A vapour control layer forms a barrier layer within buildings, which prevents interstitial condensation and thus simultaneously prevents problems from moisture and improves energy efficiency/comfort. It’s a vital component within the construction of buildings as water vapour can damage even the strongest building structures. A good vapour control layer helps to maintain the building quality and ensure effectiveness of insulation.Water in its gaseous state becomes water vapour which is totally invisible. This then diffuses through buildings from the warm interior of a household towards the cold exterior. As water vapour passes through the walls of buildings and meets a surface below the dew point (being when water vapour condenses), it becomes condensation which poses a threat to the effective of insulation and can damage building structures.

A vapour control layer, or vapour barrier, is installed in or along walls, ceilings, and floors on the warm side of the insulation to resists moisture from the warm side getting into the insulation. Any tiny amount of vapour within a wall cavity evaporates outside due to cooler external air, which makes it especially important that any paints or potential barriers are removed to allow this evaporation process to occur.

The Ultrablock reflective vapour barrier membranes have the exact opposite effect of the breather membranes. The Ultrablock 300 and Ultrablock 200 are both reflective and help with the thermal efficiency of the build.

When insulation is introduced within a building structure, a cold space between the insulation and outer building is created which generates a potential area in which this interstitial condensation can occur. It’s therefore important that this process is controlled, by preventing the movement of warm, moist air to the cold surface. A vapour control layer controls the amount of moisture allowed through, and thus the building structure can cope.

An air barrier prevents water vapour entering through air currents, such as individual holes within the building. Air flowing through holes like this are much more likely to transport water vapour through buildings than diffusion alone. A vapour barrier prevents water vapour movement through diffusion, which is the second most common way in which water vapour moves.

Vapour barriers are often specified in the construction of roofs to prevent moist air from the inside of buildings condensing and potentially damaging materials. A vapour barrier is an important way to preserve the effectiveness of insulation and therefore makes up a vital part of protecting the thermal efficiency of roof insulation. To be effective, this barrier must be warm enough to maintain temperature above the dew point which means sufficient insulation needs to be installed over the barrier. These barriers are especially important in commercial roofs as condensation penetrating roof materials can lead to considerable damage in the forms of both corrosion of materials and the growth of microorganisms.

All construction professionals should carefully consider the choices of vapour barriers prior to the beginning of construction works, as a well specified product will support energy efficiency and the lifeline of all materials. POWERLON® UltraBlock is a range of thermo-reflective air barriers and vapour control layers incorporating encapsulated aluminium foil or metallised barrier layers to maximise energy efficiency. The reflective foil surface improves the insulation characteristics of the installation, reflecting heat back into the building.

Characteristics:

• High water vapour resistance
• Range of membranes to cover all build types
• Reflective foil layer for enhanced retention of thermal energy
• Exceptional water vapour resistance
• Self-adhesive version available
• CE marking