Retail Unit Seperation

[GB]

My client has a 2000m2 retail unit in Scotlan which he wants to sub divide into 2 1000m2 units.
The existing unit is sandwiched between two other similar units with compartment walls beyond the roof covering.
The units are non sprinklered.

We want to provide a seperating wall to divide the units into seperate occupancies of medium fire duration (60 minutes) but for the seperating wall not to continue above the roof level. It will stop at the underside of the ceiling / roof with 1.5m either side of the wall being fire boarded with 60 minutes FR.

We propose to install an interlinked, monitored L2 fire alarm system in both units to compensate for the lack of seperation beyond roof level. We have analysed ASET & RSET, reviewed travel distances and occupancy factors ensuring all exit widths etc are to the Scottish Technical Standards Non Domestic.

Firstly does this sound feasible to you?

Secondly do you know of any instances where this was achieved?

Many thanks

[CivvyFSO]

AFD does not really compensate for a lack of compartmentation.

[nearlythere]

My client has a 2000m2 retail unit in Scotlan which he wants to sub divide into 2 1000m2 units.
The existing unit is sandwiched between two other similar units with compartment walls beyond the roof covering.
The units are non sprinklered.

We want to provide a seperating wall to divide the units into seperate occupancies of medium fire duration (60 minutes) but for the seperating wall not to continue above the roof level. It will stop at the underside of the ceiling / roof with 1.5m either side of the wall being fire boarded with 60 minutes FR.

We propose to install an interlinked, monitored L2 fire alarm system in both units to compensate for the lack of seperation beyond roof level. We have analysed ASET & RSET, reviewed travel distances and occupancy factors ensuring all exit widths etc are to the Scottish Technical Standards Non Domestic.

Firstly does this sound feasible to you?

Secondly do you know of any instances where this was achieved?

Many thanks

What is the roof covering? Sandwich panel?

[GB]

The insulation from the sandwich panel is removed for a 3metre section and replaced with a known fire retardent insulating material, with 60 minute fire boarding fitted to the undersidet.

My understanding is that the objective of the functional standards of Scottish Building Regulations is for Life Safety purposes.
If the purpose of Separation is to limit the spread of fire and smoke within in this instance a retail unit, the provision of a L2 system within the unit where people will be awake at all times, should be sufficient for life safety.

We are not saying that there is no seperation, merely that the junction with the roof, the seperating wall between the two occupanices is not constructed as a compartment wall at the wall / ceiling junction and penetrating through the roof

[CivvyFSO]

If the purpose of Separation is to limit the spread of fire and smoke within in this instance a retail unit, the provision of a L2 system

....

.... does not do anything to limit the spread of fire and smoke... ?

[BCO]

Have a look at 2.1.15 of the technical standards. If the roof is non combustible it is permissible not to have the compartment wall penetrating the roof. If the insulation in the ‘protected zone’ 1.7m was ‘non combustible’ mineral wool for example then it would appear to meet the TS. I.e. no need to penetrate the roof.

[Phoenix]

BCO might have provided the answer here, I can't comment on that. 

But I would just support what Civvy is saying.  The requirement for compartmentation is a life safety issue but not in the way that you can compensate for by doing ASET v RSET comparisons or by installing better alarms.  Compartmentation is required not directly to protect means of escape but to limit the size of a possible fire.  The basic principle is that a smaller fire is a safer fire (and vice versa). 

If we allowed neighbouring premises to have no separating compartmentation then we could have some very large fires.  Now, the means of escape issues might be fine in all the buildings involved and everyone might get out safely but it is still not a safe situation (for a number of reasons) to allow such large fires to occur.

Also, neighbouring tenants have a right to expect reasonable protection of their business (not just life safety) against fire and smoke from their neighbour's premises.

Stu