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A new vapour barrier membrane by Walki for healthy buildings

A report by the World Health Organization (WHO) states that 75-80% of all problems with building constructions are caused by moisture. Trapped moisture, either due to external intrusion or condensation from within, causes dampness, which further damages structures.

Walki’s unique solution, Walki®Active, is the answer to this problem. It’s a dual-purpose, vapour variable membrane made from PP non-woven and a functional film layer.

In many countries, plastic films or other tight insulation vapour barriers are often used as moisture barriers. This triggers moisture challenges. Designed to adapt to the environmental and climatic changes, Walki®Active’s key feature is its variable water vapour barrier property.  

"When the air humidity is low, the vapour barrier property of our laminate is high, and when the humidity is high, the barrier is low," explains Sipi Savolainen, Technical Service & Development Manager for Construction at Walki. So during winter, when it is warmer indoors than outdoors, vapour tends to flow from inside to outside but the functional film layer acts as a vapour barrier. This ensures that virtually no vapour can flow into the structure during cold weather. During summer, on the other hand, the polyethylene-copolymer film opens to allow water vapour to flow from outside to inside.

"By using this membrane, we can ensure moisture does not condense in the insulation layers inside the buildings," Savolainen points out.

From idea to product
The development process of Walki®Active showcases Walki’s innovation spirit. Several factors had to be considered in the process.

"We had to map the polymers that would fulfil the water vapour barrier requirements, find suitable polymer structures that will enable us to produce the product, and make minor adjustments to our machinery to make it suitable for production," lists Savolainen.  

Walki®Active is also listed into WUFI, software products that allow realistic calculation of two-dimensional heat and moisture transport in walls and other multi-layer building components exposed to natural weather. This makes it possible for construction engineers to simulate the behaviour of their final wall structure before getting started with construction.
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DETAIL 1-2/2022

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