How to fix acoustic plasterboard to block wall without dot and dab?

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DomK1234

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Hi there,

Looking to add acoustic plasterboard to internal block walls (100mm) just as a general noise dampening measure but have read that using dot and dab should be avoided as the resulting spaces between wall and board can ask as sound amplifiers. For a beginner DIY-er, what would be a good alternative to fix the boards to the walls?
 
Board foam.

Proper way is resilient bars. Don't let board touch edges like the floor or walls.
When fixed fill edges with acoustic mastic. Plaster.

If you go with foam don't let boards touch edges again.
 
Lovely, thank you.

Might the foam have similar issues to the dot and dab, in that there will be air pockets between boards and walls, or is the idea that the foam fills much more of that internal space so it's less of a problem?

Noted about the edges, thank you.
 
I have seen people in AV forums recommend that you fill the void with expanding foam (after using dot and dab adhesive).

You would need to drill a series of holes in the plasterboard and squirt in the expanding foam to close the cavity. You might however need to drill a lot of holes.

Ideally you would drill holes the same size as the end of your foam gun (or straw if not using a gun). The holes are important, they act as both entry and exit points for the expanding foam. Without them, you risk making the plasterboard bow outwards.
 
DomK1234 said:
Hi there,

Looking to add acoustic plasterboard to internal block walls (100mm) just as a general noise dampening measure but have read that using dot and dab should be avoided as the resulting spaces between wall and board can ask as sound amplifiers. For a beginner DIY-er, what would be a good alternative to fix the boards to the walls?
Click to expand...
Where did you read that nonsense?
 
I did a project in my TV room. It was a battened wall with 2x3 but not touching the original wall and the bottom and top sections were separated from the ceiling and floor via a rubber acoustic barrier. Then one coat of sound PB then another layer ontop of that but in-between them used a product called Green Glue to separate them. The gaps between the 2x3 were filled with sound insulation rockwool slabs.
 
Sound travels through solids.

If you had foam with metal sheet then foam suspended in the air then sound won't get through as the metal will move in between the foam canceling out the noise.
Foam don't block noise but allow the solid to move (plasterboard) which will create a sound barrier.
If the board touches the side walls ect then the sound will travel this route and continue on.
 
foxhole said:
Think you misunderstood .
Click to expand...

I have seen the manufacturers of the sound insulating boards saying that the dot and dab empty cavity can amplify noises. I would imagine that they know what they are talking about, especially given that recommending against dot and dab will result in a degree of lost sales.
 
Wayners said:
Sound travels through solids.

If you had foam with metal sheet then foam suspended in the air then sound won't get through as the metal will move in between the foam canceling out the noise.
Foam don't block noise but allow the solid to move (plasterboard) which will create a sound barrier.
If the board touches the side walls ect then the sound will travel this route and continue on.
Click to expand...

My, lay, understanding is that very low frequencies travel through solids, not higher frequencies.

It seems that the ability of expanding foam to dampen noise is often overrated and that mineral wool would be better, but in the OP's case the foam will fill the void if they go down the dot and dab route. I guess another alternative is to batten the wall and use mineral wool to fill the gaps between the battens.
 
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