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Window wall connection

The window wall connection - the nuts and bolts for good energy efficiency

From an energetic point of view, each window represents a weak point in the thermal insulation of a house. This is not only the case because the glass is a material that has a higher heat transfer value than a brick wall, or because the frame of the window is in one is constructed in a certain way. Rather, it is the transition from one component to another - from the wall to the window - that can be a problem from a building physics point of view.

This component transition is a classic point at which thermal bridges can occur, because more energy is lost from the inside to the outside at the joint of the wall connection than via the tightly closing window or wall. In the case of poorly installed windows, condensation and, in the worst case, mold can form at precisely this point. However, the modern construction industry has developed measures to prevent precisely this.

However, a good wall connection does not only have an energetic aspect, it also affects all functions that the window should perform. Here are the aspects again at a glance:

  • A correctly executed wall connection keeps the heat in the house and only a little energy is lost to the outside.
  • Fixed anchoring is important to ensure protection against burglary.
  • The sound insulation can only be fully effective if the connection joint is also well executed.
  • The correct and professional wall connection is an important criterion for the intrinsic value of the component.

So-called masonry anchors are used to anchor the window in the wall opening. After aligning the frame, the holes for these anchors are pre-drilled in the sides of the frame with a drill press. Then use a long drill to make the hole for the masonry anchor through the frame in the window reveal.

With knock-in dowels that are guided through the hole, it is then easy to anchor the frame firmly in the window reveal. This procedure ensures that the hole is placed in the right place in the window reveal and that the aligned and temporarily fastened frame cannot slip again.

Airtight design of the wall connection

While the firm anchoring of the frame in the masonry has always been an important criterion when installing windows, the airtightness of the wall connection has recently come more into focus. In the past, the gap between the window and the wall was simply filled with foam and then plastered. This makes a very tight impression, but modern insulation standards have shown that such a structure is not completely airtight.

This means that energy can be lost through this weak point, especially in windy weather. The air flowing past the window element on the outside creates a suction effect that practically pulls the energy out of the interior - only to a comparatively small extent, but continuously.

The solution to this problem is simple: the wall connection also needs its own seal. Special sealing tapes are now available on the market, the edge of which is glued around the frame before assembly. If the frame is then inserted into the wall opening, the sealing tape is placed over the joint.

Of course, the joint is still filled with foam and plastered, but the sealing tape ensures that it is airtight and that a high level of energy efficiency is achieved. This type of installation is the technical standard that should be implemented in a new building. But it is also useful in an old building.

Tip: The airtight installation of the windows is called RAL installation in technical terms. The reason for this name is that this technical standard was the basis for the introduction of the RAL quality mark for windows + assembly.

Integration into the thermal insulation composite system

In order to meet all the requirements for optimal thermal insulation, the joint from the wall to the window must not only be airtight, but also be integrated into the thermal insulation. In the case of a thermal insulation composite system, the window reveal should be insulated so that the insulation material covers the installation joint of the wall connection by at least three centimeters.

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Tags:Installation, window