Subsection B9 – Exits at Ground StoreyClause B9.1The enclosing walls of every required staircase should be so continued at ground storey as to separate from the remainder of the building any passage or corridor leading from the required staircase to its ground storey discharge point. Every opening from the ground storey to such passage or corridor should be separated from it by a protected lobby; provided that:(a) in the case of a building served by two or more required staircases, a cloakroom, lavatory, water-closet, caretaker’s office, fire control room or caretaker’s counter may open off such passageway; and(b) in the case of a building served by three or more required staircases, one in every three such required staircase may discharge through fire rated doors to an entrance hall and that part of the entrance hall which forms the exit route should comply with the requirements of Subsection B5.Clause B9.2Where an exit route from a ground storey also forms part of the exit route from a required staircase, the width of such exit route should be not less than the sum of:(a) half the width required for the exit route from the ground storey;(b) the width required for the required staircase from the upper storeys; and(c) the width required for the required staircase, if any, from the basements.Subsection B10 – Access to Required Staircase(s) within a BuildingClause B10.1In case of a building with one required staircase, attention is drawn to the requirements in Subsection B6.Clause B10.2In the case of a building with two or more required staircases, the access to the required staircases should be so arranged that:(a) each required staircase is approached from a different direction provided that deadends are permitted, in accordance with Clause B11.2; and(b) the door of one required staircase, or the nearest point in the perimeter of the landing to the required staircase where there is no door, should not be nearer than 6m from the door or a similar point of any other required staircase measured in a straight line along the wall. See Diagram B2.