Sound insulation in timber frame construction. Recommendations?

Hello,

we are building a single-family house using timber frame construction: basement, ground floor, and upper floor.

Between the basement and the ground floor, the spaces between the rafters are insulated with cellulose. The roof is also insulated with cellulose. The ceiling from the ground floor to the upper floor is empty, as it does not need insulation. Now we have been thinking about whether it would make sense to fill these cavities with something to better isolate the ground floor from the upper floor in terms of sound. Any recommendations?

Thanks!

Sure, unfilled it's a great sounding body, so put in as heavy a filling as possible (mineral wool/rock wool, better yet blow in loose fill) against sound transmission. However, it should not be completely filled, 50-60% of the rafter height is sufficient.

Something with as high a mass as possible. Rock wool, for example. Then lay impact sound insulation mats on the wood on top, and then the floor covering on that.

Blow-in loose-fill insulation or cellulose blown-in insulation. Mineral wool does not have enough mass.

The transmission of high as well as low frequencies is to be prevented. Pure mass alone does not help, but it is already a good solution. Various layers of solid "mass" as well as a soft layer for decoupling help even more. However, the question actually comes a bit late here. It is of course always better if something like this is planned directly by the architect so that the entire floor structure can be aligned accordingly. How is the floor structure of the upper floor planned?

Achjay

But it shouldn’t be filled completely, 50-60% of the rafter height is enough.

Why not fill it completely? Do the 50-60% have a reason? In terms of costs? My beams are 24 cm. So I could blow in 24 cm.

Expanded clay fillings or cellulose blown-in insulation. Rock wool does not have enough mass.

Fillings are mainly good against impact sound, right? Unfortunately, that doesn’t work structurally for us, since it’s a large, open room layout. I’m mainly concerned about sound from speaking.

How is the upper floor structure planned?

Floating cement screed on thermal and impact sound insulation (rigid foam boards and mineral fiber boards). After that comes a special mat against impact sound from the floor layer and then vinyl is laid on top.