How thick Rockwool?

[ashthekid]

I'm close to plasterboarding my project out and in between all the timber studwalls which is 2x4 I'm wondering exactly what thickness Rockwool to put in.

So 2x4 gives me approx 98mm depth, shall I go for 100mm Rockwool and cram it in or is it best to have some kind of air gap as well for soundproofing so perhaps just put 75mm or 50mm.

I guess what I'm asking is does it make a big difference to the soundproofing?

 

And what about in between floor joists? I have 25mm chipboard on top, with another 20mm underfloor heating board on top of that so 45mm 99% everywhere upstairs. 

What amount of Rockwool for the best soundproofing possible?

[JohnMo]

I used 70mm, you don't want it to touch the plasterboard, as it will transfer sound

[Conor]

You need a gap, for our 70mm studs we used 50mm isover and for the 150mm ceiling void we used 100mm. So 70mm would be bang on for you.

[ashthekid]

There's a really good deal on Knauf 50mm rolls at the moment, would that be sufficient? Do think a big enough difference in soundproofing between 50-70mm to warrant the extra cost?

[ashthekid]

What's the best brand for optimum acoustic efficiency?

Knauf, Rockwool, Isover?

[JohnMo]

No reason why 50mm wouldn't be acceptable.  Which ever brand you use they are doing the same thing to mitigate noise.

 

I think 25mm is the minimum acceptable thickness.

 

https://www.ursa-uk.co.uk/applications/acoustic-insulation-floors-and-walls

[matthyde83]

Sorry to hijack… I have a tv room that is separated by the rest of the house by a cavity wall.  I’m using thermabeads everywhere else but there’s the opportunity here to put something different in the wall to increase sound resistance… 150mm cavity.  What are thoughts?

[Iceverge]

Pour in a few hundred kg of concrete. 

[markc]

8 minutes ago, Iceverge said:

Pour in a few hundred kg of concrete. 

That would work

[TonyT]

100mm

[Onoff]

7 hours ago, matthyde83 said:

Sorry to hijack… I have a tv room that is separated by the rest of the house by a cavity wall.  I’m using thermabeads everywhere else but there’s the opportunity here to put something different in the wall to increase sound resistance… 150mm cavity.  What are thoughts?

 

Soundbloc pb on the walls for a start. It's magic. 'kin heavy but magic! 😂

[ADLIan]

Assuming concrete/medium density block on both sides then acoustic performance will come from the mass of the wall. Adding mineral wool or dense plasterboard will add little, if anything, acoustically.

[matthyde83]

2 hours ago, ADLIan said:

Assuming concrete/medium density block on both sides then acoustic performance will come from the mass of the wall. Adding mineral wool or dense plasterboard will add little, if anything, acoustically.

I do suspect it’ll deliver good sound results so may not be worth any extra effort and just let the beads go down?