Vapour control by STEICO
STEICO vapour control layers can play a vital role in maintaining the integrity of the overall building fabric by limiting the amount of moisture which can enter the building fabric. A vapour control layer, that passively manages moisture, is important for structural stability and the building’s ongoing healthy operation and in conjunction with diffusion open external layers and breather membranes ensures a long-term robust management of moisture risk within the structure.
Controlling the level of moisture within a building is one of the most important parts of construction. Get it right and you can positively impact the building’s longevity and energy efficiency in operation, and help to reduce relative humidity , which has a direct impact on the quality of air that we breathe. Get it wrong and the building can begin to fail before it should due to condensation, damp and mould growth that might cause structural and health problems.
Vapour control layers should be installed on the warm side of the insulation in walls, roofs and floors. Doing so helps keep the insulation dry by allowing the passage of air while controlling the flow of warm water vapour, so it doesn’t rapidly encounter a cool surface. That helps prevent interstitial condensation and maintains the building’s thermal envelope. Controlling the flow of air rather than eliminating it helps keep the building energy efficient.
Why is permeability important with a vapour control layer?
It might seemingly make sense to want an impermeable layer to stop water entering a building entirely, but that doesn’t consider the water that needs to escape the building. The people who occupy the building will produce water vapour in their day-to-day lives through breathing and other normal activities such as cooking, showering etc.
Incorporating membranes that allow a controlled migration of moisture through the building fabric can reduce the reliance on mechanical ventilation systems. An excess of warm, damp air in a house can lead to a range of problems, including:
- Mould – Damages buildings through decay and releases spores which can compromise air quality and harm the occupants through allergic reactions, respiratory issues and more.
- Condensation – Can damage the structure of a building, particularly timber elements which can rot and weaken. Metal elements of a building can rust or corrode, affecting the structural integrity of the building.
How could a vapour control layer affect the sustainability of a building?
Controlling the movement of moisture through a building with a vapour control layer can affect the overall sustainability of the building:
- Energy efficiency – Warm, moist air takes longer to heat in the winter and longer to cool in the summer. That can make your house less energy efficient and lead to higher carbon emissions through excess heating and cooling requirements through the year.
- Thermal efficiency – A vapour control layer can also contribute to your insulation system by keeping it as dry as possible. Similar to your house as a whole, wet insulation is unlikely to perform as it should, leading to increased energy usage and carbon emissions in most cases.
- Airtightness – If you are controlling the flow of air in and out of the building, you are also limiting the uncontrolled flow (or leakage) of air in places where you don’t want it to leave. Greater airtightness is important for eliminating draughts and other leaks which can affect the building’s thermal performance.
How is a vapour control layer installed?
When you install the vapour control layer it should be taped and sealed at all joints and connections to adjoining materials with the range of tapes and sealants from the STEICOmulti range.
All our sealant products are solvent-free and suitable for different jobs. For example, a tape is used to seal sheets of vapour control membrane together in a way which doesn’t leave gaps for moisture to exploit. The right tape or sealant can therefore help to ensure that your buildings vapour control strategy performs as intended.