ᐅ Thick impact sound insulation, differences from thermal insulation

Hello everyone,
we will soon be the owners of a solid brick house from 1900, without a basement, and not insulated.

We want to install laminate flooring in some rooms. Now the question is which underlay for impact sound insulation to use and how thick it should be. In stores, there are various options, 2.2mm (0.09 inches), 3mm (0.12 inches), 5mm (0.20 inches).

Are there significant differences in thermal insulation depending on the thickness of the underlay?

Looking forward to your answers.
Thank you

Impact sound insulation primarily serves to reduce noise from footsteps, to even out minor unevenness in the subfloor, and, if applicable, to provide a seal against residual moisture from the screed. If no moisture protection is integrated, an additional vapor barrier or foil is usually required. The thickness of impact sound insulation is generally too low to provide significant thermal insulation. When using underfloor heating, it is important to have a very low thermal resistance, which usually means using a very thin layer of impact sound insulation, for example, up to a maximum of 2mm (0.08 inches). Without underfloor heating, a thicker layer will contribute more effectively to thermal insulation. In this case, compressive strength should also be considered to prevent excessive floor deflection or a bouncing effect under load.

It is best to consult a professional who can review your floor construction and requirements in detail.