What is a thermal bridge and why is it dangerous?

A Thermal Bridge is an area of ​​your home where heat is lost much faster than with unproblematic parts. Put more simply, on thermal bridges, your money flies figuratively out of the window.

Thermal bridges are also colloquially referred to as cold bridges . This is not physically correct. In the immediate vicinity of the thermal bridge lower temperatures result on the inside of the affected component, as it is the case in the rest of the room. This causes higher energy consumption, as well as problems with moisture in and on the components due to condensation. It can even lead to mold growth and damage the building fabric sustainably.

Thermal bridges occur especially at transitions between two components. However, there are different ways to keep in mind. Structurally conditioned thermal bridges, geometry-induced thermal bridges and thermal bridges due to improper construction.

Especially the latter can be avoided well. A poorly executed insulation, which has small gaps between the insulation boards, is such a possible thermal bridge. Geometric bridges, on the other hand, are often difficult to avoid (for example, in the corners of two outer walls).

There are some points in the house that are particularly vulnerable and should be carefully considered. Particularly noteworthy here are:

Ceiling connections in the base area

In the area of ​​house bases, it is often impossible to consistently insulate them. Heat can be lost via the ceiling connection in the base area and then to the outside. If the basement is not insulated from the outside, it may be necessary to insulate the floor slab. Ideally, however, the insulation should be planned down to the ground (Caution: Use moisture-proof insulation).


Balconies are often designed as cantilevered components. This means that the floor slab goes through to the outside. To avoid a thermal bridge here, one would have to contain the entire balcony ceiling. It makes more sense to plan balconies over columns in such a way that they carry themselves. So the insulation of the outer wall can go through. Another option is so-called iso-baskets. These make it possible to hang the balcony slabs on the facade .

House corners

As already mentioned, the corners of the house are often problematic. Here, the dew point can be quickly fallen below and there is water in the components. The geometry of a corner is simply responsible and you can basically do little at first. There are in a corner nunmal more outer surface than inner surface. In order to create as few heat bridges as possible through corners of the house, it is advisable to plan as few room corners as possible.


The attic is the walling at the upper end of the outer wall and is mainly used for flat roofs. An attic should be kept to a height of at least 50 cm, ideally it will be completely packed. This way, thermal bridges can also be avoided.


There are many dangers to the development of thermal bridges in the windows. You should make sure that the window reveal is well insulated. Insulation must also be considered at the connection points of a windowsill. In addition, shutter boxes are popular thermal bridges. Ideally, these should be completely equipped with thin, particularly good insulation from the inside. Vacuum insulation panels are ideal here. These hardly allow heat to pass through but are very thin.

There is a great danger if the thermal bridge causes mold fungi. These are difficult to remove completely. However, this is necessary to make sure they will not come back. A superficial killing of mushrooms is not enough here. Many home remedies only bleach the mushrooms. In addition, killed molds can still cause allergic reactions.

With smooth surfaces you can easily remove the mold with normal cleaners. For wood, upholstery or porous materials, however, it is much more difficult. Even wallpapers are affected. For example, these must be disposed of completely. Even plasterboard must be completely removed in case of infestation. This can be very time-consuming.

Often, only a hammer and a chisel help with infestation. Therefore, you should not let it come so far. When building a house, make sure that thermal bridges can not arise. With modern insulation this is no problem.

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