BS5588:Part 10 - Separation between shop and mall for 2 level units

[Jon Barrett]

BS5588:Part 10 states that 'Compartmentation should be provided between the mall and any upper storey of a unit which has open connections with a lower storey in that unit which also has access from the mall'.

The reason for this is given in the commentary to this clause as... 'In order to reduce the possibility of a fire in one unit
spreading uncontrolled throughout the complex'.

In the case of units that fall under this requirement there is no limiting size, unlike the two other requirements under this clause i.e. '1) any units with a floor area exceeding 3 700 m2 at that level; 2) opposing units, where each has a floor area exceeding 2 000 m2 at that level.'

Does anyone have any experience of this requirement being avoided on the basis of shop unit size, or have any information on whether this requirement is now no longer applied?

Thanks,

Jon

[wee brian]

The big problem with two storey units (as I recall) is that the smoke from a fire in the unit may enter the mall at both levels.

Twice the entrainement (not to mention any caused by spill plumes in the unit) twice the smoke to control in the mall.

[Jon Barrett]

You're right. Avoiding smoke discharge from two levels would have to be achieved but this could be done with smoke curtains - but this wouldn't satisfy the requirement for compartmentation. As I understand it the requirement for compartmentation is a belt and braces requirement so that in case the sprinklers fail then a large fire would be prevented from spreading to other units.

The issue I have is that an MSU (with a total floor area across the two floor levels of around 1800m2) that is providing it's own smoke extract currently has the requirement to be fire separated from the mall at the upper level - which would mean quite a length of wall/glazing needing to be 2 hour rated. I have suggested that if they separated the two floors with a fire shutter over the escalators this would also satisfy the requirement.

I may have to look at this from a fire engineering point of view i.e. if the whole shop went up (only if the sprinklers failed) then would there be fire spread to adjacent units via radiation.

[wee brian]

Theres no real fire safety reason for this I wouldn't get too excited about it.

If they really have to have compartmentation then you can run a wall behind the shopfront. That way you can do it with plasterboard rather than FR glass.

[Jon Barrett]

I'm not the one getting excited about it! It's building control who are insisting on it because it's in BS5588:Part 10 and it is not covered in the contracts that have been appointed!

I'll wait and see whether the MSU resists the fire shutter over the escalator, if they do then I may have to look at the potential fire spread risk.

Thanks.