Using sand for soundproofing

[Phil L]

Obviously not if it's used by professionals who do it for a living.

Rockwool is made from rocks, hence it's name, so if you stuffed the box full of rockwool, fairly compressed, you are saying it wouldn't make any difference?

If it's a flimsy piece of rockwool, yes, not if it's compressed so that it has less air and more rock...it becomes similar to sand, but without the drawbacks

[Doctor Drivel]

acoustic stuff. Anything acoustic is expensive. I know one fella who built his own house and checked the specs and rigid Rockwool bats performed only slightly less than the dedicated stuff at a fraction of the price. This may be a new line.

[Phil L]

It may have been just the normal batts, and I've remembered something else too, they stapled long strips of what looked like thick underlay along each joist prior to laying the final matting and boarding, this was similar in structure to the cushioned rubbery stuff, but thicker, about an inch, I'm told.

The overall difference was extremely effective, although I think it came to around 8K for a 80m2 approx area, but the club owner and the restaurant owner split this between them.

[MJ]

I've done 3 types of sound insulation in my house.

1. Party wall insulation. 2x2 battens and plasterboard with rockwool filling the gap. Total waste of time. A friend also did it after I told him my results but he had to try it himself. Another total waste of time.

1. Another party wall insualtion. A 2x2 batten/chipboard sandwich filled with sand then attached to the wall against more 2x2. Rubber insulating strip at all points of contact. Highly effective. Bass from a 300w + 2 150w subwoofers at max volume can be heard next door but muffled. At normal volumes, which isn't quiet - not a thing. But if I had to do it again I might consider if just building another brick wall would be easier and just as effective.

2. A bedroom floor insulated with sand. Battens screwed to joists then chipboard panels. I sealed the gaps with silicon sealant then lay plastic sheet down. No loss of sand and it helps with lifting the sand should you need to get below (light fittings for example). About 2 inches of sand. Maybe 3 - not sure. Reasonably effective. I'm able to compare this bedroom with the one next to it as they're both over the living room, and there is a noticeable difference.

If you don't have mass, you're wasting your time.

Mike E.

[The Natural Philosopher]

Yup. Thats the stuff they stick on car body panels to soundproof them Its sticky and its HEAVY. And expensive.

Th erockwool deals with the high frequencies reasonably, but that's all. You need MASS. and ideally mass with low elasticity..

[The Natural Philosopher]

That is not what people mean by rockwool.

I am not sure that rockwool is made of rock either. Its more like glass fibres.

Acousting matting is very high density batts or an elastomer of high density. Take a look at a stripped out luxury car one day, and see what they use.

[Doctor Drivel]

Good post. Where these Rockwool batts or the roll?

[Robert Laws]

Exactly, but you must ensure that the new, massive, wall is mechanically decoupled from the existing wall and that flanking paths are filed.

"noise control for residential buildings" by david Harris isbn

0-07-026942-4gives the amount of attenuation you get for all sorts of different constructions.

Robert

[Chris Hodges]

Even heavy foam underlay can make a difference, though not enough in real nuisance situations. Good for PC cases though if you've got noisy _internal_ fans.

Chris

[MJ]

It was around 16 years ago, and as far as I can remember it was roll.

Mike E.

[Doctor Drivel]

A very big difference. The solid bats are reasonably effective, with the thick Fermacell pre-finished plasterboards even better. Fermacell has mass and is like MDF in nature.