Glossary

Vapour barriers are membranes made from various materials that are installed on the insulation layer of a building. They prevent moisture from penetrating insulated parts of the building and thus prevent mould from forming.

A vapour barrier is a continuous, flat layer with a defined water vapour diffusion resistance, which reduces the diffusion of water vapour from the air into a building component.

The term ‘breathable’ refers to a material’s ability to allow water vapour to pass through whilst remaining impermeable to liquid water. This property is also well known in the context of ‘functional clothing’.