Audibility in flats

[colin todd]

Big Al, I do not have advice to offer the observation point, because I regard myself as an angel who fears to tread. I do consultancy all day, usually on a good day with proper information on which to give advice.  I have no real desire to solve problems for buildings which, as Tony says, you have inadequate information about.

However, for your eddification, the 75dB(A) comes from research with American students in the 1960s, while most sleep researchers (no not the old ccodgers on the park benches in Matlock) could tell you about the sound pressure levels to rouse you from sleep in your own home. I was not aware you were familiar with sleep research , such that you would be aware of it. Was this gained in the beds in Matlock fire station or the effect on Mrs Kurnatowski of your response to her question as to whether you had a nice day in your tower block office that overlooks the Derbyshire dales.

With regard to the level of detection when the ceilings are naff, if fire is beginning to cause lath and plaster to fail, it must be fairly severe, but hopefully residents threatened would still be able to use the common escape routes if warned by a H/d before the FED failed.

Hope this helps.

[kurnal]

There are no beds at Matlock Station Colin and there never have been. It has been a day staffed station since 1956 and the fire fighters have been wakened instantly in their homes by their pocket alerters the sound pressure level of which is covered by a JCDD spec. But in my day they always slept with one eye open whilst on their 96 hour tour of duty. Can you imagine that Colin- 96 hours at a stretch? After a busy tour it would take big ben to wake them. Mind you it has been said your one day courses felt like 96 hours....

I note a new edition of BS5839-6 has just been published, I will buy a copy and eagerly look for the undoubted new references to sound pressure levels with mixed systems.

[David Rooney]

It is widely taken as custom and practice by many alarm engineers and most electricians  that in a mixed system, if 85db at the bedroom door measured with the door ajar  is good enough to wake you in your own home then the same alarm level is all that is required from the pt 1 communal system.  

The crux is whether this should be viewed differently when there is a duty of care toward the occupants of the dwelling.

I agree with that Kurnal, and that is my view ....

However, your last sentence is the important part, in that we have a fire officer that has demanded 75db at bed head on an Enforcement Notice.

Now a few of our "millionaire home owners" didn't want a detector in the hall way, let alone sounders in the bedrooms..... and the first time this system goes off they won't be ringing the Fire Officer ....!

[kurnal]

Since the BS does not offer clear  guidance in respect of this very cmmon scenario, an appeal against the enforcement notice might be useful as a first step to achieving a  precedent and / or a consensus.

From the opposite point of view we see very many new blocks of flats, some with self contained part6 and  some with part 1 systems installed in the communal areas (nothing in flats) where no communal areas fire alarm is required.
I am often told by builders that they are put in because  approved inspectors employed by NHBC require them in all blocks irrespective of the evacuation strategy. I dont know if this is correct. (I am not referring to detectors that control the ventilation system.)

[Golden]

I found one shiny new block recently with a manual alarm system but no sounders anywhere - the only alarm it sounded was a pop up on the concierge's computer screen; the concierge worked 8-6 weekdays! I assume if he happened to be at work he was then going to run around all hundred flats on ten floors knocking on all the doors.

Its definitely worth asking the question of the fire authority as they may just have cold feet with respect to an issue with compartmentation that may even be easier to resolve. There is nationally approved guidance with respect to this issue and a number of people are starting to get wobbly because of an isolated incident where, by and large, a badly designed and poorly built/maintained building did its job for a considerable length of time.

[colin todd]

Well said, Silver.  far from causing people to panic about PBBF, Lakanal Houese would suggest quite the opposite.

[kurnal]

Did anybody see BBC Breakfast this morning which featured Dave Coss from Derbyshire Fire and Rescue Service explaining his work with Newcastle Uni researching why children, especially boys, are not woken by smoke alarms? I saw the first segment but had to leave before the second segment.

[AnthonyB]

I saw a very short bit of that too, he was saying that smoke alarm sounders using the same frequencies as the Mosquito 'anti-youth' sound systems may be worth trying.

For those unaware of Mosquito: http://en.wikipedia.org/wiki/The_Mosquito