What is the open space between the ceiling of the top floor and the underside of the roof in a building known as?

The space between the ceiling of the top floor and the underside of the roof is referred to as a cockloft. This area is typically found in buildings with flat roofs or those that have a sloped roof configuration. The cockloft can contain structural elements, insulation, and sometimes wiring or ductwork.

Its significance in fire safety is considerable. A cockloft can allow fire to spread quickly between floors, particularly in buildings where ventilated spaces are connected. Firefighters must be aware of this space during firefighting operations, as it can represent a hidden fire hazard and complicate rescue efforts.

The other terms mentioned refer to different types of spaces: an attic generally refers to any open space under the roof, often with a sloped ceiling, while a loft usually describes a living space or storage area created in an upper level of a building, often used in homes or industrial settings. The truss area refers to the space occupied by roof trusses, focusing on the structural framework rather than the open space itself. Thus, while these terms relate to upper areas of a building, the specific term for the space in question is the cockloft.