Priming and painting gypsum boards before screeding

Good morning everyone,

I have been working since last August to renovate a house that was unoccupied for 10 years and bring it up to the latest standards. I had already started filling the suspended ceilings made of gypsum board and wanted to paint them when someone told me that the boards should not even be attached yet because the screed has not been laid.

My questions now are, does it make sense to prime and paint the ceiling in advance? I don’t want to waste any more time on other things. Does the primer and paint even protect the filler from rising moisture?

Answer:
After installing a screed, ventilation should be avoided for a few days (depending on the binder) to prevent premature water removal from adversely affecting the screed's strength. It is quite possible that the (mixing) water evaporating from the screed runs down the window panes.
Ceiling elements, e.g., based on gypsum fiber, are not expected to be exposed to moisture except in a bathroom. Therefore, they are not "waterproof." They will warp under the influence of high humidity.
For this reason, it makes sense to first install the screed and allow it to dry before installing the ceiling elements!
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Regards: KlaRa

My predecessor is absolutely right. There was plasterboard on the ceiling before the screed came, with the result that after it arrived, some panels were replaced because they had been ruined by the moisture from the screed.