Soundproof Wall for Recording Studio - Sand?

[Matt]

Hi ,

I recently had a client propose building a double stud wall and
filling the cavity with sand in order to minimize sound transmission.
The application is for a small recording studio. Has anyone heard of
something like this before? If so, do you have any comments on the
feasibility or effectiveness as compared with other solutions?

Thanks,

Matt

[Tony]

Post by Matt
I recently had a client propose building a double stud wall and
filling the cavity with sand in order to minimize sound transmission.
The application is for a small recording studio. Has anyone heard of
something like this before? If so, do you have any comments on the
feasibility or effectiveness as compared with other solutions?

Yes, there was a company making prefabricated studios in the UK that used to
do this. It works well as the wall is very highly damped. However to get
enough insulation you normally need a double partition. So unless one of
the partition leaves already exists you will need two walls, possibly each
filled with sand. Things to watch: The sand must be very dry. Protect
against any conceivable water leaks as the sand will become extremely heavy
if wet. The sand exerts great pressure at the bottom of the partition as it
partly acts like a fluid, so the partition must be strongly built. I have
also seen (and measured) sand filled doors. They can be very good, but
again really solid construction is essential.

As regards feasibility, it is a non-standard solution that builders will not
be used to so the costs will go up. But, weight for weight, it will be
better than a block wall.

Tony Woolf
www.tonywoolf.co.uk

[Matt]

Post by Tony
Yes, there was a company making prefabricated studios in the UK that used to
do this. It works well as the wall is very highly damped.  However to get
enough insulation you normally need a double partition.  So unless one of
the partition leaves already exists you will need two walls, possibly each
filled with sand.

Tony,

Thanks for the response, I appreciate the information. I have looked
around online but haven't found much - do you know where I might find
more info on this subject? Do you know what STC was measured for this
construction?

Matt

[jerry]

Post by Tony
Yes, there was a company making prefabricated studios in the UK that used to
do this. It works well as the wall is very highly damped.  However to get
enough insulation you normally need a double partition.  So unless one of
the partition leaves already exists you will need two walls, possibly each
filled with sand.

Tony,
Thanks for the response, I appreciate the information.  I have looked
around online but haven't found much - do you know where I might find
more info on this subject?  Do you know what STC was measured for this
construction?
Matt

I'd suspect the STC would not be as good as other approaches such as
hanging the covering wall from rubber isolators at 1000-5000 Hz
frequencies, due to the direct connection of sand between leaves.
Double-layer rubber isolated sheetrock can attain STC's of 60 at those
frequencies, at which point flanking sound transmission paths such as
the floor are as much of a problem as the wall itself. See, e.g.
www.soundisolationcompany.com/sound-solutions/walls/barrier/
Sand probably can't be beat for low frequencies though.

Jerry

[Tony]

Post by jerry
I'd suspect the STC would not be as good as other approaches such as
hanging the covering wall from rubber isolators at 1000-5000 Hz
frequencies, due to the direct connection of sand between leaves.

Double layer and sand are not alternatives. I said you will need two walls,
i.e. a double layer. But one or both could be sand filled. The advantage
comes at the lower frequencies because sand combines high weight with very
high damping. In reply to Matt, I don't have specific info but I do
remember that the constructions worked very well for their weight, as you
would expect.
Tony Woolf
www.tonywoolf.co.uk