Best Practice Approach - Intelligent Vapour Control Layers

An increasing number of experienced contractors are switching to a new best practice approach incorporating intelligent vapour control layers as a standard to protect buildings from structural damage.

What makes these vapour control layers (VCLs) intelligent is that they adapt to changes in humidity conditions. These highly advanced building materials have been created to provide variable permeability. Essentially, that means that the VCLs change their permeability, becoming more vapour resistant during winter and more vapour permeable in the summer.

Variable permeable membranes help regulate the natural moisture-loading and drying out cycle of the building envelope by protecting the building fabric in the colder, wetter months and allowing it to dry out effectively in warmer, drier months.

Product Information

The industries growing understanding of the complexities of Heat, Air and Moisture Movement (HAMM) through the building envelope has led to a shift in the industry in two ways. First, modelling software like WUFI® provides hygrothermal assessment and better models the condensation risks. Second, a new generation of advanced construction materials is now available to support the long-term health and durability of a building.

Construction professionals in the UK will be familiar with BS5250:2021 ’ Management of Moisture in Buildings – Code of Practice’ as the authoritative resource on this topic. The Standard specifies the need to be aware of both the internal and external factors contributing to condensation control and building health, where it states: “In order to avoid the occurrence of excess condensation, which can result in mould growth and damage to the building fabric, designers should assess the amount of water vapour likely to be generated within the building … and consider the effects of the external climate.”