VARIO – the intelligent vapour retardant

The innovative VARIO system intelligently adapts to the ambient temperature and humidity. VARIO climate membranes block moisture that diffuses into the structure from inside the building in winter, allowing the trapped moisture to diffuse harmlessly into the building interior in summer.

During summer, the climate membranes allow 25 times more moisture to escape from the building structure, than penetrates into it during winter. So with VARIO as a vapour retardant, the construction dries out effectively and moisture-related damage is avoided.

This unique effect is, of course, subject to careful workmanship.

Vapour retardant: Moisture is blocked in winter.
Moisture can escape in summer
VARIO climate membranes: Unique intelligent vapour retardant with variable diffusion resistance sd.


At the relatively low humidity levels present during colder months of the year, the so-called diffusion resistance of the VARIO membrane is increased, i.e. the molecules close up and stop the diffusion of water vapour, thereby working as an effective water vapour retardant. This prevents moisture in the room from penetrating into the structure.


With high humidity and temperature during the summer months, the diffusion resistance of the VARIO membrane is reduced, i.e. the molecules move apart, and allow trapped moisture to pass through the membrane into the room. Moisture that had penetrated the structure can now escape.

VARIO – unique variable diffusion resistance

Only VARIO intelligently adapts to the prevailing climatic conditions, preventing moisture from penetrating into the building structure and allowing trapped moisture to diffuse into the room. Conventional water vapour retardant membranes have a diffusion resistance that remains static, regardless of climatic conditions, and function only as a water vapour stop. Moisture that has become trapped in the building structure cannot escape, which can lead to damage.

Careful workmanship

The VARIO effect is subject to careful and effective bonding of overlapping seams in the membrane and sealing of junctions with components and around all penetrations, such as chimneys, pipes and services, with appropriate VARIO System products.