Page 7 - food store model (with basement accomodation)

Reference Guide Fire Strategy

levels, and particular consideration should be given to coverage in basement spaces that are

infrequently accessed.

1.5.2 Occupancy Numbers

The methodology used to determine the anticipated population within a given space is the
use of plan floor area and a floor space factor. The determination of a projected occupancy

is critical in establishing the number of escape routes required, the sizing of doors on escape
routes and the necessary width of stairs.

To determine population numbers; divide the plan floor area by the appropriate floor space

factor given in the table below. A value of 4.0m2/person has been adopted for a shop sales
floor, in accordance with information provided by Co-op and taking account of the

recommendations of ADB Table C1. This value is further in accordance with Table 9 of
BS9999:2017.

Usage Floor Space Factor (m2/person)

Shop sales area 4.0

Office 6.0

Storage and Warehousing 30.0

Where a given population is known, for example number of staff likely to be present at any

one time, this value may be taken in lieu of an occupancy calculation undertaken. For
example, a store with 400m2 of free shop sales area may be allocated a population of 100
persons (400/4.0) plus a notional allowance of 5 members of staff.

1.5.3 Fire Exits

Where the anticipated population of a building, or part thereof, is >60 persons, ADB requires
that an alternative escape route is provided. Where two distinct exits are provided, it is
reasonable to assume that one of these may become unusable in the event of a fire, and it

follows that each individual exit should have sufficient capacity to accommodate the
population of the entire floorplate.

Document Classification Final Document Ref: 3.1-RCS-RHSE-(110)-263 Version 1.1
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