Which impact sound insulation is suitable for underfloor heating?

Hello,

we will soon be installing laminate or engineered wood flooring in the children's rooms and the parents' area. Until now, we have always laid a 5mm impact sound insulation under it or fully glued the parquet. However, now we have underfloor heating, and therefore the floor construction should allow the heat to pass through as well as possible.
Is there a specific impact sound insulation that would be well suited for this, and how thick should it be? Have you had good experiences with certain products?

Best regards
Sabine

Look at the individual materials, there is always a legend indicating whether suitable for underfloor heating or not and if so, how well.

In every hardware store, building materials store, and specialist floor covering store, there are also suitable mats. Get advice in various stores here. We have laminate from BHK, therefore also the 1.8mm thick impact sound insulation with a vapor-tight underside (glued into a vapor-tight surface over the entire area with special aluminum adhesive tape). Alternatively, there is a very similar foil from Parador. Certainly also other suppliers. Both about €4/m². Usually, the foils only state whether they are suitable for underfloor heating, but not what thermal resistance they have. It is also quite difficult to find out, if necessary always ask the manufacturer. In my experience: advisors usually are not very strict about that and sell the product that is in the store. For value differences of 0.01 something in resistance they are not very interested. I also cannot assess whether and how much that ultimately brings.

Hello Sabine,
in principle, I recommend full-surface bonding for parquet. Better heat transfer = lower heating costs, less tension / joint formation, quieter walking noise (in the room itself), easier to sand,...
Laminate can generally not be glued because a) it is usually excluded by the manufacturers and b) economically (glue price : laminate price) it would also be a small disaster...

For laminate (or parquet if you want) choose an underlay with a very low thermal resistance (not to be confused with the thermal transmittance coefficient).
Here 0.01 m2K/W or less (top values are around 0.004 m2K/W) is recommended. For comparison: cork with 2 mm thickness has 0.040, a standard foam foil as well. So 4 to 10 times more...

The thickness of the underlays is ideal at 1.5 to 3 mm.

For example from HARO
Silent Pro DS
Silent Energy DS
Silent Eco DS

or Parador
Akustik Protect 100

so 2-3mm thickness would probably be enough, Parador offers 1.8mm and 2.8mm. We will also buy our laminate from Parador, we chose it yesterday.

Best regards
Sabine

If you take the one from Parador, it would be the Akustik protect 100 (=1.8mm). This thickness is completely sufficient for the expected surface condition of the heated screed. A thicker underlay would only be necessary for extremely rough, grainy surfaces.
The 2.8mm version does offer better impact sound insulation (but the 1.8mm is very good too!) but is only half as pressure-stable. Personally, I find stability more important.
In the end, you can't go "wrong" with either of these options.
Advantage of both: the vapor barrier (aluminum side facing upwards!) is already integrated.