Screed qualities in the field of anhydrite / cement screed

Hello everyone, we will be building a single-family house with approximately 200 m² of living space this year. The underfloor heating (air-water heat pump) is installed within the screed. The topic of screed is still a mystery to me and currently doesn’t let me go entirely. After researching within this forum, some questions and qualified answers have already been given, but the actual advantages and disadvantages are still not entirely clear to me (by the way, every company I asked says something different :-)) I will summarize my modest level of knowledge: Cement screed (flowing screed): Positive: water resistance Negative: prone to cracking, prone to cupping, somewhat more expensive, joints must be inserted in large areas Cement screed (site screed smoothed): Positive: water resistance, less water and thus drying time, less prone to cupping Negative: prone to cracking?, much more expensive than anhydrite or flowing cement Anhydrite screed Positive: no joints in large areas, quite affordable Negative: water resistance Question: How do the variants behave with regard to the installed underfloor heating? Anhydrite screed is often advertised as "heating screed." Is the effect actually that much better than with cement screed? The interior finishing will be done completely as drywall (gypsum plasterboard). Is my concern about the high moisture with flowing screed justified (gypsum plasterboards are known to readily absorb moisture) or is it negligible? Considerations: Basically, I was leaning towards using completely cement screed (flowing screed) because it is self-leveling. However, I keep being told about the issue of cupping, etc. The alternative, doing everything with more effort and "drier" as site screed (smoothed), is allegedly quite expensive (but we don’t have a quote yet). Anhydrite wasn’t initially considered, but the topic of "seamless" (kitchen, living, dining are about 50 m²) is basically interesting. I am actually afraid here regarding the issue of water resistance. I look forward to your experiences or suggestions Thank you very much Sebastian

Question: How do the variants behave in relation to the installed underfloor heating?

So that you don't notice any difference.

In terms of price order, you will mostly get the order cement screed, cement flowing screed, and anhydrite screed (calcium sulfate screed).

The interior finishing will be done completely as dry construction (gypsum plasterboard). Is my concern regarding the high moisture with flowing screed justified (gypsum plasterboards are known to absorb moisture easily) or is it negligible?

It is negligible. Every screed brings moisture without end. And you have to wait a bit anyway before you can start with the interior finishing.

Anhydrite was initially not up for discussion, but the topic "seamless" (kitchen, living, dining is around 50 m²) is basically interesting. I am actually afraid regarding the issue of water resistance.

Whether seamless, your screed installer will tell you.
Regarding water resistance, you have to answer the question yourself how often you have spread hundreds of liters of water on the floor in your apartment or house. If a bucket of water tips over, it is mopped up and then that's it. It is about a lot of water penetrating the screed. The topic only really arises in the bathroom or in the event of actual water damage, for example due to a broken water pipe.

Screed is really the easiest trade, it doesn't matter at all what you do there. All the same stuff :)

Anhydrite screed receives a sealant in the wet area and thus the issue is resolved.

Thank you for the quick initial feedback.

: Your price range goes from expensive to cheap? (at least that's what I assume)

The issue of water resistance is not so easy for me to answer. Clearly, something has to happen for water to reach the screed. However, with a water-based underfloor heating system, I am already exposed to a "risk of water damage" with all the connections (not to mention the dangers of leaking pipes). I also have this with cement screed, but supposedly it can be professionally dried. Or am I being too critical?

What do you think about the option of using anhydrite in the living area and cement in the bathroom (the tiler has to level the flush shower anyway and can basically do the bathroom as well)? Practical?

@nordanney: Your price order goes from expensive to cheap? (at least that’s what I assume)

The other way around, cheap to expensive.

Or am I being too critical?

Yes.
Calcium sulfate screed is state of the art. Leaking pipes are also almost impossible since each circuit consists of only one complete pipe (no splicing). And the connections are not "leakier" than any other connections.

What do you think of the option anhydrite in the living area and cement in the bathroom (the tiler has to level the floor-level shower anyway and could basically do the bathroom as well? Practical?

Yes and no. The tiler should properly work out the shower including drainage. The screed layers usually don't do that. But the tiler will not do the screed for the entire bathroom. However, there is no reason not to cover the bathroom with calcium sulfate screed as well and then seal it properly. The complete sealing is highly recommended even with "normal" screed.