(1) The width of an exit-way or the aggregate width of exit-ways serving any building or portion of a building shall be not less than a width calculated in accordance with the following formula—

W(width) = N × 275 millimetres (width-unit)
Where N = the width-number (number of width -units) found from the equation
N=P/E
Where P = the population served by the exit-way or exit-ways concerned at the point or points at which the widths are being considered
E= the maximum number of persons per width-unit of exit-way set out in Table XIV
N shall be calculated to the nearest whole number, fractions less than one-half being disregarded:

Provided that, in any event, the width of any exit-way shall be not less than 1,1 metres, except that—

a) In any building having a population not exceeding 25; and

b) In any building not exceeding two storeys in height having a low fire-load and a population not exceeding 40;

The minimum width shall be 900 millimetres for a stairway and 800 millimetres for other components of the exit-way.

TABLE XIV
NUMBER OF PERSONS PER WIDTH-UNIT OF EXIT-WAY

(2) The width of an exit-way shall be measured as the clear unobstructed width.