Moisture/water stains in the basement after the heating program

Hello everyone,

we have now completed the screed heating protocol and according to the tiler, the screed is well dried.

However, during the heating phase, water stains appeared on the walls in two larger rooms (only in the basement) (see photos).

Our site manager now suggests setting up drying equipment. Is this the right approach? I would also be interested to know why the stains appeared at all (only in the basement, not on the ground floor and upper floor). Was it due to incorrect execution of the heating program? A dehumidifier was placed in one of the rooms, but in my opinion it was emptied too infrequently (whenever I was there, the container was full and was emptied by me).

The basement itself is constructed as a white tank and the seals also looked good. However, it rained several times during the heating phase.

Thank you very much for your tips.

Hello "Clausen77". Some things in construction technology cannot be clarified, or only with considerable effort. I am writing this to you once as an expert in the field! In the case you described, I would actually follow the site manager's advice and wait to see how the situation on the lower wall surfaces develops. It is definitely not due to the "wrong heating program." And whether it makes sense to set up forced dryers depends on the indoor humidity you measure at which room temperature. "Weiße Wanne" does not mean "vapor diffusion tight," but tight against liquid water. What is visible in the photos is by no means dramatic. But one should watch the whole thing attentively, without "scaring the horses!" -------------------- Regards: KlaRa

Hello KlaRa, thank you very much for your assessment and for taking the time to respond so thoroughly. That reassures me a little. I will continue to report on what still happens regarding the screed.