Impact sound/thermal insulation glued under multilayer parquet

Hello everyone,

I searched in the forum but didn't really find the appropriate thread, so I'm starting a new one.

In an apartment on the ground floor of a 70s building, I would like to install engineered wood flooring. The ceiling of the basement below is not insulated. From experience over the last winters, I can say that the floor gets quite cold. Therefore, I started looking for an impact sound insulation that also has thermal insulation properties. I ended up with cork. However, since I want to glue both the underlay and the parquet itself, I need a glueable alternative to regular cork. Floating installation is ruled out for several reasons in this case.

I had a company recommend the Kork-Pur underlays from Knauf (3mm) in combination with Knauf adhesive for this purpose.

What do you think? The internet doesn't really provide much... Surely there are other recommendable products that serve this purpose.

Thank you in advance.

Best regards

I had a company recommend the Cork-Pur sheets from Knauf (3mm) in combination with Knauf adhesive for this purpose. What do you say about that?

From an insulation perspective? Nothing, as it is ineffective. As impact sound insulation? When gluing the parquet, nothing at all, because below you is a basement. Nobody is disturbed by impact sound there and in the apartment the effect is barely noticeable. Are you the owner of the apartment, the house, or just a tenant? I want to point out that 5cm of insulation under the basement ceiling is much better than having no cork insulation at all.

Thank you for the quick response!

Ineffective? Then why is cork praised everywhere for its great thermal insulation properties and specifically pointed out as not to be used in connection with underfloor heating, precisely because of these properties?

In this house, everyone is bothered by impact noise and the insulation must be as good as possible. Here, heating pipes are installed under the screed in such a way that they touch it. In many places, there are acoustic bridges directly to the walls, etc. That means my impact noise also travels further up or to the neighbors via the pipes.

I am the owner of the apartment, no, I will not pour new screed.

The basement ceiling will not be insulated in the near future.

Ineffective? Then why is cork praised everywhere for its great thermal insulation properties and explicitly pointed out not to be used in connection with underfloor heating, precisely because of these properties?

The same is said about parquet – it just doesn’t conduct heat well. That’s why it feels "warm underfoot," even if the floor has no different temperature than tiles.
Yes, it insulates about as much as poor mineral wool or similar – but you only have 3mm. To insulate a wall, for example, to today’s standards, you need around 18-20cm of cork. That’s why the statement is that the 3mm is homeopathic and you won’t notice a difference.

In this house, everyone is bothered by impact sound.

Impact sound is the sound perceived BELOW you. Below you is only a basement, so impact sound insulation doesn’t matter.

Here is my brief answer to the initial question:
1. You either have impact sound insulation or thermal insulation. A construction layer that can satisfactorily accomplish both does not exist.
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2. Cork as board or roll material as thermal insulation is a wishful thinking, nothing more.
"Nordanney" has correctly stated everything there is to say about this!
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3. You are planning (in principle only) internal insulation. Fine, it will never achieve the desired effect, but basically anyone dealing with internal thermal insulation should thoroughly study the basic principles of building physics beforehand. Keyword: "How do I get the dew point below my parquet with little money and knowledge?"
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4. If installations are laid in the screed, it cannot be made according to standards. Here the general question arises as to where such knowledge comes from.
Quote: "Here heating pipes are laid under the screed so that they touch it."
It is difficult to understand who or what should be touched and how this was determined.
To summarize:
a) CORK is not a usable thermal insulation material, no matter who claims that cork can take on this task.
b) 3mm cork as thermal insulation is also unrealistic!
c) Thermal insulation is always applied on the cold side of a component and only in certain cases together with a vapor barrier on the warm side. The insulation for uninsulated floors above ventilated (i.e. cold) basement rooms should be around 10cm on the basement ceiling. Everything else is nonsensical because the heat transfer cannot be reduced.
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Knowledge from the internet can—especially in construction—lead to significant damage due to acquired ignorance!
Hoping these my lines will fall on fertile ground: KlaRa