Alternative soundproofing materials

[davejaydj]

I have read on soundproofing suppliers websites that their accoustic mineral wool (for laying under the floorboards) is twice as effective as ordinary loft insulation. As loft insulation is so much cheaper, with many DIY stores offering big discounts, what's to stop me putting in two layers of loft insulation (depth of joists permitting)?

 

[mointainwalker]

I don't know but I would think nothing.

I looked up the weight per m2 of Rockwool sound insulation and thermal insulation of a similar thickness and , from memory the sound insulation was about four times heavier.

When I need to do it, I'll try to jam in as much thermal insulation as possible.

 

[big-all]

filling in the voids will have little effect on the sound transfer are most the sound transfer is through the structure
also doubling the the amount off heat insulating material in the same space is a waste as its trapped air that holds the heat

 

[mointainwalker]

@big-all

The comment about filling the void was made purely concerning sound-reduction - as that is what the thread is about - and not thermal insulation.
The comment about thermal insulation is used only to identify the material I would use and its density

As regards how much noise is transmitted by which part of the wall, I would think that is hugely complicated and depends on the type of noise.If you could point me to any sources that quantify relative transmission I would be interested

I believe that stuffing the cavity will give you some noise reduction ,"relatively" cheaply but should only be done after all holes/gaps have been sealed.

 

[big-all]

yes i fully agree that you do get some good as in high frequency is reduced but unfortunatly its always the low frequency bass that causes the problems
a carpet and underlay will give you more reduction in sound than stuffing lightweight insulation in

indeed sand is a good insulator because off the weight it deadens the resonance


but dont try that at home

 

[mointainwalker]

big-all

Does that mean that my self-levelling 6 cm screed being laid on top floor of my house with bedrooms below will give very ood noise-insulation ?

 

[big-all]

unfortunatly its solid so it will still resonate but because its heavy will probably absorb most off the noise