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1
Owain, I share your view - especially as the occupancy numbers for this particular premises is quite large

Tom, many thanks for that information as it certainly does provide some context/rationale for this MOE layout, especially as this building is indeed rather old. It is obviously the source of my understanding - in 14.44 (b) - that the protected route should lead to the final exit.

I must have been looking out of the window at Moreton when the alternative - 14.44(a) - was discussed. I did a lot of dozing off in those days :)

I will embark on a programme of fire door upgrades to beef up the separation between escape routes that are required

Many thanks for your help
2
The old blue guide for the FPA 1971 stated,

14.44 Ideally stairway enclosures should lead to a final exit. Where there is only one stairway from the upper floors(s) of a building and a final exit cannot be provided from the stairway enclosure , one of the following arrangements should be adopted.

(a) the provision of two exits from the staircase enclosure each giving access to a final exit by way of routes separated from each other by fire resisting construction (see diagram 14), or

(b) the provision of a protected route from the foot of the stairway enclosure leading to a final exit (see diagram 15)


So if the building was constructed last century could this not be the reason.
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It sounds nuts to me to not have a protected final exit route for a 20 storey building.

And what about disabled refuges on the staircase?  Even if there isn't a lift, a person who can manage a couple of flights of stairs to an upper floor slowly, normally, may be unable to do so in an emergency situation.
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I am having a senior moment and questioning something I previously thought was basic stuff

During an evacuation, when a person enters a protected route, my understanding is that under normal circumstances, they should remain in a protected route until they reach a place of safety.

I have come across a case where the strategy is for persons escaping to use a 20 storey protected staircase with lobbies and pressurisation) and then leave that protected space on the ground floor to travel to the final exit through open plan office and other unprotected areas.

It is fair to say, where this happens, there are two unprotected routes to a final exit on the ground floor that are entirely separated, therefore staff will be able to turn their back and make they way along the alternative route. Several hundred persons (staff) will be required to use the routes.

My concern is all about time. When staff enter the staircase on the top (19th) floor, being protected space and pressurised, there is less urgency for them to reach a place of ultimate safety. However, by the time they reach the ground floor and have the choice of two unprotected routes, separated  by a 30 min FD, I am concerned that smoke from a fire on the ground floor may started to enter the escape route

Any comments - as usual - will be gratefully received

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Technical Advice / Re: Heat calculation
« Last post by lyledunn on January 16, 2019, 07:54:59 AM »
Thank you Fishy for your detailed answer. I have noticed recently that determinations reached by fire engineers that are not supported by test procedures relevant to the situation are failing to make passage through BC. Your example perhaps illustrates the reason.
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Technical Advice / Re: Heat calculation
« Last post by Fishy on January 15, 2019, 08:38:40 AM »
I a word, no.

Longer answer... there are techniques available to determine (based upon fire load) whether structural fire protection (which might include plasterboard) is adequate or not (in terms of load-bearing capacity) - normally defined within the relevant structural Eurocode (e.g. EN1993-1-2 - see here: https://eurocodes.jrc.ec.europa.eu/doc/2012_11_WS_fire/presentations/04-ZHAO-EC-FireDesign-WS.pdf ).  This is only, however, relevant to load-bearing capacity (R), not 'E' and 'I'.

The issue with fire separating elements is that their fire resistance is often not entirely controlled by the heat energy input alone - e.g. they can be sensitive to the rate of heat rise.  Their response is often not linear - failure can be sudden and not necessarily predictable (e.g. due to distortion - most fire separating elements fail the fire test due to gaps forming because of distortion, not burn-through).  They can be extremely sensitive to the smallest variation in constructional detail (e.g. fixing type and spacing, joint detailing etc)

The difficulty is compounded when the element is also load-bearing (e.g. it's a floor).  A good example - we had a case where someone had built a timber load-bearing partition that needed 60 mins fire resistance using the board details from a tested 2-hour non-loadbearing partition.  They argued that the boards would stay in place and protect the studs for at least 60 mins, hence all was fine.  We refused to endorse this approach, & eventually the construction was fire tested.  The 'two-hour' non-loadbearing board make-up did 40 mins in the load-bearing construction!

Like I say, I know of no published and verified methodology of doing what you describe (i.e. demonstrating that a fire separating element will stay in place and effective for the length of time required for full 'burn-out' of a compartment).  I've seen people try, but their approaches have never stood up to technical scrutiny, in my experience.

There's probably a PhD in this, if someone were so inclined...!

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Fire Safety / Example 'Managed Use' storage in communal areas policy/notice!!!
« Last post by anhphuong on January 15, 2019, 04:39:01 AM »
Hi All,

Would anyone be able to point me in the direction of some sample procedures/notices which may have been established for properties where the above approach has been adopted?

Thanks
8
Technical Advice / Heat calculation
« Last post by lyledunn on January 10, 2019, 06:56:51 PM »
If one knew the geometry and constructional make up of a room as well as the fire loading within, is it possible to predict the effect on the enclosing elements with any degree of accuracy?
I am thinking of a room, totally enclosed in 60 min fire resistant plasterboard and fitted out with loose furniture and soft furnishings. I am interested in the response of the plasterboard, especially on the ceiling.
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Fire Safety / Re: Gas and MCPs.
« Last post by lyledunn on January 10, 2019, 06:45:50 PM »
It would be up to others, competent to do so, to identify the zone classification in and around equipment. It would be on that basis that one would select and erect appropriate electrical equipment.
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Fire Safety / Re: Gas and MCPs.
« Last post by Dinnertime Dave on January 10, 2019, 03:26:53 PM »
[quote
Would we consider the risk of a gas leak of adequately maintained equipment is so low as to be quite trivial?
[/quote]

Yes.

I would only expect to see IS equipment in areas where there would be under normal operating conditions a risk of a spark igniting flammable vapours. E.G Petrol store.
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