[GSBN] SB & Acoustics

Mon Nov 15 19:10:40 UTC 2010

Hi Sarah,

The Sound wall in Nevada was built by Rick Green's Benchmark Development.
and had a concrete tilt up wall on one side.

here is his website.

Tim

p.s. if we don't already have too many rice farmers and if Rick is willing
I'd be willing to lift my personal ban on Nominating more Californians to
this list to Nominate him. He's a good, practicle builder with lots of
perspective that genuinely differs from the "conventional" Straw bale
builder. He grew up and still is a rice and wheat farmer. And does some
manufacturing as well as construction.

On Sun, Nov 14, 2010 at 8:00 AM, martin hammer <mfhammer at pacbell.net> wrote:

>  Hello Sarah,
>
> Some years ago a strawbale highway wall was constructed in the state of
> Nevada.  I’ve seen photographs and text written about it, but I can’t put my
> hands on either, even after doing a moderate internet search.  I did find
> reference to this system of construction being used as an acoustic barrier
> in a Nevada Department of Transportation report.  You can see it via the
> following downloadable link:
>
>
> http://www.nevadadot.com/reports_pubs/Research_Pubs/pdfs/ResearchReports/2001/01_006A_part1C.pdf
>
> On page D-2, “Hay Bales” are described as one of many “Previously Submitted
> Soundwall Systems”.  Further on there is a matrix evaluating the different
> systems according to an array of criteria.
>
> I’ve often thought that strawbale walls would be great acoustic barriers on
> the side of highways.  I don’t know how the Nevada wall has performed and
> weathered, but the challenges for these walls seem to be
>
>    1. that the wall’s height be adequately restrained against lateral
>    loads from wind and earthquakes
>    2. that the bales remain dry enough to avoid deterioration
>
>
> I have seen strawbale landscape walls by others where I know the bales
> rotted (a 10 year old wall with lime-cement plaster) because I did
> conclusive probing, or where I suspect the bales rotted because of a hollow
> sound.  I’ve thought for some time that putting a ventilating “roof” on a
> plastered bale landscape wall would greatly improve its longevity.  Or one
> can simply accept that the bales are just formwork for “structural” plaster
> and let them deteriorate, but that wouldn’t work so well for tall walls or
> acoustic barriers.
>
> The acoustic issues for a highway sound barrier are worth carefully
> considering.  Some were mentioned by Derek and Graeme.  I agree with most of
> their points.  I’ll add a few things.
>
>
>    - Mass is an important element in acoustic barriers, but it attenuates
>    mostly the lower frequencies.  Transmission of higher frequencies can be
>    diminished by less massive materials, such as straw bales.  Here we’re
>    talking about transmission *through* the barrier, not above or around
>    it (as Derek points out).  So extent of the barrier is important.
>
>
>
>    - The surface of the barrier, both its texture and it
>    absorptive/reflective qualities, is important.  So on a straw bale wall, a
>    roughly textured clay plaster finish would absorb more sound, and the sound
>    that was reflected would be more dispersed, as compared with a dense,
>    smooth, cement plaster finish.
>
>
>
>    - There is a difference in acoustic performance between having an
>    acoustic barrier on one side of a highway versus both sides.  Having the
>    barrier on one side creates a worse situation on the side without the
>    barrier, because it imposes additional reflected sound on that side.  Having
>    the barrier on both sides creates back and forth reflectance.  That can make
>    the sound in between the walls (on the highway and its shoulders) rather
>    unpleasant.  Although I suppose we don’t really care (or care much less)
>    about the acoustics on the highway itself.  Having an acoustic barrier on
>    both sides, with back and forth reflectance, can change the acoustic
>    dynamics and the reach of the sound on either side of the highway, because
>    the location and height of the “source” can change as it bounces off the
>    walls.
>
>
> I do think a plastered strawbale wall provides a good balance of mass and
> insulation/absorption (if that’s an accurate way to state it) for an
> acoustic barrier, in a similar way that a plastered strawbale wall provides
> a good balance of mass and insulation for thermal performance.
>
> Those are my thoughts on the subject.
>
> Martin (bouncing off the walls) Hammer
>
>
>
> On 11/11/10 6:42 PM, "Sarah Johnston" <sarahjohnston at ihug.co.nz> wrote:
>
> Hello!
>
> We've had an inquiry from a local road works company about using straw bale
> as a landscape wall for acoustical reasons along the main highway (keep in
> mind, in this neck of the woods...the main north-south road is two lanes
> only...).
>
> They have requested acoustical research and data.  We have the information
> in Bruce's book, but I thought I would check to see if there has been any
> new testing or research done recently that you could share with us?
>
> Does anyone have experience with landscape walls along busy highways?
> I'm questioning the overall long-term durability of this type of landscape
> wall.  Your thoughts and input are all welcome.
>
> Many thanks!
>
> Cheers,
> Sarah
>
> Sarah Johnston
> Sol Design, Ltd.
> 50A Connolly Street
> Geraldine New Zealand
> 03 693 7369
> sarahjohnston at ihug.co.nz
>
>
>
>
>
>
>
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-- 
Tim Owen-Kennedy, Owner
Vital Systems, natural building & design
P O Box 751, Ukiah, CA 95482
www.vitalsystems.net
888.859.6336
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