Smoke detector in void

[lyledunn]

We are installing a ceiling in a small shop unit which is basically a concrete box on the ground floor of a multi-storey car park. As far as I could see one could use the shop as a furnace without affecting any other part of the building. Anyway, BC require me to fit a smoke detector in the void formed by the ceiling which we intend installing below the concrete slab but only if the void exceeds 800mm. I can find nothing that refers to this requirement other than in 5839-1 which requires detectors in voids exceeding 800mm for L1 systems. These premises are connected as a zone in the main car park panel. The existing arrangement is one detector and two MCPs.
The shop unit is only 20mx10

[kurnal]

What is the fire alarm specification for the building? Is the Landlords system L1 ? Is the building sprinklered?


Here's an earlier thread on this topic. Ignore Wiz's infatuation. He soon found me out when we took a room together.

https://www.crisis-response.com/forum/index.php?topic=1644.0

[lyledunn]

Thanks Kurnal. At least I learned something from Wiz. There is a comma missing in the wording of the requirement in 5839 that led me to believe that ASDs were only required when L1 systems are employed. So I now know that if smoke detection is required below the void then if the void exceeds 800mm, it is also required in the void (with certain exceptions).
That really doesn't change things as the little unit appears to be a concrete bunker in which you couldn't put sufficient fire load to warm your backside. It is going to be a Spanish tapas take away so if a fire alarm is required a category M would suffice and thus detection in the void would not be required.
What confuses me is that the car park alarm extends in to the unit and both automatic detection and MCPs are provided, for what reason, I do not know. I can't imagine that an alert in the unit would warrant evacuation of the complete car park complex.

[lyledunn]

I should have pointed out that this shop unit is accessed direct from the street. There is no need to access the car park other than to access bins. The car park sits on top of the shop unit.

[kurnal]

It does sound a confused situation, I gather from what you say the shop unit has two fire alarms, the landlords system has both MCPs and detection in the shop and the BCO is requiring you to install a seperate alarm system including void detection in the shop. Am I reading this right? If so it sounds a right mishmash - it's ok to have seperate alarms linked to operate together but there should never be duplicate call points, detectors etc.

Overall to me it sounds as though the shop unit is part of a larger building comprising the car park. If it should be that the car park for reasons of life safety has an L1 system then it might be reasonable to expect all spaces including the ceiling void to be covered. But this would be a very unusual situation for a car park! Other than for that scenario it is difficult to understand why the BCO should be asking for void detection. Remember the BCO can only require work to be done in respect of life safety, property protection is not their remit.

There is information and guidance in BS5839-1 in respect of risk assessment of voids, including the category of system, the presence of combustible materials in the void, whether the ceiling is fire resisting etc.

[col10]

Could be a standard ask because it is part of a shopping mall.  BCO may be aware that it will be a landlord's requirement.  A solution could be to use perforated ceiling tiles.  At a size of 20 x 10 you could argue that the void needs a cavity barrier.

[lyledunn]

There is no stand alone fire alarm in the unit. There are 2 MCPs and 2 ASDs any of which operate set the alarm off in the whole building. The car park is around 10 years old. Putting ASDs in the void satisfies 5839 but would appear to make a bad situation worse!

[lyledunn]

I tried to track down the purpose of the provision in the unit and why it was connected to the main system. Landlord has no original documentation, agent just says system requirements are responsibility of tenant and BC seem reluctant to look at their file for the building. For this unit to be regarded as appropriately separated am I correct in saying that all aspects of appropriate compartmentation should be in place, which I think they are?
I deal a lot with planning permission where I can access plans, submissions, proposals and other documentation relating to any project that has gone through the application process. Wouldn't it be great if BC documentation was also so freely available!

[col10]

It is, Freedom of Information Act.
However the Act does not apply to private sector BC and LA BC may claim commercial interest exemption.
But what use is documentation anyway?  Compartmentation could be breached despite what is says on a drawing / documentation.  If the ceiling is down due to a shop fit, best thing is to get your head up there and see if there are any holes in the compartment floor / walls.  you need to be speaking to your BC Surveyor.

[lyledunn]

The BC surveyor wants me to provide plans of the original build so that he can assess. Strange request since his local authority were the ones that assessed the original plans. If, to gain approval, the original plans did not indicate the need for ASD in the individual units then I would have a better handle.

[col10]

Your plans based on your survey might show effective compartmentation. The plans in the LA archive , if they have any, if they are legible, in various formats, may  or may not show compartmentation, which may or may not have been built as plans and may have changed since being built and cant be relied on , so what use anyway.