Protecting an unprotected staircase

[Meerkat]

Hi All

Haven't posted here for some time.  Good to see the old place is still standing!

I have an issue with a client who has a normal risk commercial building, accessed by members of the public, with three floors above the ground, served only by a single unprotected staircase.  Travel distance to a place of safety, from the furthest point on the upper floor is 40m+ and there is no alternative way out.  Because I am a simple Meerkat, I have recommended they re-instate the structural protection to the staircase on each level that was removed when the building was refurbished.  I'm not the first assessor to do so and the previous one was similarly ignored.  I have no idea how they got Building Regs approval, but perhaps I'm just being naive there!

Client now wants to install a fire supression system to "protect" only the escape route - stairs and the area to and from them across the relevant floors.  System has been designed to be "bespoke" and not in accordance with a newly issue BS.  This in itself is not a problem.

My problem arises, becasue there is no fire strategy that explains how installing this system suddenly "protects" the staircase and allows a travel distance in excess of 40m+ to be acceptable.  I have asked to see the relevant calculations / explanation in accordance with BS 9999 but none has been forthcoming, only an assurance that the route will be "protected" by this system and so I need not worry...

Am I missing some obvious point here or am I being fobbed off?  Opinions greatly appreciated!

[kurnal]

This approach is totally flawed but unfortunately those who don't understand fire safety- some architects, some fire officers and some Building Control bodies are being talked into adopting it as a solution in an increasing number of buildings.

The first flaw is that somehow by installing a sprinkler or mist system in the escape routes only this can be operated in the event of a fire and that somehow this will keep people safe from the fire during the evacuation phase. Whether this is a local conventional system (most common) or a pre-action system  (rarer because of water supply requirements) it ignores the risk posed by smoke.

The second flaw is that partial systems, without fire compartmentation, are a nightmare. Most fires will start in occupied areas rather than escape routes which should be sterile. If there are no sprinkler or mist heads in the immediate vicinity of the fire, the fire will grow, the fire and smoke plume will spread until eventually it reaches the heads that are there and as a result, because the fire has grown bigger, more heads will operate. But they will be remote from the fire and so the water spray will be unable to reach and suppress the fire. So the fire will grow, more heads will operate and very quickly outstrip the capacity of the water supply infrastructure causing all to fail. Tenability across the whole building will continue to deteriorate as the fire grows and a small area protected by spray will not help tenability in the escape routes or elsewhere.

For these reasons all international standards would be breached by such a proposal. It sounds like if sprinklers are the chosen solution then an OH system designed and installed with BSEN 12845 is the way to go. The system must cover the entire building.

This idea is not fire engineering it is a panic measure suggested by a buffoon.

[kurnal]

I omitted  to make an important fundamental point in my last posting.

Suppression systems are designed to suppress fires. They will do this provided certain criteria - such as head spacing, fire loading, water supplies - are met. That is their intended role. In suppressing a fire then the fire growth will be limited, with consequent reductions in temperature within the protected area and the volume of smoke produced. As a result tenability will be enhanced. But the design criteria must be met in order that the benefits may be achieved.

However in this case the proposer is assuming that tenability throughout the escape routes will be enhanced by the suppression system even if the fire is not controlled. Somehow that by spraying water or mist into the escape routes, without hitting the fire,  that tenability will be enhanced.

So the suppression system is being used soley to enhance tenability and not to suppress the fire. How does that work? What tenability criteria are being used and how are these justified?   

The fact is the proposal cannot be justified by logic or fact and will not work. It may pull the wool over the eyes of the ignorant or ill trained but practically is a total  nonsense.

Sorry to sit on the fence

[Meerkat]

So you're not keen on it then Kurnal?

Thanks for the frank response.  It's pretty much what I thought.  Unfortunately the system design has proceeded without my involvement and I now find myself as "the bad guy" becasue I'm querying it.  It seems to have had "approval" from BC, though the letter giving this supposed approval is vague in the extreme and recommends "a fire engineer" be involved in justiyfing the system, which seems to me like a nice get out for BC.

Now I am querying the whole basis of the so-called solution, the designers are saying that as it was "bespoke" it's not to the BS but if we want it to be designed to the BS (EN 12485 or BS 8489), it would be much more difficult to do and we're now talking about tanks and pumps and goodness knows what else, none of which there is space for.  Well, yes.  That's why I (and a previous assessor) suggested re-instating the structural protection in the first place!  The suggested system is water mist by the way, which seems like clever technolocy and I admit I have little experience of it personally, but I don't see how it removes smoke from a smoke-logged staircase...

To return to a second to BS 9999.  As I undersatand it, you may reduce the risk profile if you have sprinklers or water mist fitted.  That allows you to use a different figure for the maximum allowable travel distance.  It's not going to allow you to have a travel distance of 45m with only one means of escape, though in any circumstance. The only way to do this is re-instate the structural protection I believe.

I did also do some reading on this and found some articles about use of sprinklers / water mist in domestic situations and whether they could replace structural protection and the consensus seemed to be - not really.  Mainly this seems to be becasue the escape route could become smoke logged before the suppression system activated and then even when it did activate it would not clear the smoke.  

I can see this one is going to be interesting, as the designer continues to insist that the system in some magic way can be considered to "protect" the staircase and so travel distances magically shirink to 18m on each floor into the so-called protected area!  I have pointed out that "protected" in BS 9999 is defined as "with fire resisting structure" but it's falling on deaf ears.  Oh well, I can't say I haven't tried!

[kurnal]

Meerkat said

"I did also do some reading on this and found some articles about use of sprinklers / water mist in domestic situations and whether they could replace structural protection and the consensus seemed to be - not really.  Mainly this seems to be becasue the escape route could become smoke logged before the suppression system activated and then even when it did activate it would not clear the smoke. "

Any trade offs within BS9999 would be for fully compliant suppression systems. The system proposed is not in any way compliant.

You refer to research into domestic scenarios. That's another area of concern, so often now domestic smoke alarms and domestic sprinklers are being used in commercial situations. Why? Because they are cheaper! But both are very different animals designed to meet different risks.

[kurnal]

Hopefully someone else will help you further by chipping in with their four penn'th. All comments welcome. Please don't be put off by my forthright response if you disagree! I might have it wrong- it has been known.

[AnthonyB]

I wonder what the fire service would have to say about this case, whether they would have the wool pulled over their eyes or would echo your understandable concerns.

Whilst reducing the prescriptive nature of our legislation has allowed sensible alternative solutions and freedom in design it does seem that there are many examples these days of the freedom being taken to the extreme where safety is no longer a priority, just getting that approval.

[Messy]

This thread reminds me that about 6/7 years ago, a friend asked me (literally in a pub) whether it would be possible to create a loft extension in their small terraced open plan Victorian cottage in west London. I doubted it would pass and Building regs unless the old hallway was reinstated with fire doors etc. That - I thought - was the end of the matter

Some weeks later I got a e-mail saying he had phoned his local BC office who had put him in touch with a 'fire engineer'. This guy designed and was to install a bespoke water mist system for a around ?5,000 which would 'put the fire out so they could escape down the stairs'. When I asked some questions obviously doubting the claim, he said he wasn't bothered if it would work or not.

He needed a loft extension for his growing family, and even with the cost of the water mist system, extending into the loft remained considerably cheaper than moving locally to a house with the extra space they needed. So installing the water mist was only to achieve planning permission. He said as soon as he had the completion certificate in his hand they would isolate it - probably before the BC Officer was in is car. They would not service or maintain the system and would only reinstate it when they moved (if ever). he was happy that the part 6 AFD system would suffice and wake him & his family in time.

I am not sure how widespread this approach is, but with no duty to maintain any domestic fire safety infrastructure in a domestic setting, it worries me that his house isn't the only one with an ornamental suppression system

[Meerkat]

Thanks all.  Kurnal - I don't disagree with you at all, but being told that I am worrying about nothing, by people who are apparently more experienced (and qualified!) than I am and who are waving a "certificate" from Building Control had made me wonder if I was being too "prescriptive".

Clearly this isn't a domestic system, but the only report I could find on the net which discussed the issue at all was for domestic situations and I thought it interesting.  Thanks Messy for the rather alarming example.  I guess I'm not alone in wondering what goes on in "Building Control Approval" these days!

AnthonyB - the fire authorty in this case have rubber-stamped the letter from a BC consultant which doesn't describe the system properly anyway, but which has the lovely get-out clause that the system must be "justified by a fire engineer" - which IMO it has not been.

My fear is that the client will put this system in regardless and that a fire risk assessment will then be produced (by the designer!), defining the stairscase as "protected" and thus trumping mine, which required structural protection.  My only recourse at this stage seems to be to put my concerns in writing and stand well back

[Phoenix]

My only recourse at this stage seems to be to put my concerns in writing and stand well back.

I would urge you to do this.  Just a quick thought...

I don't think you've said what the building is used for.  There are some very old heritage buildings, like museums, I've looked at where a 40m travel distance down a single unprotected staircase can be justified through compensatory building characteristics and fire safety management procedures.  Most buildings though cannot be considered safe with such a layout.

In all cases a suppression system such as you describe would be a complete and utter waste of time and money.  When you write to them I would suggest that you stress that you are just trying to save them from wasting their money on a system that will not cover their legislative responsibilities and that is very unlikely to be accepted by the enforcers of the RR(FS)O.

On final point, be confident that you are right.  You're not alone.  I am just doing a job in one of the most important buildings in the country and I am advising them to take out a water mist system that some idiot got them to install a few years ago.

[kurnal]

Whilst reducing the prescriptive nature of our legislation has allowed sensible alternative solutions and freedom in design it does seem that there are many examples these days of the freedom being taken to the extreme where safety is no longer a priority, just getting that approval.

Absolutely spot on Anthony.

 

Thanks all.  Kurnal - I don't disagree with you at all, but being told that I am worrying about nothing, by people who are apparently more experienced (and qualified!) than I am and who are waving a "certificate" from Building Control had made me wonder if I was being too "prescriptive".

.......  I guess I'm not alone in wondering what goes on in "Building Control Approval" these days! The fire authorty in this case have rubber-stamped the letter from a BC consultant which doesn't describe the system properly anyway, but which has the lovely get-out clause that the system must be "justified by a fire engineer" - which IMO it has not been.

My fear is that the client will put this system in regardless and that a fire risk assessment will then be produced (by the designer!), defining the stairscase as "protected" and thus trumping mine, which required structural protection.  My only recourse at this stage seems to be to put my concerns in writing and stand well back

At present that's all you can do Meerkat. But it's not good enough is it. You could also send a copy of the proposal to the other fire risk accessors third party certification body if there is one.
But Even in my little bubble I have come across this scenario several times and companies of Approved Inspectors  / Fire Engineers who would approve  such a proposal and would even recommend it to their clients on the basis of precedent elsewhere. What can we do as Consultants? The Government representatives would say there is an appeal / determination procedure but that is no use to us- the procedures are to be used by the proposer / developer. No developer is going to appeal that they have been let off too lightly!

We consultants will be bound by confidentiality clauses and in cases like those described we will voice our opposition, not be appointed and stand by and watch whilst another company, ( I would say the lowest common denominator but at least one company I know of is TPC accredited) is appointed.

 

In all cases a suppression system such as you describe would be a complete and utter waste of time and money.  When you write to them I would suggest that you stress that you are just trying to save them from wasting their money on a system that will not cover their legislative responsibilities and that is very unlikely to be accepted by the enforcers of the RR(FS)O.
On final point, be confident that you are right.  You're not alone.  

Spot on Phoenix. But wouldn't it be nice if someone in Government picked up on this and at least issued a bulletin on the Planning Portal or similar to say hang on folks this misuse of suppression systems, in which the potential benefits of suppression systems are taken into account without actually installing a system that stands any chance of delivering those benefits, is pushing the boundaries much too far.  It would be good if the suppression industry  / BAFSA would make a comment on this.

[Phoenix]

But wouldn't it be nice if someone in Government picked up on this and at least issued a bulletin on the Planning Portal or similar to say hang on folks this misuse of suppression systems, in which the potential benefits of suppression systems are taken into account without actually installing a system that stands any chance of delivering those benefits, is pushing the boundaries much too far.  It would be good if the suppression industry  / BAFSA would make a comment on this.

Yes, indeed.

[Meerkat]

My only recourse at this stage seems to be to put my concerns in writing and stand well back.

I would urge you to do this.  Just a quick thought...

I don't think you've said what the building is used for.  There are some very old heritage buildings, like museums, I've looked at where a 40m travel distance down a single unprotected staircase can be justified through compensatory building characteristics and fire safety management procedures.  Most buildings though cannot be considered safe with such a layout.

I'd rather not go into detail about exactly what or where it is, but it's certainly not in that category.  I have little experience of heritage fire safety and wouldn't attempt to do FRA for such a building at present.

Thanks everyone.  I am most grateful for all the comments

Meerkat