Technical Booklet E Fire Safety·Page 42·2.20
Doors in existing stairway enclosure
Doorways in the stairway enclosure must be imperforate (solid), and doors to habitable rooms or kitchens must be self-closing; new doors to existing habitable rooms or kitchens must be fire doors.
Other than where paragraph 2.18 requires a fire door, every doorway in the enclosure to the existing stairway should be fitted with an imperforate door. A door to a habitable room or a kitchen should be fitted with a self-closing device.
Where a new door is to be provided to an existing habitable room or kitchen it should be a fire door.
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