[Strawbale] Futility of quantifying properties of natural materials (was Re: compressing or not
archilogic at yahoo.ca
Wed Mar 12 18:57:58 CET 2014
On Wed, 12 Mar 2014 06:27:43 -0400, permacultura la boa
<casadipaglia at hotmail.com> wrote:
> Tests many times are contradictory and often fail when they want to put
> natural materials into a table...
I have to disagree with Stefano's statement (above) because it implies
that the properties of natural materials cannot be quantified to any
While it is true that often, testing will yield different values for the
same properties of the same natural material, one understands that it is
due to the fact that natural materials aren't produced in a factory where
quality control procedures would ensure a degree of uniformity.
However, so long as the testing procedure is well-defined and the
characteristics of the samples being tested are properly measured and
identified alongside the test results data, the properties of natural
materials can be put into charts and tables that will provide accurate
information that can be useful for the purposes of design and analysis.
As an example, I would simply point to Dr. Minke's table that lists the
thermal conductivity values for wide range of different densities of
Without such testing and accompanying data, we would see much more of the
nonsensical mythology that often surrounds natural materials which, when
taken to heart by natural building novices, more often than not, leads to
disappointment and/or poorly-performing buildings and/or building failures
when those myths confront the real world.
As to the question of whether or not to pre-compress non-loadbearing SB
walls, I would argue that precompression is always beneficial from a
If the tensile elements used to provide the precompression are properly
attached to the frame & foundation, even non-loadbearing SB wall panels
can provide substantial, useful resistance to live loads and that only
helps to improve the serviceabilty and durability of the building overall.
=== * ===
Rob Tom AOD257
Kanata, Ontario, Canada
< A r c h i L o g i c at Y a h o o dot c a >
(manually winnow the chaff from my edress if you hit "reply")
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