Author Topic: Audibility in flats for evacuation  (Read 188 times)

Offline AnthonyB

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Audibility in flats for evacuation
« on: May 11, 2020, 07:56:04 PM »
We are all used to the sound pressure levels for evacuation of sleeping persons, 75dB bed head where a Part 1 system is applicable and 85dB at the bedroom doorway where Part 6 applies (& often used as a variation for Part 1 systems added to blocks of flats being changed to full evacuate from stay put).

What does everyone think about full evacuate systems in blocks of flats where the only measured audibility is 83dB at the flat front (fire) door (and by implication far less at the bedroom due to distance and walls/doors?

Apparently Merseyside FRS are stating this is enough for any blocks of flats needing to evacuate.....I can sympathise with the 85dB bedroom door variation where technically it should be 75dB bedhead as flats common systems should be Part 1, but this surely is a step too far?
Anthony Buck
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Offline Graeme

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Re: Audibility in flats for evacuation
« Reply #1 on: May 11, 2020, 08:55:30 PM »
Depending on what the doors are made of the dB(A) isn't going to be any more than 60 in the inside hallway - add fixtures carpets , TV's , music then its a bit pointless imo
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Offline Fishy

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Re: Audibility in flats for evacuation
« Reply #2 on: May 12, 2020, 01:21:00 PM »
Though it's not a 'fire alarm' system per se, the recently-published BS 8629: 2019 "Code of practice for the design, installation, commissioning and maintenance of evacuation alert systems for use by fire and rescue services in buildings containing flats" recommends that the 'evacuation alert' SPL, measured at the doorway of each bedroom (with the door open), should be at least 85 db(A) and it should be no less 60 dB(A) in any of the habitable rooms.  Not sure whether this is the type of system that's being discussed, or it's one of the BS 5839 variants?

Given that this is National guidance for a system with this fire safety function, I'd suggest that anyone would need a very good reason to say that SPL criteria far less than this would be acceptable?

I'd love to see the Merseyside FRS guidance - or perhaps it's just something an IO came up with and has never been written down?

Offline AnthonyB

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Re: Audibility in flats for evacuation
« Reply #3 on: May 12, 2020, 06:14:32 PM »
It's mitigation for structural defects in a part occupied unfinished resi development - apparently it's even in an e-mail from them (trying to get hold of it).

Today heard from a builder that does care home work that in the existing older care homes he works at that where the alarms are not goods enough he's allowed by the FRS to stick wireless linked Grade F detection in as a medium to long term solution.....although it could be just the usual rumour machine in this case!
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Offline Fishy

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Re: Audibility in flats for evacuation
« Reply #4 on: May 14, 2020, 09:04:57 AM »
I do wish people would realise that just because someone from a fire and rescue service has said they don't object to something, that doesn't make it right, nor legal, nor does it protect them from prosecution under the RR(FS)O, Building Regulations and/or CDM.

Following fire service advice just makes it less likely that they'll carry out enforcement action on you, and that only applies to the legislation they enforce, of course!

Offline AnthonyB

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Re: Audibility in flats for evacuation
« Reply #5 on: May 14, 2020, 06:47:52 PM »
Yes, but RP's will take it as gospel, especially if it saves them money and inconvenience and after all they aren't going to be prosecuted unless they have a fire - and no one has fires do they!
Anthony Buck
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Offline colin todd

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Re: Audibility in flats for evacuation
« Reply #6 on: May 20, 2020, 12:41:58 AM »
Fish Face, you are such a heretic. Now, a wee pub question for you. What would Holroyd have said in answer to Tony's question and where did he get that answer from?
Colin Todd, C S Todd & Associates