Stairways, if unprotected from fire, can rapidly
become affected by heat and smoke, cutting
off the escape route and allowing fire spread
to other floors. However, if adequately
protected, escape stairways can be regarded
as places of reasonable safety to enable
people to escape to a place of total safety.
In most premises designed and built to building
regulations and served by more than one
stairway, it is probable that these stairways
will be protected by fire-resisting construction
and will lead to a final exit. If any floor has
an occupancy of over 60, each storey should
have at least two exits, i.e. protected routes.
The figure of 60 can be varied in proportion
to the risk, lower risk slight increase, higher
risk lower numbers of persons.
It is possible that you may have some stairways
which have no fire protection to them. In this
case they are not designed for escape and are
normally known as accommodation stairways
(see accommodation stairways on page 84).
If you have a protected stairway(s) then it
is essential that you maintain that level of
fire protection.