New build 4 storey flats

[jakespop]

I have been asked to advise on brand new 4 storey single staircase building. Designed as luxury apartments but will be let to students initially. Fully sprinklered. Automatic venting to staircase. I was expecting a mixed alarm system and potentially a stay put policy. However installers have gone against initial design and have installed L2 system throughout which leads me to feel there may be false alarms regularly. As only one system, I was of initial opininon that there should be total evacuation every time alarm actuates.
Another suggestion is to install ozone detectors instead of standard smoke in Lounges to try and reduce false alarms.
Any comments appreciated.

[lyledunn]

It falls on the designer to ensure that measures are in place to reduce false alarms. Personally, unless delays are built in such as with the alarm sense detectors or the hush facility arrangement by C-tec or indeed an analogue addressable system is employed then I fail to see that the arrangement is compliant.
Mixed systems have disadvantages which have been largely overcome by the systems noted above and are probably just as easy to install, if not more so!.
To be honest, I see the sort of system to which you refer on a regular basis. No body seems to give a toss as long as the paperwork is available. I am dealing with a very similar situation at this very moment. As part of a Licensing Scheme requirement, I detailed my concerns regarding the likelihood of false alarms in one installation on an Inspection Report and sent it to the Enforcing Authority some time ago. Seems at the time they just regarded it as a Certificate. Following several false alarms, tenants complained, solicitor involved and of course the big stick is out for any one remotely concerned with the system! The system was only about 10months old when I inspected it. Contractor, whoever he was, did not issue certification!
Regards,
Lyle Dunn

[kurnal]

If the building conforms to the ADB benchmark and is suitable for a stay put policy then there is little to be gained by then installing an L2 system.

Each flat will need smoke detection in accordance with the ADB and BS5839-6, most likely a Grade D system type LD3.

An addressable BS5839-1 system , category L2 coviring the common areas with detector sounders  also in flats can be configured to emulate a  stand alone LD3 domestic system but this approach brings with it several big disadvantages- who will take responsibility for the panel?someone has to manage the panel, check for faults, re-set the panel after activations and engineers access has to be gained to each flat to maintain the detectors. I have seen a number of these systems vandalised beyond repair by frustrated tenants.
Finally if you do decide to stick with it, consider what advice you will give tenants in the event of an alarm in the common areas.

Check for signs of smoke?
Call the fire brigade?
Pass through the smoke or stay in your flat and out up with the noise till someone comes to take control of the system?
Who will be responsible for re-setting the panel? The fire brigade most likely will not.

[CivvyFSO]

Call me a cynic but I think the installers are trying to make a quick buck there. Stuff like this will often get through because of a simple lack of knowledge with both developers and some building control bodies.

It might also be worthy of note that many approved inspectors seem to have a standard set of requirements for part B, among them "Fit an alarm to BS5839-1, Category L2" This is regardless of the purpose group or layout.

I have even seen this suggested for a submission where they were simply removing an escalator from a shopping centre that already had an L1 system. They also included "Signage to signs & signals or BS5499" etc. Now I might be wrong here, but I do not think that there is a standard sign for "Escalator gone, do not stand here and expect to be taken to a different floor"

[jakespop]

Thanks for comments. The problem with now changing detectors to reduce false alarms is that this effectively increases risk to occupants in flats. The owner is now going back to installer to push for the original design to be implemented. I suspect we will end up with a mixed system. Interesting comments about who will take charge etc when alarm goes off. This the same issue in a lot of multi occs with absentee Landlord. What is the answer??
   

[Phoenix]

"What is the answer?"

Well, in my opinion, there is no single answer to the broad issue you put forward, each case will have its own set of answers.  So I would just concentrate on one case at a time.  And in this case, we have your four storey building with an L2 system. 

Provided that there is confidence in the compartmentation and correct protection to the single staircase I don't think there's any point beating about the bush.  I'd advise them to rip the L2 system out and put in the recommended part 6 system as kurnal specified above.  It's their own stupid fault. 

Bodging up some protocols to manage the L2 system now is unlikely to get rid of the problems that the installation will generate over the years.

Don't think that going to a part 6 system from a part 1 L2 system is increasing the risk to the occupants.  It's much better to have a fully functioning part 6 system in each flat than to have a part 1 L2 system covering the whole building with all the sounders stuffed up with socks.

Stu