Timber Flooring underlay performance

[Hub]

Hi everyone

We have created our studio doors using two 25mm thick pieces of MDF board with 2mm thick timber flooring acoustic underlay in between.
The question is, can this same material be used on walls between layers instead of Greenglue? Would the performance be anywhere near greenglue?

Here is a link to the acoustic underlay product.

http://www.dunlopflooring.com.au/reside ... -underlay/

Dunlop Timbermate 1.jpg

Dunlop Timbermate 2.jpg

[Soundman2020]

... acoustic underlay in between. ... The question is, can this same material be used on walls between layers instead of Greenglue? Would the performance be anywhere near greenglue?

Simple answer? No. As their web site says, that stuff is meant only to be "timber flooring underlay specially designed to reduce sound transfer whilst providing added moisture protection": It provides some level of impact noise attenuation, which is very, very different from what Green Glue (GG) does.

Green Glue is a visco-elastic polymer. It is applied in a gooey liquid gel state in a specific manner, and it never hardens: it remains flexible, soft and "plastic" (in the true sense of the word) forever. It acts as a constrained layer damping compound between the two materials, which is a specific type of damping that acts on sheer waves in the panel. It is not designed to be an impact noise attenuator (although it is pretty good at that too).

Impact vibrations and sheer waves are very different things. Impact noise attenuation and constrained layer damping are two very different things.

We have created our studio doors using two 25mm thick pieces of MDF board with 2mm thick timber flooring acoustic underlay in between

The same as above applies to using underlay between door panels: It is designed to attenuate impact noise, not sheer waves caused by airborne sound striking it at random angles. So your door will be good at reducing the sound of people knocking on the door, but not so good at damping the transmission of sound waves through the door.



- Stuart -

[Hub]

Thanks Stuart. I did ask about this in this post

http://www.johnlsayers.com/phpBB2/viewt ... 10&t=18165

You mentioned that it would be alright to use it, so we did. Am I missing something?

[Hub]

Anyone?