Providing fire resistant:

If the building does not provide everyone with alternative exit routes then it may be acceptable for people to pass the fire if they are separated from the fire by fire resisting construction.

It is common for buildings to be designed in a way that does not provide everyone in the building with an alternative exit to which they can turn.  Any multi-storey building that only has a single staircase is bound to have people on each storey who have no choice but to use the staircase to escape. They are, in effect, up a vertical dead-end.

This is why staircases are enclosed in fire resisting construction with self-closing fire doors between them and the rooms.  With the staircase effectively enclosed so that it remains unaffected by fire or smoke for an extended period (typically 30 minutes) people will be able to easily pass down a staircase whilst a fire is in a room on the other side of the fire resisting construction and fire door.

When a protected escape route is created by enclosing it in fire resisting construction it is  important  that  the escape route does not  contain  anything  that  may catch  fire because if it did and those items did catch fire then people may not be able to pass the fire to get to safety.