How much insulation between joists to prevent/reduce sound?

[pudzer]

There are many other threads on sound and/or insulation but non answer my specific query:

What is a good amount of insulation to put between the joists in a standard ground floor ceiling (not concrete) to minimise noise as much as possible?

My builder providers suggest 150mm of fibre glass (they say that acoustically it does the exact same job as rockwool but it is much cheaper).

i have put in this option now but am concerned that it's not enough. I have slabbed over it also so not an option to remove slabs.

Thanks

 

[wexford dude]

Hi Pudzer,

The insulation between the joists may stiffle but will not completely get rid of the noise of someone walking across the floor.
The insulation will help reduce general first floor noise such as music etc.
Is it too late to lay a noise proof membrane on top of the joists.This will cost a bit but anyone I know with a young family would gladly bear the cost of concrete floors to avoid the general noise caused by walking, rocking beds etc.

Hope this helps,
Wexford dude

 

[Satan's Bed]

Rockwool will help absorb airborne sound.
Impact sound (footfall) is combatted by isolating your floor from the surrounding structure - in effect you are "tanking the room for sound". This means you lay your membrane on the floor and bring it up the wall to the height of your finished floor surface and out under the skirting board.

S.B.

 

[builder ed]

Some of the timber frame companies offer an acoustis strip (about 5mm) which is laid over the joists before putting the OSB flooring. This helps to deaden the sounds being transmitted from upstairs.