Capacity of Roof Terrace for 6 storey building with one means of escape

[HassanA]

Hi All,

I've picked up a small project where we are being asked to confirm the capacity of an existing roof terrace of a 6 storey office building.

The building is a smidge under 18M high, roof terrace is approx. 175 Sq. M. Single means of escape via external staircase with a clear width of 1000mm between handrails. Max travel distance is 18M. Use of building is Offices. The means of escape is 1 way i.e. it's only used for egress.

I've tried reviewing the previous Architect's information and can't find an answer to their designed capacity and of course our usual independent approve inspector is rightly suggesting that the building tenant produces a Fire Risk Assessment.

Attached is part of the roof plan. Red is the roof terrace that they want to know how many people can occupy the space. Yellow are the escape stairs - again, escape stairs are external with no covering etc.

Am I right in thinking that the Approved Documents aren't useful here as the building in question has already been built (building was completed circa 2017/2018).

Thanks in advance.

h.

[AnthonyB]

It's only a single escape so would have to be limited to 60 regardless of how big the terrace is.

If due to usage it could be classed as a storey as it's over 11m it should usually have access to 2 stairs anyway.

These principles pre date the date of build and still apply now