Author Topic: Loss of secondary means of escape  (Read 29174 times)

Offline shaunmckeever

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Loss of secondary means of escape
« on: April 01, 2006, 12:03:51 AM »
I have a building I am advising on. The building is listed. It has a single staircase and has 8 floors including ground and basement. Access to spaces off of the staircase is via single doors at each level. The doors are part of the listed status and do not provide any comparison to modern day fire doors. They are not fitted with intumescent strips or cold smoke seals. The building is multi-occupancy with the lower floors  (B, G, 1 & 2) occupied by a single shop unit. The upper floors are multi-tenanted offices.  The detection system will be an L1 system (not installed yet but soon will be).  

My problem is until recently a secondary means of escape was available via a roof and through a neighbouring property however this route is no longer available. There is no other secondary route available. Installing two door separation to the single staircase makes the building non viable due to the loss of lettable space.

What are my options?

I have considered pressurisation of the single staircase and upgrading of the doors but these create their own problems.

Offline kurnal

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Loss of secondary means of escape
« Reply #1 on: April 01, 2006, 08:20:19 AM »
Sounds like a small unit but even so its pushing the boundaries too far.
Does the single stair continue to basement? Does it discharge to a final exit?
The office accommodation sounds untenable to me, and even for the shop to continue the doors need upgrading - would they meet the English Heritage spec for upgrade ( 35mmstiles, 6mm panels?)
A combination of sprinklers, ventilation to the stair, full AFD and upgrade all doors  may be a solution but needs agreeing with local friendly fire safety Officer. If he sees it as it is it is more than likely to result in a prohibition.

There a lot of buildings like this about, the brigades tend to not go looking for them but will act when they do come across them.

Chris Houston

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Loss of secondary means of escape
« Reply #2 on: April 01, 2006, 10:10:37 AM »
Does the building have timber floors and stairs?

Offline Paul

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Loss of secondary means of escape
« Reply #3 on: April 01, 2006, 10:14:09 AM »
I would look at why the original secondary MOE is no longer available.  Check to see if there is a ' deed of easement'.  If there is then this must be opoened up again.  Even if it enters another property.

Offline Ashley Wood

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Loss of secondary means of escape
« Reply #4 on: April 01, 2006, 10:32:29 AM »
I worked on a project similar to this scenario about 12 months ago. The only way we could get acceptance was to have installed a high pressure water mist system. This was done and the building was accepted. Originally a sprinkler system was asked for but it would have been an absolute nightmare to have installed so the high pressure water mist system was proposed as the maximum pipe size was only 18mm! I can point you in the right direction for these systems if you wish? Just e-mail me?

Chris Houston

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Loss of secondary means of escape
« Reply #5 on: April 01, 2006, 11:23:14 AM »
Quote from: Ashley Wood
I worked on a project similar to this scenario about 12 months ago. The only way we could get acceptance was to have installed a high pressure water mist system. This was done and the building was accepted. Originally a sprinkler system was asked for but it would have been an absolute nightmare to have installed so the high pressure water mist system was proposed as the maximum pipe size was only 18mm! I can point you in the right direction for these systems if you wish? Just e-mail me?
Ashley,

Would you be willing to give us some detail about the specification of a water mist system for such purposes.  i.e. what standards was it installed to, what areas were protected, what circumstances lead to the system activating, what duration is the mist supplied for, what is the maximum size of fire it can deal with?  Was it easy to get FRS and insurer approval for the system?  Are you as confidennt in the systems robustness as an approved sprinkler system?

Offline shaunmckeever

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Loss of secondary means of escape
« Reply #6 on: April 01, 2006, 03:15:24 PM »
Thanks for the responses so far.

Kurnal, the stairs do not continue to basement but discharge direct to open air. I'm not sure if the doors meet English Heritage spec for upgrade, this is one of the problems I was referring to about upgrading of the doors. It is certainly one of the options I am looking at.
Chris, the stairs and floors are of timber construction.
PSmith, the issue of secondary means of escape has been totally exhausted and is just not an option although it is the one that would be most satisfactory.
Ashley I am interested in your proposal for a water mist system but I think Chris raises a lot of valid questions. I would be interested to hear a bit more.

Regards, Shaun

Offline Martin Burford

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Loss of secondary means of escape
« Reply #7 on: April 01, 2006, 06:10:43 PM »
Shaun

A good interesting project no doubt.

I would make the following observations:

WITHOUT INTIMATE DETAILS OF THIS BUILDING, I ONLY MAKE COMMENTS OF A GENERAL NATURE.

Special problems of historic buildings.
Firstly ..the construction and form of historic buildings frequently incorporate features which may assist in the rapid development and spread of fire.  For example, exposed timber floors, walls lined internally with combustible materials, continuous voids behind panelling and undivided roof spaces.. to name but a few.

Secondly... the impact the measures need to provide satisfactory means of escape, have on the sensitive architecture and historic settings.

From your brief narrative, it is clear the means of escape may be unsatisfactory, and from the existing use as shop and office accommodation it would appear that there is the potential for significant numbers resorting to the premises.

Your first step should be to consult with BS 5588 Parts 3,4 & 11 and take your guidance from these documents.  I would not consider the use of water protection in any form and I suspect neither would English Heritage.  I also confirm that pressureisation of the staircase may be your answer along with addition protection to the doors leading off such a staircase... however it would seem to me that as a minimum 2 door protection to the single staircase is essential.... Is it not possible to upgrade the doors using Intumestscent treatments... also check out BS 8214......and the relevent TRADA documentation on Fire Resisting Doorsets by Upgrading.  Hope this helps.... but if you need any further assistace contact me via my email address.
Regards

Conqueror.

Offline kurnal

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Loss of secondary means of escape
« Reply #8 on: April 01, 2006, 07:52:59 PM »
Conqueror
What have sprinkler systems done to offend you?
I dont think English Heritage would have a problem with them- especially since the Windsor fire. They have been fitted in much of Chatsworth House with great success.
They make an active contribution to both life safety and heritage by attacking the  fire in its early stages.
Passive measures will do nothing to protect the fabric of the building and a lobby approach will surely detract from its character?

Chris Houston

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Loss of secondary means of escape
« Reply #9 on: April 01, 2006, 08:06:00 PM »
Quote from: Conqueror
I would not consider the use of water protection in any form and I suspect neither would English Heritage.
Can I just say, if you are suggesting that water and historical buildings don't mix, the fire and rescuse services won't hesitate applying a lot of it (indeed a lot more than a sprinkler system will) should a fire occur.  The insignificant amount of damage that a sprinkler system may do is a drop in the ocean compared with the fire damage and the water damage from a fire fighters hose.

Chris Houston

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Loss of secondary means of escape
« Reply #10 on: April 01, 2006, 08:07:33 PM »
I'd also like to add that I was not implying that a water mist system was inferior to the sprinkler system, I was just asking some questions to learn more.

Offline Nearlybaldandgrey

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Loss of secondary means of escape
« Reply #11 on: April 02, 2006, 12:55:40 PM »
Just reading this with interest........

My question is how are the premises remaining in use when there is a single staircase situation and 8 floors?

Surely there is a slight exceeding of travel distances here?

I note there is no AFD, so is there an interim measure in place to give warning in the event of fire until such time the alarm is installed/commissioned?

I have to say, and this is my opinion, that if I was made aware of this premises, I would seriously consider a section 10, or as a minimum, restrictions on the use of most of the upper floors. This decision would be based on the risk to life of persons resorting to the premises, its use, the single direction of travel and distance and lack of fire detection.

Offline ian gough

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Loss of secondary means of escape
« Reply #12 on: April 02, 2006, 09:15:46 PM »
Chris, you are right to be cautious. There is currently no BS or European Standard for water mist systems.

Offline kurnal

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Loss of secondary means of escape
« Reply #13 on: April 02, 2006, 10:59:33 PM »
Hi Ian
you are right about the lack of standards at the moment- though these systems are widely used in ships and there are some very rigorous IMO standards, and many of the tests replicate occupied rooms.

I think if its good enough for a ship where lets face it you are out there miles away from any help and with little chance for escape then it must be worthy of consideration on terra firma. The problem is as always breaking into an existing market with a new approach.  The politics and in my opinion some of the vested interests of the sprinkler industry have  so far held the technology back, though some of the big names are now starting to move things forward. And it can be used on difficult fires - switchrooms, engine rooms etc.
The standards will lag some way behind the market - and therefore it will take some brave decisions to move it forward.
That being said, the rather extreme situation under review may call for the surety of an unlimited water supply if  at all possible.

Offline Ashley Wood

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Loss of secondary means of escape
« Reply #14 on: April 03, 2006, 10:59:38 AM »
Firstly, let me give a little back ground as to the project I was involved in. It may or may not fit this scenario but it is worthy of some debate and consideration.

The project involved a large listed building in the historic heart of Edinburgh. I do not wish to mention the client other than to say it was a major Scottish bank and this was its head quarters building.

The problem was that the building was a rambling building with many floors and mezzanines that had been added over the years, as result the means of escape had become a bit of a shambles. Whilst there were other escape stairs, these were not accessible to a large % of the staff within the building (including the board of directors)! The only escape route for the people within this part of the building was down a single stairs, down four floors (or up if you were in the basement) and out into a large reception lobby. A lot of the office areas off the stairway had no doors let alone fire rated doors! The inspecting authority were rightly concerned by this and insisted that as part of the building refurbishment a solution must be found. They wanted the stair way to be enclosed, but this would have upset the conservationists and the architect. In the end the solution that was agreed was to fit fire doors to all offices and corridors opening onto the escape stairs and to protect the escape stairs with a high pressure water mist system. The system selected was Fogtec but there are others that would have been acceptable for the task. I advised that the system should be controlled by smoke detectors rather than by heat activated glass bulbs, but this was not taken up. There were several reasons why the fire authorities accepted this solution.

1) The ability for the system to remove a large quantity of large smoke particles i. e smoke washing and to keep the escape stairs free of smoke.
2) The rapid temperature reduction that you see when these systems operate.
3) The ability to suppress and control, and in some instances extinguish a fire within the large lobby area.

In general it was seen by the fire service as an escape stair protection solution and to extend survivability to escapees.

From an engineering point of view there were many reasons for this system to be chosen, including;

a) Low water consumption compared to a sprinkler system.
b) Smaller water storage capacity required.
c) Small bore stainless steel pipework.
d) Ease of installation within an architecturally sensitive building.

The final solution was a pump system producing 120 lpm at 100bar pressure, wet pipe, fast acting bulb actuated nozzles and a 1000 ltr break tank toped up from the towns mains via a 45mm feed pipe at 6bar. Each nozzle produced 12 lpm of water mist with droplet sizes of between 60-100 micron, the K-Factor was 1.2

Now, moving onto the questions concerning approvals. There is NO BS for these systems, there is no LPCB approval for these systems. The reason for this is that the LPCB do not have a test written for HPWM systems and the BS do not have any interest! However, there are approvals available but all a risk specific i.e FM, VdS, IMO, Lloyds. Primarily these systems grew up in the shipping and offshore business and as mentioned before, the testing requirements for these applications are very stringent. From these tests organisations such as Factory Mutual (FM) developed there test standards and approvals. For example IMO A800 which covers all accommodation & public areas on board a ship is the basis of the FM light and ordinary hazard approvals.

I have worked with these types of systems now for many years and can say that they are not a 'one size fits all' solution. For example any deep seated fire would not be controlled by a high pressure water mist system in the traditional sense, but install a detection system to activate the system rather than using glass bulbs, and the system works very well indeed. These systems are not new, in there present form they have been available since 1990, but infact were around 100 yrs ago!

The sprinkler companies are concerned that there traditional market may be at threat and as such often mislead people regarding what these systems can and cannot do. However, they have seen the writing on the wall and are them selves now offering HPWM systems. If you were to compare a sprinkler and a HPWM system on price, lets say for a supermarket, sprinklers would be in the region of 25% cheaper. This is due to the fact that HPWM systems use 316 stainless steel!

For cases where it is not practical to install sprinklers due to water supply problems, space restrictions, architectural constraints etc, these systems are worth a look at. A word of caution, and this is where an LPCB accreditation would be useful (but one does not exists), whilst some companies profess to being 'water mist specialists' this is often not the case. This is even the case for the large fire protection companies. My experience is that there are one or two very good small companies out there that specialise in these systems and often do the installation work, etc. for the big boys!