Basements, escape and protection
In all buildings with basements (other than
very small basements), stairways serving upper
floors should preferably not extend to the
basement and in any case should not do so
where they are the only stairway serving the
upper floors. Any stairway that extends from
the basement to the upper floors should be
separated at basement level by a fire-resisting
lobby or corridor between the basement and
the stairway. All basements used by more than
60 people, or where there are no exits directly
to a place of total safety, should have at least
two protected escape stairways.