Seen this in a new Cinema construction, got a question...

[jonsay]

I am in the process of designing my own home cinema/music room and while working on a local construction site encounted this floor system to prevent sound from the cinema room passing to the rooms underneath.

It seems to be 2 layers of 18mm birch plywood with a layer of 15mm knauf soundboard.

Will the gaps effect the effectiveness of this flooring to prevent sound transmission, or is the mass of the flooring more than enough to prevent said transmission. Any help is gratefully received. Thanks!

[gullfo]

it's certainly a part of the solution - however, that amount of mass by itself will not stop LF - which is something home theaters tend to produce a lot of.

[jonsay]

it's certainly a part of the solution - however, that amount of mass by itself will not stop LF - which is something home theaters tend to produce a lot of.

If an increase in mass would help, approximately what kg/m2 should I be aiming for? As I understand the knauf board is around 18kg/m2 for 15mm thick and the 18mm plywood would be around 8kg/m2 giving a total of 34kg/m2

[DanDan]

Bass is huge in every way. Waves up to 10M long. 10dB more energy in the bottom octave than in the top...... It is very difficult to stop or hinder.

[gullfo]

2x the knauf board with green glue would be more effective than the 2x ply + knauf. and that mass needs to be decoupled from the other mass layer so there is no structural transfer.

[jonsay]

Thanks guys for the info. I have actually got my hands on some proper sound rubber pads so I can physically seperate the room from the surrounding structure.

Thinking room in a room is the best option so I'll plan it that way.