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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: JimK on March 21, 2011, 04:37:26 PM
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I'm trying to find the correct position for smoke detectors in a 3 storey block of flats. Where should the detectors be - I think it is just the circulation space in the flat, but I am concerned about whether there should be any detectors in the stairwell?
Any help will be much appreciated.
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http://fire.org.uk/forum/index.php?topic=5313.0
You should have a read through this thread and realise what an ambiguous question that is......!!
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Not really ambiguous David when it comes to flats.
Its simply a judgement as to whether, in the event of a fire in any one flat, the building is safe such that apart from the flat involved in the fire, the occupants of other flats may stay in their flats instead of evacuating the building.
This judgement comes from comparing the design, nature and layout of the building with the standard design benchmarks for purpose built flats, which are designed with sufficient compartmentation and fire protection measures to make this "stay Put" policy a safe option for most forseeable fires that may occur. There have been design documents of this type since the second world war right up to current building design documents such as the Building Regulations Approved Document B.
However buildings that were designed to be used on this basis can suffer over the years as workmen and contractors put in new wiring, pipework, heating etc and knock holes through the solid compartment walls and floors thus creating passages for fire and smoke to spread.
Generally purpose built blocks of flats should not need any form of fire detection and alarm system in the common areas, each flat should have its own stand alone system of mains powered domestic smoke alarms. Depending on the layout it might even be a single alarm in the entrance lobby to a flat where the bedrooms are closer to the flat entrance door than the lounge or kitchen.
If because of design weaknesses it considered necessary and appropriate to provide a fire detection and alarm system in the common areas to support a full evacuation strategy, then it should not be a system based on domestic smoke alarms, but a full system designed, installed and maintained to B5839-1. If people need to be evacuated from the building then this alarm needs to be sufficiently audible to wake them up at night, so a sound pressure level of 75dB at the bedhead would be required. In such circumstances often each flat still has its own self contained domestic smoke alarm but this is supplemented by a full detection nd alarm system in the coomon areas, with smoke detectors in staircase and lobbies, and a heat detector and sounder in each flat.
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I'm trying to find the correct position for smoke detectors in a 3 storey block of flats. Where should the detectors be - I think it is just the circulation space in the flat, but I am concerned about whether there should be any detectors in the stairwell?
Any help will be much appreciated.
Jim I think your question has been misinterpreted.
If you want to check the distances, siting and location of where detectors are sited you need to consult british standard 5839. That will tell you not only where detectors and fire alarm systems are required, it will also tell you the type of detector required as well as how far from walls upstands and other features detectors should be located. Unfortunately unless you have access to British Standards this may be difficult.
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Thanks Kurnal and Clevelandfire, if I understand correctly, it is down to the design layout, good compartmentation and fire separation and also the risk assessment. With a good design etc it should be ok to have a domestic system installed in the circulation space (corridor) in the flat.
Thanks for your help. Jim
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With a good design etc it should be ok to have a domestic system installed in the circulation space (corridor) in the flat.
Not really Jim. Good design and good construction are two different things. A building designed to B Regs will probably not end up being built to B Regs. Hence you should survey as best you are able to hunt out weaknesses in the compartmentation and separation and there will most likely be plenty.
I have learned to distrust Building Control completion certs which many accept as a suitable control measure for many aspects of a FRA.
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Kurnal... the reason I say "ambiguous" is because I thought we've concluded previously that a block of purpose built flats doesn't or shouldn't technically need a fire detection system within the common parts.
Just a part 6 system within each dwelling space.
Although JimK says "block of flats" I wouldn't have concluded they were purpose built or modified or classified as an HMO, all factors that would affect the need and the standard of a fire detection system in the common stairwell (in this case)?
Or have I really mis-interpreted ??! :o
Think I'll stick with office blocks....!!!