false ceiling in office

[mosh]

A large office used to be open plan, but has now been subdivided into small offices and a corridor.

There is a false ceiling, which has not been subdivided and is open throughout.

Am I correct in saying that even though it was acceptable beforehand (when it was open plan) it now needs to be subdivided? Would the compartmentation be required between every office, or just between the corridor and offices?

Thanks

[lyledunn]

See page 76 in ADB Vol 2

[mosh]

Thanks for your reply. I checked your reference, which seems to be a diagram describing cavities, and doesn't seem to address my question. Is that what what you are referring to, or am I missing something?

[Dinnertime Dave]

The size of the ceiling void has not changed. Why do anything?

Has the risk within the void changed?

[mosh]

The size of the void has not changed.

However, it could now take longer for a fire to be detected. Initially, when it was open plan, a fire would be noticed by one person and everybody would immediately leave.

Now that there are multiple offices, a fire could start in one (unoccupied) office, but the other offices might not be aware of it until the fire has spread through the ceiling void into the escape route.

So the question remains, is it therefore necessary now to provide compartmentation above the false ceiling, to protect the escape route (and between offices)?

[Dinnertime Dave]

If your concern is a fire in an unoccupied office. Detection in the offices is the answer.

If the offices are serviced offices ADB from memory recommends an L3 system. This should have been done on conversion.

If they are under the control of a single occupier, is there two directions of travel? If there is then fire resistant isn't required.

If the offices have not been subdivided using fire-resisting construction then subdividing the void is is pointless.

[lyledunn]

Thanks for your reply. I checked your reference, which seems to be a diagram describing cavities, and doesn't seem to address my question. Is that what what you are referring to, or am I missing something?

I meant the whole article on cavities should be read, not just the diagram. Sub-dividing an existing office space is notifiable and a BC application should have been made. I appreciate works like this often go under the radar.

[mosh]

Thanks for your replies.