[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
GSBN: Re: STC of Straw bales
- To: GSBN GSBN@..., Coralie & Andre de Bouter m.ep@...
- Subject: GSBN: Re: STC of Straw bales
- From: Derek Roff derek@...
- Date: Wed, 16 Oct 2002 14:59:34 -0600
- Reply-to: "GSBN" GSBN@...
- Sender: "GSBN" GSBN@...
--On Wednesday, October 16, 2002 10:47 AM +0200 Coralie & Andre de
Bouter m.ep@... wrote:
In France there is a vicous rumour going arround that SB walls are
a poor sound insulator. Arnaud Cauwel wrote a report for his school
of architecture in which he claimed that straw (because of its low
mass) insulates poorly. No numbers or test data is given.
This is like saying birds can't fly because they don't have feathers:
wrong data, wrong theory. While straw bales are not terribly dense,
they do contain substantial mass. A plastered strawbale wall will
have about half the weight/mass of an adobe or stone wall in an
equivalent structure (per square foot/meter of wall surface, or per
lineal foot/meter of a wall of the same height). A plastered
strawbale wall will weigh more than twice what a brick wall weighs.
There is a great deal of mass there.
In attenuating sound, mass is important. However, thickness also
matters. The same amount of mass will cut the sound more if it is
deployed at lower density, in greater thickness. Rigid, elastic
materials (like steel) will transmit sound more effectively than
softer materials with multiple internal planes of reflection, like
foams. Strawbale walls score well on all three counts: high mass,
great thickness, and soft, amorphous material.
Hard plasters do lead to echoes, so the inside of a SB house may not
be the perfect environment for a musical recital. The non-strawbale
parts of a structure, such as roof, windows and floor, can have a
significant influence on sound performance. But if other things are
equal, a SB house will have sound insulation properties superior to
most common building materials, and on par with the best.
Still, our French SB friends have a problem. It's often hard to
fight stupidity and prejudice with numbers or logic. The people who
are willing to spend a few minutes in a SB house will be convinced.
Language Learning Center, Ortega Hall Rm 129, University of New Mexico
Albuquerque, NM 87131 505/277-7368 fax 505/277-3885