which sound insulation?

[CharlotteJ]

Hi, having read through loads of posts about sound insulation, I am still confused!

 

Our builders merchants have recommended Isover APR1200 75mm for our 100mm studs.  Density is 12kg/m3. Cost approx £4.09 per m2

From this forum, Rockwool RWA45 75mm is recommended often, Density 45kg/m3. Cost approx £6.19 per m2.

 

Ive read conflicting views on higher density being better.

 

We are thinking of boarding each side with blue plasterboard - does this make much difference, or would two standard plasterboard with staggered joints be as good - less heavy to deal with!

 

Any other product recommendations or advice/experiences please?

[JohnMo]

We used Rockwool Flexi, but most products are similar except PIR which is rubbish for sound. Your insulation material needs to be thinner than the stud so neither side touches the plasterboard.

 

Denser insulation stay in place well, but needs more careful sizing. Gaps are bad and will circumvent the insulation.

 

We used standard 12.5mm and dry lined no issues.

[nod]

Isover is the best 

50 mil is plenty 

[Thorfun]

4 hours ago, CharlotteJ said:

Hi, having read through loads of posts about sound insulation, I am still confused!

 

Our builders merchants have recommended Isover APR1200 75mm for our 100mm studs.  Density is 12kg/m3. Cost approx £4.09 per m2

From this forum, Rockwool RWA45 75mm is recommended often, Density 45kg/m3. Cost approx £6.19 per m2.

 

Ive read conflicting views on higher density being better.

 

We are thinking of boarding each side with blue plasterboard - does this make much difference, or would two standard plasterboard with staggered joints be as good - less heavy to deal with!

 

Any other product recommendations or advice/experiences please?

ultimately it depends on how much dampening you want and how much money you want to throw at it!

 

we used Rockwool throughout and standard 12.5mm plasterboard on both sides of internal walls. we do get sound transfer but then again, it's a house and not a museum so we don't mind a bit of transfer. besides, more often than not doors are left open so no amount of sound insulation is going to fix that! 🤣

 

i'd suggest RWA45 personally. nicer to work with than the Isover stuff afaik and it stays in place between the studs well.

 

we put 50mm in the walls and 100mm in the ceilings

[Nick Laslett]

You need to look at the performance tables from British Gypsum or Siniat GTEC, etc. 

 

This picture shows the acoustic performance of a simple 12.5mm timber stud wall, 35 is the key number. 

 

Next picture shows more variables, double boarding or insulation 16km/m3. Number now is higher than 35, this is better. 
 

 

 

You can find these performance tables from most plasterboard manufacturers, sometimes in a document called the White Book. 
 

Sound insulation is a complicated topic. There are three types of sound transmission that you are trying to control. I have a post about it here already. 

Edited Wednesday at 16:58 by Nick Laslett

[CharlotteJ]

Thanks so much for all the info, particularly the picture, very interesting and informative.  We're going to try and insulate as best as possible as have two elderly relatives living with us who have their TV very loud!

[Nickfromwales]

20 minutes ago, CharlotteJ said:

Thanks so much for all the info, particularly the picture, very interesting and informative.  We're going to try and insulate as best as possible as have two elderly relatives living with us who have their TV very loud!

Have you investigated resilient bars?

 

Pay particular attention to ceiling voids; in a previous clients build we doubled up the acoustic insulation in the ceiling voids, and made a 200mm wide acoustic wall to prevent sound going ‘up and over’ as this was a music/piano room. So fully filled the stud walls, doubles up in the ceiling, and we could have gone with acoustic PB but the builder had already ordered regular boards without consulting me as the clients consultant (before he ran off, and we adopted the completion of the build!), and no complaints so far. 
 

Resilient bars on walls can also help with acoustics, but I’d defo use 15mm sound block/acoustic plasterboard induce the TV room, on the ceiling there, and also on the other sides of those stud walls. 

[Mike]

See also this thread:

 

 

[Nick Laslett]

@CharlotteJ, here is the text of a post I made recently about the sound insulation topic.

 

Quote

 

Good sound proofing, is a bit like airtightness. The devil is in the detail. 
 

Types of transmission :

1.Airborne noise

Sound that uses the medium of air to travel through. Common example include talking, music and TV.

 

2.Impact noise

Sound generated by two materials coming into contact, sound vibrations travel through the materials. Common examples are footsteps and washing machines.

 

3.Flanking Transmission

When sound vibrations travel over, under or around a barrier. This could be using holes in walls made by light fixings, shelves or picture hooks. Another common example is pipe work which can vibrate with sound waves and travel between various rooms.

You need to cover how each one of these types of transmission will be reduced, with Decoupling, Insulation and Absorption. The plasterboard absorbs the sound. Resilient bars create the Decoupling. Glass Fibre or Rockwall gives the insulation. More, thicker plasterboard the greater the absorption. 

 

Other simple wins:

 

Standard doors will undo a lot of the benefit from a solid wall. 
 

Sound transmission through down lights. 
 

The wrong type of MVHR configuration can also carry sound between rooms. 
 

Don’t have plug sockets and light switches back to back in a wall between two rooms. 
 

I quite like this YouTube channel. They have a website too.
 

http://www.youtube.com/@iKousticSoundproofing

 

This website has lots of guides. 
 

https://soundstop.co.uk/pages/soundproofing-guides

 

Here is a really good YouTube video from Ali Dymock that covers a lot of the concepts for sound proofing a wall.