[Strawbale]Re: soundproofing tests

[Rene Dalmeijer]

Trevor,

First off compared to normal brick structures SB is better. Good execution 
though is critical but this is of even more importance for bricklaying 
because here any voids between courses will vastly compromise performance. 
Because the plaster layers are just one big homogenic surface integrity is 
much easier to achieve with SB

In 2003 we did an ISO 140-3 Sound proofing test at the TU/Eindhoven 
acoustic lab.

The result of the test boils down to the following 55dB-A (according to A 
weighting)
The test sample was with asymmetrical earth/clay plaster 35mm at sound 
source and 25mm on the other side on 2 string 460mm wide bales. The bales 
had intentionally no further reinforcement like pinning or netting.
What the test means is that a SB wall performs marginally better then a 
traditional cavity brick wall. This is not due to sheer mass, as the SB 
wall is quite a bit lighter, but due to its structure. The SB wall is an 
almost perfect example of a type of acoustic screen consisting of two not 
so stiff membranes surrounding a damped cavity.

Therefore simply extrapolating the mass would give you quite incorrect results.

We hope to do some more tests in the future to be able to extrapolate the 
results of the test we have already executed this will include thicker 
plastering. What I can already say is that if the plaster layer is 
increased to roughly 45mm we expect to reach around 60dBA.

At 07:36 AM 5/3/04, you wrote:
>have there been tests to rate a strawbale house ( with stucco) with regards
>to it's soundproofing? I can get STC ratings for brick homes, but not
>straw.
>I would appreciate knowing if it is on par with Brick homes.
>
>The soundproofing is directly related to mass. What are the average weights
>and dimensions  for bales with stucco. I can figure out a per sqr/ft weight
>and compare .


Rene Dalmeijer