Usefulness of acoustic plasterboard on its own against solid wall

[u587162]

Our internal block partitions have been built, most of which are load bearing.

We will be installing acoustic plasterboard on most of these walls.

Am I right in thinking that without any acoustic rockwool between the block wall and the plasterboard, the acoustic properties will not be that great or non existent? Should we still consider installing at least 25mm of the rockwool at the detriment of space loss and is there much more work for the builder involved?

Thx.

 

[^woody^]

That type of plasterboard on a block wall is a complete waste of time.

Like your decorative eave question, you should not be just throwing random things together to acheive something.

If you want sound proofing to a particular standard, then it should be designed from the start, not cobbled together. And then you need to know that what you are doing is actually better than not doing it.

You could use a different product to replace the plasterboard and rockwool, but you need to have an idea of what you are actually trying to acheive.

 

[u587162]

What I want to achieve is a sound insulated wall which as I have already explained, is a block wall.

Please rationalise your answer when you say there is no point.

As to the eaves question you are assuming I don't live in a street with period features. Why did you assume that. I simply asked how I could install certain decorative detail if my windows are too high up and then you go into a tangent about it looking out of place when I never examined the street scene.

 

[^woody^]

What I want to achieve is a sound insulated wall

Which is the existing masonry wall.

What extra do you hope to acheive?

Adding stuff to the front of a wall which is already well insulated for sound does little, as sound then travels around the wall through other parts of the structure - parts of the structure which you are not dealing with - which makes your plasterboard proposal pointless.

 

[mikkymo]

Sound Isolation requires MASS and AIR in order to damp the vibrations caused by sound waves. Ideally you'd have a room-within-a-room scenario where the inner walls, floor and ceiling are all decoupled from the outer structure using compliant isolation strips, such as neoprene or EPDM. When you have sound within the room, the sound waves hit the first wall with a degree of energy. This inner/first wall will move/oscillate and reduce the energy of the sound wave. The remaining energy would be reduced as it tries to pass through the dense rockwool inside the cavity. Once it hits the second wall, the energy will be further reduced.

A block wall has a huge amount of mass anyway so as woody has said, acoustic plasterboard attached to it would be pointless. You can't simply whack up a stud wall and fill it with rockwool either as you aren't considering the floor, ceiling, doors, etc. which contribute to 'flanking noise' as woody has also said.

Sound Isolation is a science. I'd recommend reading Rod Gervais' book called Home Recording Studio. Google it.

 

[chappers]

If you have used concrete blocks for your internal walls I wouldn't bother, the next upgrade would involve too much work for partitions within the same dwelling to be worthwhile.

 

[ey143]

Out of curiosity, would a thermalite block wall be a better or worse sound insulator than a dense concrete block wall?

 

[noseall]

Out of curiosity, would a thermalite block wall be a better or worse sound insulator than a dense concrete block wall?

Dense every time.
If there is one thing sound does not like to pass through it is dense materials with mass. Hence, lead lined walls for sound proof booths.

 

[^woody^]

There is no "better" between them, as any performance difference will be indistinguishable in use in the home, and difference will be on paper only.

The construction, finish and detailing will be the relevant factors.

 

[jeds]

Out of curiosity, would a thermalite block wall be a better or worse sound insulator than a dense concrete block wall?

Not that simple. Sound is made up of a range of frequencies and different materials attenuate different frequencies at different rates. A very loose rule is that higher mass attenuates lower frequencies and vice versa. Think of times when you can only hear the bass sounds. That's because the materials between you and the source are attenuating the higher frequencies but not the lower bass frequencies. At the other end of the scale think of tapping on an old heating pipe. The high mass metal attenuates the low frequencies but the high pitched tap-tap sound travels easily along the pipe. Very handy for tapping out a night-night Johnboy message to your fellow scrotes when you're next in prison. For decent sound attenuation you need high mass and low mass and also air voids are useful. That said, for most normal domestic sounds a decent heavy separating wall will do a job.

 

[u587162]

What I want to achieve is a sound insulated wall

Which is the existing masonry wall.

What extra do you hope to acheive?

Adding stuff to the front of a wall which is already well insulated for sound does little, as sound then travels around the wall through other parts of the structure - parts of the structure which you are not dealing with - which makes your plasterboard proposal pointless.

If by "which is the existing masonary wall" you mean what walls are solid, we do indeed have several new thermalite block wall partitions for several of the first floor rooms which are taking the weight of the RSJs. Builder has already quoted for acoustic plasterboard in the contract price so I'm not paying any extra.
To answer my question however, is the correct process however that the plasterboards are secured directly onto the walls in the picture shown below?

>>The construction, finish and detailing will be the relevant factors.
Pls expand on the above line with reference to the photos of how you might do this? Thx.