Underfloor heating: should it be installed wet or dry?

Then have a calcium sulfate flow screed and warm water heating elements installed as the standard solution for underfloor heating. All other considerations are not sensible and come with disadvantages! Regards: KlaRa

Could you elaborate on that a bit?
Why necessarily calcium?
What are the disadvantages of all other systems? Don’t they also have supply temperature advantages?

Why calcium sulfate and not cement screed? Good to know for the second house perhaps

Hello "Kaspato". One can build "according to standards" in construction or use special constructions. The former work, the latter can work and are mostly used in existing buildings or when building according to standards is not possible - for whatever reasons. With all the associated risks, but usually there is no other solution. In residential and commercial construction, warm water underfloor heating systems embedded in wet screeds are standardized according to DIN 18560 Part 2. This has worked perfectly fine for many years. However, flowing screeds should be preferred, since the connection between the binder and heating elements cannot provide better heat transfer. Now to the second topic: calcium sulfate or cement flowing screed? The damage patterns that occur in practice due to drying-related shrinkage stresses, especially in cement-bound flowing screeds, have been observed by me for many years. To shorten it: the manufacturers' promises have not been fulfilled in practice (at least in most cases) .... For this reason, this screed is also not standardized! It is therefore a "special construction" that must be coordinated with the client and all disadvantages must be stated beforehand. The stresses in purely cement-bound flowing screeds are almost impossible to control. It looks different with calcium sulfate flowing screeds (CAF). These correspond to the technical rules - and are also listed in DIN 18560-2. --------------------------------------------- To sum up, the task of the respondents in this forum is to provide askers with a technically correct answer so that they can apply the associated (possibly new to them) findings in their practice. And that is - at least I hope - achieved through my answers. Regards: KlaRa

In the floor heating standard DIN EN 1264, they are referred to as "systems with pipes within the screed - Type A and Type C" (wet system) as well as "systems with pipes below the screed - Type B" (dry system).

found during a search for "fußbodenheizung trocken DIN".
So this is not really a "special construction".
and I think that there can certainly be more than one "standard".

The standard you mentioned also seems to refer only to wet screeds, not to floor heating systems.
In variant B (dry) for floor heating systems, the floor heating is BELOW the screed. This screed can still be a wet screed according to your standard.

@ Kaspatoo: I recognize that it is better to leave it as it is at the current state. I myself do not obtain my information (especially the necessary background knowledge) from the internet, but it is my daily work to know different standards with comparable content, to interpret their contents and to summarize them precisely. Especially for courts, in order to provide the presiding judges with a basis for their decisions. In this respect, my statements apply without restriction as previously described. The different types of construction that you apparently have now clarified actually have nothing to do with the questioner's topic, nor with my response, and form a self-contained topic within the types of standardized underfloor heating systems in wet screeds. The type B of underfloor heating has nothing to do with prefabricated screeds (dry systems) but only that the heating elements are embedded in the upper edge zone of the insulation layers. Otherwise, in practice, it is a rather less commonly used type. ----------------- Best regards: KlaRa