[GSBN] Sound transmission through s/able walls

[Derek Stearns Roff]

Thanks, EJ.  Your questions bring to mind a few more.  What is the source and character of the noise of concern?  How will sound be blocked in the ceiling and through doors and windows?  Windows, especially, will transmit much more sound than a plastered strawbale wall.  How will ventilation be dealt with?  Free air movement is needed for a healthy house, but it freely transmits sound.

The wall’s performance will depend in part on good detailing.  The gaps between the bales will transmit more sound than the center of the bale, so great care in stuffing would yield benefits.  The transitions at the base and top of the walls, and at all openings, also requires careful attention.  Uncoupled mass is a big part of sound attenuation, which plastered bales already do well.  Additional layers of decoupled materials, such as the cellulose insulation layer and siding that Deva and some of the Vermonters are using, would improve sound attenuation.

Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


On Oct 20, 2015, at 8:39 PM, ejgeorge at riseup.net<mailto:ejgeorge at riseup.net> wrote:

ch 8 of Bruce King (et al)'s Design of Straw Bale Buildings (with Rene' Dalmeijer) covers acoustics and references several tests from  1995-2003 suggesting very good but not soundproof performance:

Straw bale wall with ~ 1 inch of plaster per side rated a Sound Transmission Class of ~ 55;
an STC of 50 is listed as some very loud sounds can be faintly heard and STC of 60 or higher is considered essentially soundproof.


I think most people find them pretty quiet - have they visited/stayed in any to get an idea?

One question is
Are they looking to build with strawbale for the primary purpose of having it provide a soundproof/nearly soundproof house? In which case other building methods might provide equivalent or better acoustic control, possibly more affordably.
or
Are they looking to build with strawbale for primarily other reasons and are worried that it won't quite be up to their ideal level of acoustics as well? In which case they might consult with an acoustical engineer on ways to improve in any room(s) they feel it is particularly crucial.


Good luck!

ej




On 2015-10-20 21:05, Graeme North wrote:
Hi Folks,
I have a client with extreme hearing sensitivity, who is very
concerned about the possibility of hearing sound coming through
strawbale walls.
Does anyone know of any sound attenuation tests that have been done on
s/bale walls please, and what the results are?
(and I hope that you are all planning on coming to New Zealand for the
ISBC16 next March so that we can meet in person)
Thanks
Graeme
Graeme North Architects
49 Matthew Road
RD1
Warkworth 0981
New Zealand
www.ecodesign.co.nz<http://www.ecodesign.co.nz>
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