July 13th, 2016

Vapour Control Layers

What is a vapour control layer (VCL)?

A vapour control layer helps you protect your building from the consequences of condensation. Condensation is formed when warm moist air rises and condenses into a liquid on contact with the colder surfaces above the insulation. The idea behind a vapour control layer is to install it on the room side of the insulation so it blocks the passage of warm moist air entering the structure.

Why is a VCL important?

A VCL is a vitally important component in your build up acting as one of the protective layers that minimises the amount of warm moist air that enters a construction element. A VCL in conjunction with the correct use of ventilation and membranes will effectively eliminate the risk of interstitial condensation. It’s the two design principles working together that minimise the damaging effects of condensation on the structure.

A VCL prevents damp and mould which in turn, prevents major respiratory problems, according to the NHS. As well as significant health implications, condensation can also cause structural problems, weakening timber framed buildings and corroding other materials. Another significant advantage of the VCL is that it will prevent installed insulation getting damp and losing it’s thermal properties.

What is the difference between a vapour control layer and a breather membrane?

Vapour control layers are positioned to the inside of the insulation in order to minimise the amount of warm moist air entering the construction. Breather membranes are positioned to the outside of the insulation acting as a weather barrier while still allowing moisture particles to escape from the inside.


We stock two of the market leaders in VCLs – The SIGA Majpell and the DuPont AirGuard Reflective. Both are available in 1.5 x 50 m.

The SIGA Majpell is available from £129.03 incl. VAT  + delivery and the DuPont AirGuard Reflective is available from £86.40 incl VAT + delivery.

We can ship our VCLs to anywhere in Ireland and the UK so please contact us directly for the most competitive prices

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