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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: Messy on January 13, 2016, 08:08:26 PM
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I have a very large but unsprinklered office building with a occupancy of several thousand. The design of the building has created wasteful large staircase landings within protected routes. Until now as you would expect, there has been a zero tolerance regarding combustibles being used or stored in these areas.
The RP now wants to create seated areas to act as meeting spaces on these landings. I suggested metal furniture and a trail set of (hideous & uncomfortable) furniture was supplied on one floor. The trial has gone badly! The RP now wants to have 'warmer' timber furniture and is suggesting researching the use of FR coatings on timber furniture - including glulam type furniture.
So, is there any solid timber furniture suitable for use within a protected route?
Or perhaps can anybody recommend a coating, process or method of treating existing furniture or virgin timber/ply if we go out and get bespoke seating built?
Any suggestions would be gratefully received
Specifying fire resisting materials - as you can see - is not an area I am familiar with!
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Would you allow a vending machine or a photocopier in these staircases?
I would guess that there is more than one staircase? The building has been designed to cater for evacuation of the occupants in the event of discounting a staircase?
The chances of a fire occurring in a staircase is remote (depending on ignition sources and fuel loading).
It doesn't answer your question but is there a need to do anything other than it conforms to current furniture regs?
The problem comes around limiting the amount of furniture and ensuring it doesn't become a permanent workspace. As many places have discovered if you allow the pot plant in the staircase it escalates, its easier to have a zero tolerance. You may have considered this already, apologies if you have.
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Anything comfy will burn. People bring stuff with them - this burns too. People cause fires.
Normal furniture regs reduce the risk but they still present a significant fire load once you get them going. You could go down the route of adopting the same spec they use in airliners but its best just not to do it.
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Messy I know you will have already done this but a risk assessment may be helpful in evaluating the level of risks. If a fire did occur in one of the staircases would it put relevant persons at risk? The evaluation of risk would include number of staircases and their disposition, the number of staff and their total travel distances, the separation of those staircases from the adjoining accommodation, provision of detection, ventilation or suppression systems. The rule about protected routes being sacrasanct is a good, safe fall back to use and absolutely essential in a building with limited staircase capacity but it can be a simplisitic approach- it sounds like your building will probably have a number of staircases. It might be useful to remember that the design codes and building regs allow for many buildings to have accommodation staircases completely open to one or more floors often with a much higher fire loading than an office. Is a bit of furniture in an enclosed staircase that is not critical to means of escape a bigger risk than an open staircase in a retail unit?
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the trouble with a fire in a stairway is that the whole design is based on the assumption that there won't be one.
How does the population of the building know not to use that particular stairway?
Do we wait until they have all moved to it, seen the smoke and turned away - walking into their colleaguse coming towards the stair...
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To some extent I would disagree with Brian, the assumption when working out the occupancy of a building, floor or room is that one of the exits is not available, hence people are going to have to turn round and go another way.
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Hi Brian I am not saying putting furniture in a staircase is a good idea. I am saying the risk needs evaluating to identify the necessary response. Lets face it reception areas, seating areas, displays, cafes, UPSs, file servers are very commonly found in staircases in office buildings. So the risk assessor has to determine what steps are needed. Its easy with illicit storage - zero tolerance - a little harder with seating areas and the like but when you encounter things like file servers and UPS systems its not so easy to have them moved. Sometimes the staircase can be designated an accommodation staircase but as in most cases fire safety design incorporates one storey exit and one staircase being discounted due to the effects of fire then the population has to make decisions as to which route to use.
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I do think Wee B is right - it's a very different matter discounting a staircase because it's been blocked by a fire compared to discounting it because there's a fire in it! In 99% of cases people will not know where the fire is unless they can see it - and they might even choose to use the staircase if all they can see when they open the door is a little smoke. By the time they're in it, it'll be too late.
The need for sterile protected staircases is one of the cornerstones of fire safety design, & when we've gone to the trouble of providing them people really shouldn't be compromising it by installing 'stuff' within them. I know there's always room for risk-based arguments to the contrary, but at the end of the day there are always alternatives to installing vending machines, photocopiers, UPS etc, etc in the one place in a building where you don't want a fire - of any size! Haven't even mentioned the issue of doing it if you have a disabled refuge in the same space...
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Didn't Moreton in Marsh have seating areas in the staircases or where they separated?
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The scene of many an infamous landing party as I recall.
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It doesn't answer your question but is there a need to do anything other than it conforms to current furniture regs?
Just to clarify the situation, in non-domestic premises there is no regulation regarding furniture.
The contract sector, whether it be hotels, offices, schools, hospitals or care homes, the key is ensuring that adequate fire prevention procedures are in place which is an essential safety requirement.
Where fire safety for domestic furniture is defined by legislation, the requirements for the contract sector are, at first sight, more complex.
The Regulatory Reform (Fire Safety) Order requires that there are fire risk assessments in place for all buildings used for non-domestic activities. However, it is not always clear how these relate to furniture. The Fire safety of furniture and furnishings in the contract and non-domestic sectors clearly shows how furniture should be considered in a risk assessment, and how this impacts on different types of usage, together with the obligations of manufacturers, suppliers, specifiers and end-users.
The guide http://www.fira.co.uk/document/fira-contract-flammability-guide-october-2011pdf.pdf
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Thanks to everyone for the useful comments. Working alone, its really useful to seek other views and to make sure I am not being a jobsworth!!!
The building has 10 floors serviced by 10 staircases, all of which are lobbied protected so there has been no discounting of staircases when establishing the maximum safe occupancy. There are no ignition sources in place now or proposed within the staircase enclosure. The building's occupancy is currently 300% more than the figure when the building & original fire safety strategy was designed. However, the occupancy remains just under the safe capacity as determined by a RA, but will reach that maximum figure in the next 36 months.
Two of the ten staircases have been designed with large wasteful landings where these 'drop in' areas are proposed. Neither of these staircases have automatic ventilation and rely on manual intervention by opening a window at the head of the staircase - including one at a very high level a ladder would be necessary!! There is L2 AFD, VESDA and single point, so early detection is likely, but there are no sprinklers.
It is not always possible for evacuees to retrace their steps, as when some enter a staircase, doors on some floors lock closed behind the last staff members as they pass through. During drills, evacuation times to a place of relative safety have been reasonable, but evac times from actuation to outside are fairly long. Being a very large building, there are 40 disable refuges - 10 of them are separated from a staircase where the meeting spaces would be by a single F30. One of the staircases where the furniture is proposed is a firefighting staircase with DRM and firefighting lift.
In a nutshell, this building will be full to the brim very soon and the need to ensure every staircase is available is essential. I really want to accommodate the request for more comfortable furniture, but predict that whilst scores of people are sitting comfortably in meetings, I will be forever uncomfortable with that decision.
Its from this standpoint I am minded to accept only non combustible furniture (stainless or aluminium), or perhaps - if pushed very chunky timber furniture that has been treated. Neither of these options will acceptable to the image conscious occupiers.
I will sleep on it over the weekend before making the final decision
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I fully agree with your concerns Messy. No discounting and a fully occupied building limits your options under risk assessment.
Is there an option to lobby off the proposed seating area from the staircase?
Alternatively as a last resort if you lose the argument could you specify furnishings to HTM standards?
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Thanks again Kurnal, but no - sadly separating the meeting areas from the staircases is not feasible for a variety of design and use reasons.
I hadn't considered the HTM argument to be honest. I had contracts with three health trusts when I was self employed and seen the after effects of a number fires involving HTM compliant furniture . Not wishing to tread on the toes of the 'civilianize enforcement' thread - but when I was a water squirter I also attended NHS and prison fires where perhaps some of the strictest controls of furniture exist, and I still wouldn't want to see this type furniture in any of these staircases.
However, I will carry out some further research along those lines and perhaps compile an options report where a range of choices will be offered, including specialist chairs such as those you mention
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These 'wasteful' landings weren't included for use as refuges/temporary waiting spaces not obstructing escape flow by any chance?
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Bit of advice re: the treatment of timber furniture - if you ask for this (e.g. Class 1 / Class 0, C or B etc) then the tendency will be for suppliers to use an intumescent paint/varnish.
Many of these work fine as far as fire goes, but are relatively soft and aren't at all hard-wearing - might be OK for walls/ceilings that are rarely touched but and are pretty much incompatible with constant physical contact (i.e. being sat on). The impregnation treatments are much better for this type of application, but these have to be applied using an off-site process & compatibility with whatever the final finish will be needs to be checked.
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Fishy - I agree in that I am not happy with treating existing furniture that is bound to be knocked and chipped over the years.
Anthony - No, these landings do not form refuges or any such useful purpose. One staircase has landings of around 20m x 8m - a combined area of 1,600m2 of largely unused space in one staircase alone and in an expensive city centre location. You can see why there's a demand to utilise them for something
I have stuck to my guns and recommended completely non combustible furniture only, supported by a policy of no waste bins and regular housekeeping inspections. I have even hit the interweb and supplied examples of adequate furniture. That's it, job done - other than batting away any resistance that is bound to follow
Many thanks to all for your assistance
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I do know of a similar situation where the answer was in the form of a fire curtain operated by local detection - if the fire is in the furnished area it get's isolated from the stair by the curtain (floor to ceiling type used, more akin to a shutter). Whilst costly the client preferred the cost than more traditional separation.
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The curtain idea would most certainly be feasible in this case. But I have been told in no uncertain terms that this has all got to be done on the hurry up and at as close to nil cost as possible. So a suggestion of installing of 20 x of these rather expensive fire curtains would not be welcomed!!! However, its a useful point to put in as an option at the end of the report in order that funds be made available in future budgets.
Thanks
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Personally I struggle to see what a curtain would achieve. Unlike a permanent structure it would not provide any protection until after a fire was confirmed, detected and the curtain descended. By this time that particular staircase would almost certainly be untenable. Curtains of this size are also very expensive and smoke control and integrity issues arise at the junctions and corners.
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I understand all the concerns expressed but do not think that there is much of a problem here.
You don't treat timber furniture with intumescent paint but you can use timber that can be categorised as being a material of limited combustibility (i.e. a relatively dense hardwood, see ADB or other sources).
Guidance allows a smallish reception to be situated in a staircase when the building has more than one staircase, so provided that the furniture presents no greater fire loading than such a reception area then we remain, in essence, code compliant.
If you wanted to put furniture in two or more of the staircases then I really cannot see the problem in a well managed building. If there is a fire, it will only involve one staircase, it's not going to leap from staircase to staircase. The risk of arson would need to be considered here.
I understand that the building is full to capacity and that all the stairs are required for evacuation. I also understand that if the fire is in one of the staircases then there are a restricted number of escape routes and occupants will take longer to clear the floors and reach a place of 'relative safety'. But this is not important because the fire is enclosed in a staircase and people have at least half an hour to clear the floors in an environment protected from the fire, longer if there are lobbies, longer still if it is a firefighting stair. The floors themselves are places of 'relative safety' if the fire is in a staircase. Confidence in the compartmentation is required for this argument to be valid. Also, of course, the building must not have pressure differential systems installed.
If the staircase has disabled refuges in it then don't use them, use other ones.
If the relevant staircase is a firefighting staircase then this makes little difference.
I am slightly concerned that people can pass through some of the storey exits into the staircases and have the door lock shut behind them. This is not a good idea in any building and has implications for means of escape and for firefighting. I deal with many large multi-tenanted buildings and rarely come up against objections to having all the doors unlock on the alarm. There should be even less reason to object if the building is all occupied by the same organisation. If there are good reasons to have doors remain locked then specific solutions should be put in place to deal with each case.
Care should be taken to ensure that the furniture does not obstruct escape routes and that other more combustible items do not creep in. A daily check should be sufficient.
Yes, the building has to be well managed, yes the locking door issue should be sorted out and yes, we would really prefer it if the furniture didn't catch fire so it should pass the 5852 cigarette and match ignition tests and generally comply with the furniture, etc, regs but otherwise I see no problem.
Finally, you won't be setting a precedent by allowing furniture in the stairs, there are thousands of safe buildings that already have small amounts of controlled fire loading in staircases.
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Guidance allows a smallish reception to be situated in a staircase when the building has more than one staircase, so provided that the furniture presents no greater fire loading than such a reception area then we remain, in essence, code compliant.
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Finally, you won't be setting a precedent by allowing furniture in the stairs, there are thousands of safe buildings that already have small amounts of controlled fire loading in staircases.
Phoenix
Thank you for your post as its this type of scrutiny I was after to check I hadn't missed anything and that I wasn't being OTT. In fact I like your 'make it happen' approach as this is how I try to operate, which is why I am struggling here as I simply cannot give a green light to this proposal.
With reference to the doors locking behind evacuees, the RP does have systems in place which make this necessary security measure suitable from a MOE perspective
It is the aggregate staircase fire loadings + the high occupancy which I am concerned about. I am not content with proposing strategy which permits significant amounts of combustibles in staircases and accepts the possibility (however low) of thousands of people queuing up to 30 minutes in a protected routes where one staircase is impassable.
The RP had placed 4 x sofas on a landing before I discovered it with a plan for 2 more. The proposal was this would be repeated on all floors. This would have meant this particular staircase would have had 54 x sofas and some tables in it!!!! Perhaps more fire loading than an average DFS furniture shop and a little more than a desk, a couple of sofas and a PC that any reception may involve. The second staircase landings are somewhat smaller, but would still have had 36 more sofas spread across the 10 floors.
So all I am saying is lets have these spaces, but use non combustible furniture.
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I understand all the concerns expressed but do not think that there is much of a problem here.
You don't treat timber furniture with intumescent paint but you can use timber that can be categorised as being a material of limited combustibility (i.e. a relatively dense hardwood, see ADB or other sources).
Guidance allows a smallish reception to be situated in a staircase when the building has more than one staircase, so provided that the furniture presents no greater fire loading than such a reception area then we remain, in essence, code compliant.
If you wanted to put furniture in two or more of the staircases then I really cannot see the problem in a well managed building. If there is a fire, it will only involve one staircase, it's not going to leap from staircase to staircase. The risk of arson would need to be considered here.
I understand that the building is full to capacity and that all the stairs are required for evacuation. I also understand that if the fire is in one of the staircases then there are a restricted number of escape routes and occupants will take longer to clear the floors and reach a place of 'relative safety'. But this is not important because the fire is enclosed in a staircase and people have at least half an hour to clear the floors in an environment protected from the fire, longer if there are lobbies, longer still if it is a firefighting stair. The floors themselves are places of 'relative safety' if the fire is in a staircase. Confidence in the compartmentation is required for this argument to be valid. Also, of course, the building must not have pressure differential systems installed.
If the staircase has disabled refuges in it then don't use them, use other ones.
If the relevant staircase is a firefighting staircase then this makes little difference.
I am slightly concerned that people can pass through some of the storey exits into the staircases and have the door lock shut behind them. This is not a good idea in any building and has implications for means of escape and for firefighting. I deal with many large multi-tenanted buildings and rarely come up against objections to having all the doors unlock on the alarm. There should be even less reason to object if the building is all occupied by the same organisation. If there are good reasons to have doors remain locked then specific solutions should be put in place to deal with each case.
Care should be taken to ensure that the furniture does not obstruct escape routes and that other more combustible items do not creep in. A daily check should be sufficient.
Yes, the building has to be well managed, yes the locking door issue should be sorted out and yes, we would really prefer it if the furniture didn't catch fire so it should pass the 5852 cigarette and match ignition tests and generally comply with the furniture, etc, regs but otherwise I see no problem.
Finally, you won't be setting a precedent by allowing furniture in the stairs, there are thousands of safe buildings that already have small amounts of controlled fire loading in staircases.
The key issue, though, is you're assuming that everyone who needs to escape knows there's a fire in that staircase & no-one uses it. I'm personally not convinced that's a safe assumption. You would potentially be compromising the Basis of Design for the entire premises. We don't design buildings with too many protected staircases - we put in just enough and no more.
Also:
There is no such thing as a timber that is a "material of limited combustibility" and there is no treatment that would allow any timber to meet that performance (as defined in the guidance to the Building Reg's). Density is not necessarily a good indicator of reaction-to-fire performance (for example, Ash is relatively dense but it has that name for a reason)!
You should never equate fire resistance ratings with the length of time you'll be 'safe' from a fire - they are simply a means of ranking fire resistance performance and the length of time something may stand up to a 'real' fire will in all likelihood be completely different (longer or shorter).
If you compromised a fire-fighting staircase / lobby by placing furniture in it then (if you're in England & Wales) you might arguably be committing an offence under Regulation 38 (Maintenance of measures provided for protection of fire-fighters).
At the end of the day, though it might be convenient it is rarely (if ever) necessary to install combustible items in staircases - so the first port-of-call for any risk assessment - eliminate the hazard - ought to be applied in most cases.
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Yes, ok about the timber, Fishy. But that's not the issue here. You state that the key issue is that everyone has to know there is a fire in the staircase. I don't think anyone would have to be in a staircase for long, if at all, to detect that there is a fire, or at least smoke, in it. In which case they can leave the staircase and use another route. This is the principle that is accepted when we allow reception desks in staircases so it cannot be argued that this is an unacceptable principle. This is why I was concerned about the locking doors.
I find it hard to imagine the RP being prosecuted for contravening Article 38 but you're right that this should be considered. However, I do know of a few new fire engineered buildings where firefighting access to upper floors is via routes that contain some fire loadings. The thinking is that if the fire is not in the firefighting access route then the fire loading makes no difference and if the fire is in the firefighting access route then they can either use one of the alternative routes (if distances permit) or simply tackle the fire directly from within the space. I agree that there could be firefighting issues if the nearest alternative firefighting staircase is far removed from the one with the fire and if the fire is higher than about the 6th floor.
Messy, if the sofas are reasonably spread out it could be reasonable to suppose that a fire would be slow to spread from one landing to the next if, indeed, this is even deemed possible. When we sprinkler a building we assume that, in the event of a fire, only a relatively small proportion of the many hundreds of sprinkler heads in the building actuate because the sprinklers control the size of the fire. Similarly here, if you are satisfied that the space separation between sofas on adjacent landings is sufficient to control fire spread from one level to the next then we don't have to be concerned about the sheer number of sofas in the staircase, we only have to be concerned about the number that could be expected to be involved in the largest reasonably foreseeable fire. The desire to restrict fire spread is why, if sofas were allowed, there would have to be regular checks, at least daily, to ensure that other combustibles are not permitted (maybe one or two magazines).
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Yes, ok about the timber, Fishy. But that's not the issue here. You state that the key issue is that everyone has to know there is a fire in the staircase. I don't think anyone would have to be in a staircase for long, if at all, to detect that there is a fire, or at least smoke, in it. In which case they can leave the staircase and use another route. This is the principle that is accepted when we allow reception desks in staircases so it cannot be argued that this is an unacceptable principle. This is why I was concerned about the locking doors.
I find it hard to imagine the RP being prosecuted for contravening Article 38 but you're right that this should be considered. However, I do know of a few new fire engineered buildings where firefighting access to upper floors is via routes that contain some fire loadings. The thinking is that if the fire is not in the firefighting access route then the fire loading makes no difference and if the fire is in the firefighting access route then they can either use one of the alternative routes (if distances permit) or simply tackle the fire directly from within the space. I agree that there could be firefighting issues if the nearest alternative firefighting staircase is far removed from the one with the fire and if the fire is higher than about the 6th floor.
Messy, if the sofas are reasonably spread out it could be reasonable to suppose that a fire would be slow to spread from one landing to the next if, indeed, this is even deemed possible. When we sprinkler a building we assume that, in the event of a fire, only a relatively small proportion of the many hundreds of sprinkler heads in the building actuate because the sprinklers control the size of the fire. Similarly here, if you are satisfied that the space separation between sofas on adjacent landings is sufficient to control fire spread from one level to the next then we don't have to be concerned about the sheer number of sofas in the staircase, we only have to be concerned about the number that could be expected to be involved in the largest reasonably foreseeable fire. The desire to restrict fire spread is why, if sofas were allowed, there would have to be regular checks, at least daily, to ensure that other combustibles are not permitted (maybe one or two magazines).
I have to say we'll have to agree to disagree... how do they get out of the staircase when everyone else is trying to get in (which is what all the fire exit signs are telling them to do)?
As I said, when we design buildings we spend good money (sometimes a lot of money) constructing these routes to be protected and sterile, as recommended in the various standards, so why compromise them unless it's absolutely necessary (which it rarely - if ever -is)? You can always come up with scenarios whereby if everything goes right & a fire event is perfectly managed then some of this stuff might not be absolutely necessary, but the standards don't assume everything goes right - they assume it doesn't & build in a certain amount of resilience to cope with the unforeseen. I'm not normally brave enough to assume that in the rare event of a large fire everything will be perfectly managed....
...and so far as the combustible stuff in the fire-fighting routes is concerned... again it relies upon everything going perfectly & the Brigade knowing exactly where the fire is before they commit. I wouldn't have written that fire strategy with a clear conscience!
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We don't design buildings with too many protected staircases - we put in just enough and no more.
Is this really true? When determining the occupancy of a building, one method is to discount a staircase. So in effect, that becomes a 'spare' staircase which is surplus to requirements in terms of a MOE strategy. It could be lost due to fire and there would be sufficient capacity in the remaining stairs
The building I have been referring has a lobbied staircase situation on all cores. Therefore no staircase has been discounted when the building's capacity has been determined and it will be running at max capacity soon. Therefore all staircases will be needed to satisfactorily evacuate those present - Thus my rationale for maintaining 'sterile' environments in the protected MOEs
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Is the capacity of each staircase limited by the staircase width (ie table 7 ADB calcs) or by the doors? Table 7 is based on a 2.5 minute evavuation time, in some non combustible buildings it might be appropriate to consider 3 minutes as a reasonable time?
If all staircases are used to full capacity without discounting, then clearly if a staircase is unavailable queues are inevitably going to arise at storey exits leading to other staircases, starting on the fire floors and those above. Simple arithmetic, together with a judgement on the quality of fire doors and screens will indicate if this is likely to be a problem during the evacuation phase. I guess that with 10 staircases and reasonable fire safety management by fire wardens queues may not place persons at risk.
Personlly I never compromise on firefighting shafts. I see the "alternatives" argument presented by Phoenix so often as being justified by fire engineers without a fire fighting background. If it were so simple as maintaining alternative routes all we would need is compartmentation. Trouble is firefighting is a dynamic event and often the fire does not behave as expected, other weaknesses or failings in the building lead to rapid or unexpected fire and smoke spread and this requires often a review of tactics, including evacuation strategies for relevant persons.
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I respect all your views and I agree that fire safety is about providing layers of safety to guard against degradation of safety features. But, without knowing the building involved here, I still consider that there is scope to examine the alteratives without rejecting any approach just because the book says so. I know, you'll jump on that comment and say it's not 'just because the book says so', you've thought this through logically and objectively - but I would disagree because I can still see gaps in the argument for rejecting the furniture without closer analysis.
We cannot closely analyse this matter because we, except messy, haven't inspected the building. In view of the lack of direct information in this case I will agree to disagree.
how do they get out of the staircase when everyone else is trying to get in (which is what all the fire exit signs are telling them to do)?
There is very little probability that the pressure of people thrusting forward out of their safe office environment that contains no threat or signs of fire into a staircase that contains, at least, smoke and possibly other signs of fire will be so great that people will not be able to turn round and tell others not to go that way. Remember, in their safe office environment no is going to be panicing, no one will be highly motivated to evacuate and many will be slow to respond, whereas any person who happens to be in the staircase will be reasonably well motivated to leave the staircase. If this were not the case then how could we accept reception desks in staircases?
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We don't design buildings with too many protected staircases - we put in just enough and no more.
Is this really true? When determining the occupancy of a building, one method is to discount a staircase. So in effect, that becomes a 'spare' staircase which is surplus to requirements in terms of a MOE strategy. It could be lost due to fire and there would be sufficient capacity in the remaining stairs
The building I have been referring has a lobbied staircase situation on all cores. Therefore no staircase has been discounted when the building's capacity has been determined and it will be running at max capacity soon. Therefore all staircases will be needed to satisfactorily evacuate those present - Thus my rationale for maintaining 'sterile' environments in the protected MOEs
I agree with your analysis is correct - but I'd have to say that I don't think 'spare' is the right term - discounting staircases gives you the resilience in your evacuation strategy that I was promoting earlier.
If the staircases in this building are lobbied then that strongly indicates that they were all considered necessary when the building was designed - which (in my view) makes your judgement to recommend they be kept sterile spot on.
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...Personally I never compromise on firefighting shafts. I see the "alternatives" argument presented by Phoenix so often as being justified by fire engineers without a fire fighting background. If it were so simple as maintaining alternative routes all we would need is compartmentation. Trouble is firefighting is a dynamic event and often the fire does not behave as expected, other weaknesses or failings in the building lead to rapid or unexpected fire and smoke spread and this requires often a review of tactics, including evacuation strategies for relevant persons.
Well put. I sometimes have to remind my younger colleagues of the inconvenient truth that fires don't read fire strategies... ;)
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I'd have to say that I don't think 'spare' is the right term - discounting staircases gives you the resilience in your evacuation strategy that I was promoting earlier.
That's one thing I would agree on. No fire safety precautions are ever 'spare'. Worse still, sometimes people use the word 'redundant'. Sometimes fire safety features can be removed or left out and the remaining fire safety features will keep the building safe under normal circumstances. But it is our responsibility to foresee and predict the consequences of those circumstances that are not normal which we know all buildings are subject to at some time during their life.