Author Topic: fire alarms (Read 22317 times)

potter 2 · « **on:** November 17, 2003, 03:59:03 PM »

a range of ground floor only shops has 2 floors of flats above,the shops have been put into 1 hour FR boxes but there isnt complete vertical separation between the shops up to the roof,would the fire alarms in the shops have to be linked into the flats area,the flats have thier own independent stairwell access,does building regs or bs 5839 give the answer

Guest · « **Reply #1 on:** November 18, 2003, 02:26:00 AM »

This is always tricky. The purists would say as per BS 5588-1 that they should be interlinked as this is a mixed user development. In practice to do so is a major pain and gives all sorts of practical problems. Better to have a good degree of separation from shops and flats and treat as speparate. No point in looking at Bs 5839-1 as it is not a fire safety code.

Ken Taylor · « **Reply #2 on:** November 18, 2003, 09:28:57 AM »

Can the shops write into their fire plans to notify the occupants of the flats above by some safe means in the event of fire?

Brian Catton · « **Reply #3 on:** November 18, 2003, 01:48:58 PM »

I think to answer this question we have to go back to the basic reason fire alarms are there. (Excuse the blatently obvious) To give warning of a fire that could prejudice the lives or means of escape for persons in a building.

Now if we look at the term building we must follow Colin's line of thinking on separation. A.D. B gives a definition of separated part of a building in appendix E on page 129 This talks about a compartmet wall running full hight on a vertical plane. This would obviously not apply to your building.

If there is a need because of the assessed fire risk, (including fire loading, exposure hazard by vertical spread etc) to give warning to the flats above an external sounder linked to smoke detection in the shops would suffice.

Ken your idea would work during the times that the shops are occupied and under the proposed solution above the occupiers of the flats would still need to be informed.

I am assuming there is no detection in the shops.

Colin's advice that separation is best is very simple but may not be achievable.

AnthonyB · « **Reply #4 on:** November 18, 2003, 04:18:44 PM »

A recent development we do weekly testing of the fire alarm system at consists of flats above commercial units (proposed & actual use retail/leisure/restaurant).
There is are three stairways & corridors purely for the flats.

The flats have an addressable system with detection & sounders to the escape routes, and the current occupied unit has a conventional system with a relay allowing mutual alarm either way. Empty units are covered by the flats system that has been extended into the area.

The benefit was demonstrated by an arson attack on an empty unit, which set the entire alarm system off, allowing the fire to be caught reasonably early. Or at least thats what should have happened as if it wasn't for one of our staff walking home past the place & hearing the panel buzzer & then smelling the smoke the fire would have grown further before noticing as there was no monitoring link and the alarm didn't work properly- our weekly tests found that 99% of the sounders (which were in the form of sounder bases to detectors) didn't work & only the seperate sounders went off. As these were only in the basement & empty units, it was of little use to the occupants. It took 2 months & a change in managing agent to fix it.

So if you do go down the technical route with alarms, good maintenance & competent servicing is important (the system supposedly had a 100% test & service after the fire, but they never noticed the sounder bases didn't work)

Ken Taylor · « **Reply #5 on:** November 18, 2003, 05:02:52 PM »

I'm with you on this one, Brian. I could have put the question better if I hadn't been in such a hurry to get out of the office - but the point is that if the people above will be at risk (which presumably is the case without adequate fire separation) they need to be notified ASAP whenever a fire occurs and this needs to be done in a safe manner. Given that the answer to my question will be 'No' in the situation you describe, sounders that will perform this task and be heard by the occupants of the flats should serve this purpose without the need for linked alarm systems.

wee brian · « **Reply #6 on:** November 19, 2003, 11:46:23 AM »

The problem with providing linked alarms in domestic buildings is that people don't take kindly to being woken up at 2am because their neighbour is cooking chips/toast/having a cigar etc etc.

This can result in the system being vandalised by the occupants.

Adequate seperation should be the first priority. Linked alarms should only be considered as a last resort and where there are only a couple of flats involved.

AnthonyB · « **Reply #7 on:** November 19, 2003, 11:01:17 PM »

But thats is only a problem if you put detection inside the flats & if it is smoke heads.
The two mixed use developments I've been to with common & linked alarms neatly get around this in two ways

a) One has smoke detection with sounders to the corridors & stairs only and not inside the flats
b) the other (better) layout has smoke detection with sounders to the corridors & stairs, heat detectors inside the flats to detect fire when unoccupied & seperate self contained 240V smoke alarms inside flats to provide life safety alarm when occupied

Ken Taylor · « **Reply #8 on:** November 20, 2003, 09:25:21 AM »

Do the shops below also have AFD to operate sounders on the stairs, etc to warn the flats?

potter 2 · « **Reply #9 on:** November 20, 2003, 11:16:51 AM »

thanks for these ideas...some shops have detection to cover mezz ,so i can insist they are maintained and some,just because they want to put in detection therefore they could lose them later.?especially as some will be fast food outlets
i cant get true vert separation as corridors run the length of the flats. i have anticipated all sorts of problems if they are linked,testing,false alarms ,resetting shop alarms at 4 am..i quite like the sound of external sounders on the shop (no pun intended) but in a shop with no detection ,on sunday night ,fire could develop unseen for some time and maybe breach the FR, So hows about separate fire alarms,external sounders plus insist on detection as Bill reg application to compensate lack of vert separ..do you think it best to also link the flats to the shops ,maybe again just on the external sounder

Guest · « **Reply #10 on:** November 21, 2003, 12:58:21 AM »

We have advised buidling control on such submissions, recommending at most heat detection in the flats and a connection to an ARC as a mandatory part of the approved system. If there is a need to evac the flats the FB can then do it.

Ken Taylor · « **Reply #11 on:** November 21, 2003, 12:45:04 PM »

I'm confused now, Colin. Are you saying that there should be a plan for fire brigade evacuation of the flats rather than self-evacuation upon alarm where fire separation is inadequate?

Guest · « **Reply #12 on:** November 22, 2003, 05:10:41 AM »

Depends on the nature of the separation. Its what happens in purpose built flats and there is no early warning from AFD. With early warning there would be compensation for reduced separation.

Ken Taylor · « **Reply #13 on:** November 22, 2003, 10:54:59 PM »

I think if I was in one of Potter 2's flats above the fast food shop and they'd left the fat-fryer on, I'd want the earliest warning of the inferno below!

potter 2 · « **Reply #14 on:** November 23, 2003, 01:55:05 PM »

with what the flat dwellers have in their veins or lungs already the smell of a few donners isnt going to worry them.if they notice it at all,,or to that matter a fire alarm sounder ,

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Author Topic: fire alarms (Read 22317 times)

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