate exit capacity and travel distance requirements, what is the maximum number of people allowed in the smaller of the two areas where travel is in one direction only. Is it restricted to 60?

[nearlythere]

Do you mean "E"?

Are you getting your TB "E" and AD "B" mixed up Lyle. TB "E" is the technical guidance to the fire safety section of Building Regs in NI. The other is England.

[lyledunn]

Hi NT, nope, just pricing a wee job inBristol area. Same diagram in TBE if you would like to comment. Just off now to Europa for a few jars with the folks at TSNI. Merry Christmas to you!

[nearlythere]

Hi NT, nope, just pricing a wee job inBristol area. Same diagram in TBE if you would like to comment. Just off now to Europa for a few jars with the folks at TSNI. Merry Christmas to you!

Have a safe one and watch you dont bump in to you know who. Although he is probably sitting with his feet up in his little shack in the Bahamas.

[Phoenix]

I don't have TBB but I've looked at TBE and I think you're talking about Diagram 2.4 or 2.5 in that document.  Each diagram has an area such as you describe.

Both the areas are essentially three sided spaces and are much different to rooms that only have a single exit (where 60 would be the normal limit). 

Diagram 2.5 specifically states that there is less than 45 degrees between the two widest separated routes but Diagram 2.4 makes no such stipulation.  If you were to put a wall along the unenclosed side of the small space in Diagram 2.4 and to leave a single width doorway at each end of it so that the two doors were as far from each other as possible then you would have a room with two exits and if these exits are more than 45 degrees apart then no one would bat an eyelid if you put 100 in the space.  If you then remove the new wall you will only be making the space safer.

What I'm saying is that if the space is wide with a wide opening to the adjoining space then it may not be necessary to limit the number in the space to any specific number (60 or whatever) but if the space is narrow with a narrow opening to the adjoining space then it may be wise to limit the number in the space to 60.

 

[lyledunn]

Phoenix,
Thanks for the gentle correction, I did of course mean ADB.
You got my query spot on! We intend to make a raised area in this three-sided enclosure with access via three steps in the centre. Railings will then be erected along the open edge and thus the space is effectively enclosed, at least with respect to access. I could get 150 on this raised area all of whom could reach the steps within 18m where the alternative exits in the other part of the room become available. As you say, it might be wise to limit numbers but I could not find anything prescriptive that requires me to do so.

[Phoenix]

Hmm, you get some problematic spaces over there.  If the space is enclosed apart from a single relatively narrow exit route down a few steps then normally we would look to limit the area to 60.  There may be compensatory features that allow some flexibility in that limit such as a high ceiling of low fire load located away from the exit.