Damming steel beams - does that have to be?

Again and again, the question arises whether steel beams, which are installed in the house, must also be thermally insulated. What this depends on, and when and how you should as possible insulate, you can read in detail in this post.

Steel beam as a heat conductor

Metal is basically an excellent conductor of heat. This means that a carrier that is "warm" should also be insulated as much as possible if it protrudes from an insulating layer or can get in contact with cold outside air (or leading out, colder components).

Otherwise, the steel support quickly cools down completely due to its good thermal conductivity at cold outside temperatures and thus represents a cold surface within an isolated area. This can lead to condensation forming on the steel beam.

Execution of the insulation

It is important that you always have to think of a vapor barrier in addition to the insulation. Insulation alone is usually not enough. Alternatively, the carrier can also be "wrapped up" in a diffusion-proof insulation solution - there are also many ready-made solutions on the market.


Individual steel girders should be decoupled as far as possible from a reinforced concrete floor. That is the only way to effectively isolate it.


So-called iso baskets are another way of insulating overhanging steel beams on existing steel structures. These are load-bearing connection elements, with which carriers can be connected to an existing construction. Their special design minimizes the otherwise occurring thermal bridge and eliminates it almost completely. This can be interesting in new buildings, for example, when it comes to the connection of balconies.

Insulation vs. Fire protection

In most cases, it is not only about the thermal insulation but also to look at the applicable fire protection regulations. In most cases, a steel girder has to be completely walled up anyway in order to comply with the applicable fire safety regulations. In this case, then the question of the insulation is unnecessary anyway.

Tips & Tricks

In the past, balconies were often not taken into account when expanding the insulation. This is a common building sin, which can often lead to the formation of condensation in components. This need not necessarily be the case, but if moisture problems occur in the corresponding adjacent wall component, it should be considered as possible insulation.

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