Solving the problem of reliably achieving airtightness in buildings, with a robust solution and great benefits!
Up to half of all heat loss in buildings can be due to uncontrolled ventilation and air leakage through the external fabric of the building envelope. Warm air can still leak out and cold air can still enter through the joints of the building fabric, despite increased insulation values. A well installed airtightness system can reduce air leakage in the building. The main air leakage points that attention should be paid to are:
- Joints between walls, roofs and ceilings
- Joints between foundation and wood structure in timberframe
- Overlaps and interruption of membranes
- Joints between walls and window/door frames
- Penetrations in the external envelope – pipes, cables etc.
- Unplastered blockwork, such as between intermediate timber floor joists
Due to air leakage, an average house needs to heat up to 4-5 times more air than is actually required to reach a comfortable living temperature. Proper insulation and an airtightness system reduces this heated air loss, saving energy and reducing heating bills.
Moisture in buildings arises from several sources: if it is not properly controlled it can lead to mould growth and condensation. There are well documented risks associated with the presence of mould in buildings. Fresh, clean air is always highly desirable. Condensation, if unchecked, can lead to damp and mould forming which can have an adverse affect on both the building’s and the occupants health. By following good “fabric first principles” and installing an airtightness system that minimises condensation risk, it will ensure there is no structural damage from moisture, mould and damp.
Heat that escapes from buildings carry a significant amount of moisture. As this warm, vapour-laden, air passes through insulation and can leave behind humidity, which will weaken the u-value or thermal performance of the insulation. If this moisture cannot dry out quickly, it could lead to further damage in the fabric of the building. By installing an airtight vapour layer, it protects the insulation, thus enhancing the thermal performance of the building.
As we build more airtight and thermally efficient buildings, the need for proper ventilation increases. A ventilation system can range from simple natural ventilation, right up to mechanical systems for low energy/passive standard house design. If a mechanical ventilation system is installed, the building must be particularly airtight in order for that system to work efficiently, and to enjoy healthy, comfortable buildings.
Houses are well insulated now, under building regulations, and must meet minimum U-value calculations. However, a badly fitted airtight layer, or unrepaired damage to the airtight layer will reduce the U-value calculation. On the other hand, a well installed airtightness system will ensure that the desired U-value is attained, and will lead to optimum building results for the lifetime of the Building Energy Rating.
The weak points of a building are not large surfaces but all the interruptions and openings in the roof or wall, such as conduits, waste and soil pipes and ducts, pipes for solar systems, window and door frames. The key is to totally seal these air leakage points. The Synergie Airtightness system can ensure this happens. Etag supply Synergie – a complete system including an airtight vapour control layer membrane and airtight tapes for achieving optimum airtightness.
The Synergie Sd2 vapour control layer is a two-layer, translucent airtight vapour control layer with an Sd value of 2m and is 100gramme/m2 in weight. It is manufactured as a combination of an upper protective layer of water-repellent, UV-stabilised, completely 100% airtight, polypropylene spunbound fleece and on the underside, the functional film, slightly diffusible (allowing slow vapour diffusion) polypropylene film. With its optimum fixed Sd value, Sd2m, this fully 100% airtight VCL is perfectly suitable for the underside of ceilings in most pitched roof applications.