Sealing with
a system

For secure connection joints.

Sealing connecting joints

Basics of sealing

The building structure connection joint has become increasingly important in recent years due to the more stringent EnEV requirements. It separates individual necessary building elements from each other or from the building structure. The joint must be sealed professionally and correctly in terms of building physics and meet the requirements of the ‘RAL guidelines for planning and installing windows and front doors for new builds and renovations’.

This illustrates the importance of the zone and emphasises once again that its sealing must be planned in advance in terms of building physics. The individual materials used for the various tasks must be coordinated with each other in terms of building physics. It is advantageous to install a vapour diffusion-tight layer or foil on the inside, which prevents moisture in vapour form from penetrating into the joint area and thus into the insulation material.

Window systems are installed in low-energy houses or even zero-energy houses in particular, which fulfil the highest requirements in terms of thermal and sound insulation and which must also meet the greatly increased criteria for burglary protection.

As the window elements bring ever greater savings in terms of sound and thermal insulation, the connection joint must also fulfil the required sound and thermal insulation requirements. In addition to the purely functional properties for sealing the building envelope, the products used to seal a building connection joint must increasingly fulfil special requirements in terms of sustainability, especially in new buildings.

Bild mit Darstellung über die Abdichtung von Anschlussfugen.

The connection joint must:

  • Equalise movements
  • Slow down the heat flow in the area of the joint
  • Slow down or prevent vapour diffusion from the inside
  • Prevent the ingress of moisture of any kind from the outside

Basically, the sealing of a building element is divided into 3 different levels (see image on the left). The outer sealing level must ensure impermeability to driving rain while at the same time being open to vapour diffusion.

The centre insulation level provides thermal and sound insulation in the structural connection joint. It must also compensate for movements of the building element, e.g. due to the opening and closing of a window or wind loads. The inner sealing level must ensure the airtightness and physical requirements (inside tighter than outside) of the building. It must also be ensured that a vapour barrier >40 m is installed in the interior at the same time as the joint seal. Of course, special construction-related solutions may require sealing modifications, but this is not the standard.

Bild mit Darstellung über die Aufgaben einer Abdichtung von Anschlussfugen.

Tasks of the sealing

Windows and front doors are building elements that have to fulfil a wide range of façade sealing requirements. In addition to the main function of opening and closing, these components have to fulfil special tasks, such as:

  • Thermal insulation
  • Sound insulation/noise protection
  • Weather protection, sealing against wind, air, driving rain, hail, snow, moisture, etc.
  • Burglary protection
  • Ventilation element
  • Barrier-free access to a building
  • Fire protection

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