Thermal bridge/cold bridge? Concrete slab vs surface temperature.

Good day. I am interested in the topic of thermal bridges or cold bridges (are they the same?). I once measured the surface temperature of the walls and ceilings in my apartment (Kfw 70, Poroton, 4 years old). I noticed that a ceiling in the study shows different surface temperatures. This ceiling is located on the upper floor, and above it in the attic floor is 50% living space (so heated) and 50% unheated (roof terrace, 50% covered). The surface temperature of the ceiling in the heated area is about 21 degrees warm. In the unheated area (where the roof terrace is above), the surface temperature of my ceiling is only just under 17 degrees warm. Measured now at about 0 degrees outside temperature and a heated apartment. Also, the exterior walls of my apartment below the roof terrace are "colder" compared to the exterior walls below heated rooms of neighboring apartments.

My question: Do these temperature differences indicate thermal/cold bridges, and could they cause long-term problems with mold, etc.? PS: Of course, an expert could clarify this question for me through various measurement methods. But I would first like to get some tips and advice here. Or is it quite normal that a ceiling—which is below a roof terrace (50% covered)—is naturally colder than a ceiling below a heated room. That would be understandable. But the transition of the ceiling from warm to about 4 degrees colder toward the exterior wall concerns me a bit and interests me.

Thank you very much.

That is completely normal, because transmission heat losses depend on the temperature difference between inside/outside (1st law of thermodynamics). Therefore, these losses are logically higher in the area where the roof terrace is than where there is another floor with additional energy input.

As long as you heat and ventilate accordingly, you have nothing to fear. (Unless there are construction defects). To be absolutely sure, you can have a thermography done but by someone who knows what they are doing and not just someone who bought a thermal imaging camera at an auction.

A window also releases more energy to the outside than the adjacent wall.

That is quite normal, because the transmission heat losses depend on the temperature difference between inside/outside (1st law of thermodynamics). Therefore, these losses are logically higher in the area where the roof terrace is than where there is another floor with additional energy input. As long as you heat and ventilate accordingly, you have nothing to fear. (Unless there are construction defects). To be completely sure, you can have a thermography done, but by someone who knows what they are doing and not just someone who bought a thermal imaging camera at an auction house. A window also releases more energy to the outside than the adjacent wall.

Good day. So it is quite normal (which is also logical) that the ceiling below an unheated room or open roof terrace simply has to be colder by nature. Despite sealing, etc. The colder wall or ceiling then does not tend to mold formation if part of the ceiling and wall is colder than the other part of the ceiling/wall in the same room. Proper ventilation and heating is, however, a prerequisite for this.

Yes, that's exactly how it is.

Yes, that's exactly how it is.

Hello. Can you say at what temperature problems are to be expected? There is the dew point where cool components start to sweat, right? For example, if room temperature is x degrees, humidity y, and outside temperature is z value? Then the ceiling or wall must not be colder than xy? Are there data available here? Thank you

Yes, dew point indeed. But it is variable. Tables and calculators are quite easy to find.