Ventilated roofs waterproof coating, responsible for protection against precipitation is separated from the thermal insulation by a ventilated air gap. This design completely eliminates the problems associated with the uncontrolled flow of moisture from the side of the heated interior. Warm moist air, which from the inside of the house penetrates through thermal insulation into the roof space, it is easily removed from the outside through the ventilation holes. Even if there is condensation of water vapour on the bottom of the structure supporting the watertight coating and – dripping – dampness of thermal insulation, it's enough a few warmer days, so that thanks to proper ventilation, this moisture evaporates.

Ventilated airspace can vary in height – this distinguishes the tubular roofs from each other, Slot, bipartite and bi-division-passage.

The movement of air in the ventilated gap causes a temperature difference and wind action. The temperature difference between the air in the gap and the outside air causes the convective movement of the air. However, if the height of the gap is small or the airflow is hindered by the elements of the roof structure, this thermal forcing will not cause sufficient water vapour to remove the ventilation exchange. It becomes necessary to force the movement of air by the action of the wind. So that regardless of the wind direction, there is always a pressure difference caused by the pressure of the wind on the building – ventilation holes are placed on all walls of the roof. This is called. multi-axis ventilation of the roof. Air exchange in the roof gap will take place not only along e.g.. structural beams or in the vicinity of openings.