Sound proofing - 'sand plugging' vs acoustic mineral wool?

[justanotherguy]

I live in an upper floor maisonette, and while refurbing, this is a great time to install sound proofing. I was all set to go for acoustic mineral wool + acoustic plaster board in between the joists, but just recently saw something called 'sand plugging' mentioned in Collins DIY manual.

My joists are very substanstial, very deep and wide, so I'm sure it could take the weight. In fact, where I took away the kitchen, three of the spaces between joists was completely filled with old concrete.

I also read that 5 or so centimetres of dry sand represents a far greater mass than anything acoustic wool could add, and that mass is the key factor for stopping airborne noise, particularly lower frequencies.

So, my plan is to attach battons about 2 cm above the plasterboard ceiling of the flat below, then nail acoustic plasterboard to those, then 5cm of sand spread over that, and then another layer of acoustic plasterboard, attached to more batons, and sealed across the edge.

Ideas/suggestions welcomed.

Thanks

Marcos

 

[MisterE]

I've seen sand used as an in-fill in a ground floor stud wall, to soundproof a home studio, but never heard of it used to separate ground and first floor apartments...

Could work, I suppose. I'd want to be very certain that the structure can take the extra weight, if I were you... what's the total floor area that you're going to cover??

 

[justanotherguy]

It's a huge open plan room - 11m x 4m = 44 m^2

The floor joists are each 10cm x 18cm, and 30 cm centres, one end supported by internal party wall, the other by external outer wall.

EDIT - Actually, thinking about it, I think the weight should be fine.

Say I have 5cm of sand spread evenly across that area. That's a total volume of sand of 0.05 x 44 = 2.2 cubic metres.

Taking a value of 1.5 tonnes per cubic metre, that's 3.3 tonnes spread evenly.

Taking a value of 70kg as the weight of an average person, that's about 1500 / 70 = 21 people.

I very much doubt even having 50 people in the flat would be an issue, paticularly given the substantial joists they used in the good old days..

Let me know if my basic calcs are utterlly crazy!

Marcos

 

[holmslaw]

It's not 'plugging', its called 'pugging' , used to be installed in top quality houses.

It consisted of 20mm boards fixed between joists about 100mm from top of joist. They would then spread the pugging about 50mm thick, it was like a plaster mix, it dried to a solid but crumbly finish that can easily be broken with your fingers.

 

[justanotherguy]

It's not 'plugging', its called 'pugging' , used to be installed in top quality houses.

It consisted of 20mm boards fixed between joists about 100mm from top of joist. They would then spread the pugging about 50mm thick, it was like a plaster mix, it dried to a solid but crumbly finish that can easily be broken with your fingers.

Thanks for info - was this 'plaster mix' of similar density to sand? Do you think my weight calcs are ok?