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FIRE SAFETY => Fire Risk Assessments => Topic started by: lyledunn on December 06, 2014, 10:07:06 AM
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we are refurbishing a niteclub. The architect has removed an alternative MOE. There is plenty of exit capacity as one wall has two large glass entrance doors but they could not be regarded as alternatives. If these doors are discounted the travel distance in a single direction is right on the money at 18m before alternative routes become available but that single direction is just to the side of the glass doors. We are talking around 300 people here. The architect is confident about his proposals but even with the exactness of regulatory compliance, I hate the idea of not being able to turn your back on a fire or indeed some other sort of emergency such as a bomb!
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Why are you discounting the two large glass entrance doors?
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Tom asks a good question. We don't discount any exits when assessing travel distances. We even include accommodation routes.
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I think he means you cant count them along with the single exit because of the 45 degree rule.
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Correct Colin
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Not for the first time.
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Can I ask, if we treat all the exits that are next to each other as a single exit (45 degree rule) then how many other exits are there from the premises?
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Can I guess, please can I guess, oh go on let me guess.
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Can I guess what your guess is going to be, Colin? I guess your guess is zero.
My guess is 12 (I'm an optimist, deal with it!).
Let's just see who's closest...
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There are two other exits available from the point of max travel set almost 90 degrees apart. Both are double door sets at around 1000 per leaf. A further exit is being considered. I do not share the architects confidence. If my little city centre restaurant was anything to go by, keeping everyone happy will be difficult. Anyway, both BC and Environmental Health are visiting site this week so hopefully we will avoid unnecessary mistakes before we get too far.
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If I understand the documents correctly there are two issues here.
As far as the travel distance is concerned the 45 degree rule comes into play if there are only two exits or the exits are close to each other. The issue is could a single fire cut off both exits?
The other aspect is the occupancy of the room, in this case if the 45 degree rule applies to two exits these need to be counted as one and the discount applied to the exit with the largest capacity and the normal calculations applied from there.
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Bit puzzled Lyle.. If I read it right from you last post you have 4 exits in total but two may have to be counted as 1 as they are close together. So that's three exits 2m wide ie there is sufficient exit capacity for 720 persons but there are only 300 persons present?
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Kurnal,
If I read it right, there are 4 exits, 2 are close together therefore must be counted as one. Discount the widest exit which needs to be the 2 exits counted as one and you are left with the capacity of the remaining 2 exits.
I make it 2 exits at 2000mm wide 5mm per person equals 400 people per exit or 800 in total, again more than the 300 quoted.
Travel distance wise, more than one direction of escape, medium risk, under ADB 45m to a place of safety.
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sorry guys, it must be difficult to fathom what i am trying to describe without a plan. Consider the diagram in TBB describing the 45degree rule. Now consider a further wall to close off the area in which single direction of travel takes place essentially making a large room. However, there are two large glass doors in this wall which exit directly to outside. Now there is an opening in this wall to one side which is 4m wide. This opening allows access in to a larger area which is still part of the room. There will be at least two alternative exits in this room each circa 2000 wide. So effectively there are 3 exits altogether counting the glass doors. There will be around 300 in this adjoining area resulting in an occupancy of 600. My issue is, how can it be that 300 people are allowed in part of a room which effectively has only one direction of travel until occupants arrive at the 4m opening. i have been restricted to 60 in the past in rooms that have two exits and where travel to the exits is less than 18m but the 45 degree rule could not be met for all.
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Give us a sketch it would be much easier. Example http://i1257.photobucket.com/albums/ii506/twsutton1196/page24.jpg
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I think I almost understand the layout. If I look at the diagram in the TB you have an additional wall running vertically on plan just to the right of the exit at the top of the plan, and this wall has a 4m gap opening into the larger space on the left. Also, if I understand correctly, the two large glass doors are near this 4m gap so cannot be treated as a separate exit route from the space.
Now a room with only one way out is restricted to 60 people of course, but this space might be interpreted as a room in its own right or simply as part of the larger space. If a room in its own right then it should be restricted to 60 (note, a fire engineer might look to increase this figure slightly because of the generous width of the escape route) and if it is not a room in its own right but simply part of the larger space then there need be no localised restriction on numbers.
The site visit should yield enough information to make a judgement on the space. It's not uncommon for layouts to produce areas within larger spaces that can be interpreted in two ways like this. The people making the decision should bear in mind the uses the space might be put to, the maximum expected occupancy of the space, the worst case fire loading (size and location), the ease with which people can get to and pass through the gap, ceiling height (of course), the positions of tables and chairs and other potential obstructions (if present), etc.
I wouldn't be surprised if the judgement came out that it's all part of the larger space and that there is no problem but I have to say that, like you, I'm not too keen on the idea of having 300 people all of whom are reliant on a single escape route. It seems a little vulnerable to me. We all know that fire safety is about having layers of safety, if we lose one element of safety then there should be others to maintain an adequate level of safety. With total reliance on a single escape route there's no resilience, no margin for error.
If they seem to be thinking it's alright and you're not happy, you can throw in a 'what if' scenario. It might be reasonably foreseeable, for example, that someone sets up a display or coat stand or lighting rig near the 4m gap. What if that catches fire? Where does everyone go then?
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Phoenix,
Your interpretation of the room layout is spot on and thank you for your detailed response. Will keep you posted on outcome.
Tom,
Yes, I agree that a sketch is needed and will try that method in future.
Thanks to all.