Thermal bridge caused by concrete columns on the extension

Hello friends and construction experts,

first of all, thank you very much for your help and the time you "waste" on me.

We started a new build in 2015, which has a small but annoying construction defect.

On the west side of our house, we built an extension (hallway extension). On this extension lies a filigree concrete slab (20cm thick). On top of it stand two concrete columns, which support a small dormer (see picture 1). The concrete columns are exactly vertical above the wall of the extension (meaning, they are not recessed on the balcony).

Now to the problem: Apparently, so much cold is conducted into the slab through the concrete columns that condensation forms in the corners of the extension (pictures 2-3). Elsewhere in the house, no condensation is found.

I have to say that the balcony has not yet been insulated and sealed from above. But I do not want to rely ONLY on that!

What can I do afterwards to minimize the damage!? Please help me get started!

THANK YOU!!!

Hi, I’m afraid insulating the balcony won’t do you any good. The columns cool down in the air and then happily conduct the cold into the concrete ceiling (thermally correct: they conduct the heat from the concrete ceiling to the surrounding air). If they are not somehow thermally decoupled from the ceiling, nothing will really change. That is a very bad thermal bridge.

Are they firmly connected to the ceiling (cast as a composite)? Or are they prefabricated elements that were simply placed on the ceiling?

Best regards,

Andreas

The columns are "just" placed on the ceiling. We drilled into the concrete ceiling and glued in the reinforcing bars. After that, we braided the reinforcement and poured the whole thing using cardboard tubes.

Then heating must be applied diligently from below so that the dew point is not fallen below.

Who planned that back then?

Layman's opinion: Get rid of the columns and redo it without thermal bridges.

First insulate the ceiling from above. The columns can also be additionally insulated a little afterwards. For this, for example, google "Säulenverkleidung aus Styropor". This can beautify a column and additionally insulate it a bit. With a capital, the transition to the concrete ceiling can be additionally insulated a bit more.