Insulation in joists, noise level

[Lewdis]

My mom lives in a turn-of-the-century house and it is very noisy between the floors. Now they have torn up the floor in the "attic" and under the plank floor there is a gap before the insulation comes in.

My question is whether it is correct that the insulation does not fill up completely to the height of the beams, to the floor. If there is an air gap between the floor and insulation, can this affect the noise level for the residents below positively or negatively?

 

[huggan]

A 95 mm disc is recommended for the intermediate floor. It is beneficial to have full-height insulation, but not much.

 

[Lewdis]

A 95 mm disc is recommended in the intermediate joist. It does help to have full-height insulation, but not much.

So you don't think that the sound bounces in the joist and increases the noise level for the residents below when it's not filled with insulation all the way up?

 

[huggan]

It does so even with full insulation, so of course I consider it. But which measures are economically justifiable to implement? If you get an improvement of 0.1%, is the measure worth doing then?

Normally, you either add another layer of insulation under or above the beams, or use acoustic beams to which you attach the ceiling or floor gypsum on top. These measures are often much more effective than just throwing in insulation between the beams.

It is materials with high density that stop sound, so insulation is not a good product except for certain high-frequency sounds.

Are new apartments going to be furnished in the attic?

 

[Gabbe1]

In intermediate floors, wood shavings/sawdust is a better choice if the primary goal is to insulate against sound.