Detection in office block

[K Lard]

Two storey office block, two way travel in corridors with protected staircase at each end. Having the fire warning system renewed due to age, the old system was type M with no detection. The fire alarm company insist that detection is required because there are no vision panels in the office doors so that persons cannot see if the corridor is smoke logged when the office door is closed. Can't find any reference in the guidance  - only detection required for dead end condition without Fire Resisting doors. Is the fire alarm company justified in insisting on detection?

[Phoenix]

If the alarm company is talking about doors from the rooms to the corridors then they are incorrect.  It sounds like they are getting muddled up with inner room requirements.  If they cannot be trusted to get this simple fact right then I would not trust them to install a system.

The base requirement for such a building is a type M system, as currently installed.  However, a fire risk assessor might recommend some detection coverage.  If the building is occupied by people on the upper floor when the lower floor has been vacated, for example when someone is working late on the upper floor, then it would be beneficial if the person on the upper floor knows about a fire that starts on the lower floor.  Therefore, many people believe that an L4 system is ideal for a building such as this.  That is, detection in the escape routes only.  L3 might be over the top and would probably require detection in nearly all, if not all, rooms.  An L4 system would give flexibility to the use in the building by providing early warning for people when other people are not there to raise the alarm.

An L4 system, ironically, would also deal with the issue of smoke getting into a corridor and affecting people's means of escape from the rooms (as alluded to by the alarm engineers) - but this is not essential and no UK codes recommend it - by virtue of the fact that experience has demonstrated that this potential problem is seldom, if ever, realised.

I recommend looking for another quote and considering the benefits of an L4 system (it probably wouldn't be required if everyone who works in the office building gets in at the same time and leaves at the same time, for example).  Consider also coverage for inner rooms and dead ends.

Stu


 

[nearlythere]

Fire alarm installers are in the business of making money by selling systems. The bigger the system the more money they make. The level of fire warning systems is by risk assessment with 5839 being the benchmark.
Never ever heard of detection needed because of solid doors to corridor.
And as Dot would say " where are the bodies?"

[Davo]

Hi KLard

What does the FRA say?

davo

[AnthonyB]

It's nothing to do with the fire alarm company, unless they are doing the full FRA. All to often instead of commissioning a competent FRA, RP's ask the fire alarm company, the extinguisher company, etc and end up with far more than actually needed.

An office block could happily stay Category M (especially if single occupancy) or perhaps L5/M if there were some specific risks (e.g. inner room).

If multi-occupied there could be differing times of use in various parts of the building with a greater chance of a fire developing unnoticed (as happened in the multi fatality fire in 1977 at Murray House in Manchester) and so AFD would be a consideration, usually L4, sometimes L3 - depends on the layout and risks.

I'm sure Mr.T will be along to clarify if required!

[K Lard]

Thanks for the replies they have been really useful. As far as the FRA is concerned there is nothing to indicate that detection is required. However may consider L4.

[colin todd]

I think not Tony.