Diagonal vapour pressure ventilation

Cellars, crawling spaces and closed foundations often suffer from excessive moisture which could lead to serious problems. 

Cellers, crawling spaces and closed foundations are often exposed to moisture accumulation, especially because of the vapour permeability, ground water pressure and lateral infiltration. These spaces are inclined to function as closed “bell jars”, which means that moist air and vapour barely have the possibility to escape. This creates a higher vapour pressure inside, which could lead to moisture problems, mould, wood rot or damage to the structure.

To control this problem naturally, we advise the use of diagonal vapour pressure ventilations. This system uses small ventilation pipes, strategically placed around the outside perimeter of the cellar or crawling space. The offer a constant, passive airflow which carries the moisture and moist air outside.

Technical specifications:

• Diameter of the ventilations: 5 cm
• Placing distance: Every 2 meters around the entire outer perimeter.
• Height above ground level zone: 5 to 10 cm
• Positioning: The ventilations are placed diagonally, which provides an optimal air circulation and a natural, vapour pressure moving moisture transfer.

How do they work?

The vapour pressure ventilations use the natural difference in vapour pressure and temperature between inside and outside. In summer, when the air outside is warmer, the air rises through the ventilation openings to the outside. In winter, when the outside air is colder and drier, the larger vapour pressure difference ensures a movement of moisture from the inside to the outside. This prevents and oversaturation of moisture in the cellar or crawling space.

Because the ventilations are placed diagonally, a better circulation occurs than with straight placed ventilation systems. The air flows not only along the walls but also through the space itself, which makes the air renewal and moisture transfer more efficient.

By using natural vapour pressure ventilations, the problems are prevented without the need of mechanical ventilation systems. This ensures it a cost effective and durable solution for moisture control in subterranean construction.

An important aspect of the system is that the vapour pressure ventilations are placed  around the entire outer perimeter of the cellar and crawling space. This guarantees an even airflow through the entire space. Every 2 metres a ventilation pipe is places or drilled, which is sufficient to maintain a constant air circulation and effectively remove moisture.

Deviations for residential cellars or semi-basements

Although the vapour pressure ventilations are ideal for non-inhabited spaces like cellars, crawling spaces and closes foundations, this does not apply to residential cellars or semi-basements. In these living spaces the continuous ventilation through vapour pressure ventilation can be too intense, which could lead to a draft or an uncomfortable inside climate.

In residential cellars and semi-basements technical ventilation systems with heat recovery are more apt, because they provide a controlled ventilation with a constant humidity and temperature. Moreover, insulation and vapour barriers to prevent moisture problems have to be taken into account when designing residential cellars of semi-basements.