Fire door to a balcony access to flats

Does a door from a single staircase on to a second floor balcony providing access to three flats need to be a fire door, e.g. to an FD30 or FD30S standard?

The staircase only serves that floor, as the ground/first floor maisonettes are independently and externally accessible, and the building is of concrete construction.  The stair is considered 'sterile'.

The travel distance between the protected stair and the door to the furthest flat is 14m, and the window openings onto the balcony are at least 1.1m above the finished floor level.

Thanks