Full evacuation of appartments

[AM]

Under what circumstances would you accept a full evacuation of a new build appartment block to compensate for lower provisions elsewhere? I've been asked to comment on a strategy which states that as a full Pt 1 alarm system is proposed, everyone will leave when the alarm is raised and therefore double door protection to the stair is suitable without ventilation. The head of a staircase also has to be crossed to reach an alternative.

I think this assumption is flawed, and that people in flats won't leave immediately,(esp. a few years down the line when there's been a few false alarms) and that's why the fire strategies for such buildings are as outlined in ADB.

Any thoughts?

[CivvyFSO]

I fully agree for the same reasons as you. Look at the pre-movement times for sleeping risks in PD7974-6. >20 minutes from hearing the alarm in many circumstances.

There is also the position to consider that by evacuating people are you actually placing them at more risk than if they stay in their compartmented flat?

Also, there would possibly be venting required for firefighting depending on the height of the building.

[jokar]

I agree as well.  There is also the provision of evacuation aids for people with disabilities, to consider as well as the movement of children.  I would be interested to know what the strategy states about babies and infants being left outside in the cold, wet and snow.

[Midland Retty]

I agree with all replies so far.

However you mentioned that the evacuation strategy is due to "lower provisions" elsewhere. What exactly are we talking about here?

If the project you have been asked to make comment on is still in the design stages then I would try to push for a stay put policy - and clearly the fire precautions would need to be geared to support that of course.

But it does depend on what the designers are trying to do,and the rationale behind their brief.

In my opinion the problems with a full evac strategy are as follows :-

1) False alarms - whilst modern fire detectors are 'intelligent', could false alarms still be an issue? and if so how might that fuel compliacency amongst residents? Is the proposed fire alarm system suitable?

2) Time taken for residents to react to an alarm. If response times are slow then it follows that as the time to react to an alarm increases, the amount of time the means of escape will remain clear and available decreases. What sort of fire seperation will incorporated into the building ?

3) What provisions have been made for the elderly and less abled residents? Remember that a resident may start their tenancy fit and healthy, but their circumstances could change. Alot of designers I speak to say " Oh we only rent out to able bodied tenants in our blocks" Trouble is people get older, their health deteriorates, people fall ill, or have disabling accidents etc etc

4)Type of tenancy - who will live in the apartment block? Will it be a general lease block? Will it house vulnerable people? Will it be an exclusive block for affluent people? These all have a bearing and are important factors to consider.

To my mind keep it simple, have a stay put policy and conventional apartment block / flat design

[Mike Buckley]

Another aspect that needs to be considered is access for firefighters. If the assumption is made that the stairwell may fill with smoke but after the residents have evacuated ( all fully able bodied, fit etc.), the fire fighters are not going to be able to use the stairway to access the area of the fire and if they try to set up a bridgehead in the stairway it will soon become untenable. 

[Tall Paul]

I agree too.  The ventilation required in a stairwell is Openable Vents, not Automatically Openable Vents, which means that the windows or head of stair ventilation has to be manually operated.  As I understand it the ventilation is there to allow fire-fighters to work in a clean environment and has little to do with evacuation.  The provision or otherwise of a Part 1 system would therefore not provide suitable compensation for the removal of the ventilation

[wee brian]

There's an article in Fire Safety Management Mag covering a study in OZ.  They use simulatneous evac for flats but the study shows that it doesn't work very well>

[Clevelandfire 3]

Full evacuation would be unwise and to be honest I dont see how it will work in the real world.

[nearlythere]

Under what circumstances would you accept a full evacuation of a new build appartment block to compensate for lower provisions elsewhere? I've been asked to comment on a strategy which states that as a full Pt 1 alarm system is proposed, everyone will leave when the alarm is raised and therefore double door protection to the stair is suitable without ventilation. The head of a staircase also has to be crossed to reach an alternative.

I think this assumption is flawed, and that people in flats won't leave immediately,(esp. a few years down the line when there's been a few false alarms) and that's why the fire strategies for such buildings are as outlined in ADB.

Any thoughts?

AM. Why are there lower provisions in a new build? Are the developers trying to fix a problem with the building design and see full AFD as a cure all?

[AM]

The building is an existing two stair block, which is being extended beyond one on the stairs, creating a dead end where that head of stair would have to be crossed. The developer has put the argument forward that suitable smoke control will be provided as the flats have internal protected hallways creating 'two door protection' to the common corridor and therefore vents in this area is not required as no smoke will enter and there will be a full evacuation so every one will be out of the building. A vent has been provided in the stair, which I don't think wil provide any benefit.

My arguement is that the BRe found that most internal doors has their closers removed, so that level of protection can't be guaranteed, and the time delay in respect of the alarm and response could mean that some evacuees could be interacting with fire fighters (so the door to the flat on fire could be open) without suitable smoke clearance. Local Acts are muddying the waters aswell.

[CivvyFSO]

The internal doors do not require self closers anyway IIRC.

Unless the travel distance within the flats is <9m then the protected entrance hall would be expected anyway.

The area where persons have to pass through the head of a stair could simply be seen as a single stair condition.

How many storeys do you have, and how does it line up with diagram 9(b) of ADB?

[nearlythere]

The internal doors do not require self closers anyway IIRC.

Unless the travel distance within the flats is <9m then the protected entrance hall would be expected anyway.

The area where persons have to pass through the head of a stair could simply be seen as a single stair condition.

How many storeys do you have, and how does it line up with diagram 9(b) of ADB?

And what height is the uppermost floor above ground level?

[AM]

6 floors.

I looked at the design from a single stair POV, and the TD's are OK, but there is no ventilation in shaded area of Diagram 9b

[CivvyFSO]

To be honest I think we could all go on finding fault with this for days to come. When you get the consultant/risk assessor people agreeing with us fire service types - that is about the best consensus you can get as to whether something is right or wrong.

[Northern Uproar]

Hate to bring this issue up again (I can't log on with my original user name), but the provision of facilities in common areas still seems to be causing problems: I'm currently dealing with a new purposed built block of flats, and both the Building Control officer and the Fire Service are insisting on detection in common areas to intiate a full evacuation and disabled call points near to the staircases, apparently it's 'good practice' and their communications to me suggest the 1 hr compartment and stay put policy is something that we've come up with, and that such a policy may cause the occupiers issues with the FSO.

Any thoughts?