[Strawbale] certification of straw bales

Dave Howorth dave at howorth.org.uk
Wed Mar 6 15:49:54 CET 2013

On Wed, 2013-03-06 at 15:17 +0100, asbn wrote:
> There seemed to be a problem with the server, as Jenik (Jan Hollan)
> told me, so I send this answer again to this list.
> Sorry, if you got it twice...)
> Dear Caroline and all the other balers on this list
> I just talked to Dr. Mikulitsch from OIB, the Austrian Institute of
> Construction Engineering.
> As far as I understood, the situation is as follows:
> * If there is an ETA (European Technical Approval) for a building
> product (like a certain building straw bale, tested in 1 country),
> this building product can be used in each European country, with a
> (there are just 2 exceptions: Germany and France, where usage purposes
> are defined,
> so maybe you have to get a national approval for the usage of these
> products additionally in these 2 countries).
> The problem: building products are defined by 1 (or more)
> manufacturer(s), a manufacturing process and a quality management.
> So, in case of the approved (ETA) Waldland straw bales, it is possible
> to build with these straw bales manufactured in Lower Austria
> everywhere in Europe, with the same characteristics and attributes
> (lamda, fire-safety,...).

I think this illustrates the difficulty with using natural products in a
regimented system. They are not all the same.

Timber is a natural product (mostly :) but the market is so large and
well-established that it makes sense to have a European system of
grading individual timbers so they can be interchangeable. But there are
still oak-framed buildings that exploit the properties of individual
pieces of timber.

I do think there is a useful parallel with lime, for example. There are
multinational companies that make various products from lime and you can
buy one of these products and rely on their certificate for various
properties of the product. But you can equally buy some unslaked lime
(or even dig it up and burn it yourself) and slake it to make your own
putty. That putty does not have a certificate, but in the UK at least
you are free to use it. The difference is that you have nobody to sue if
its properties are in some way unsuitable for your application.

The same with sheeps wool. You can buy processed products, or you can
shear your own sheep and treat it with borax or not as you wish. In the
latter case you carry your own risk. In the former case, you can sue but
as has been proven in the past, this may not be a satisfactory remedy.

So it is with bales. But the market is much smaller and less mature. In
most cases bales are purchased directly from a farmer, perhaps via a
merchant and/or broker. Quality depends on the knowledge and care of the
farmer and the buyer and knowledge of the chain of custody. Risk sits
with the buyer and builder.

I was talking yesterday to a warranty provider (another way of
quantifying and transferring risk). He won't warrant straw bale
buildings. But the problem isn't the bales themselves, it is how the
detailing of waterproofing can be proven. And in the most advanced case
they investigated for a pre-fab bale system, it was the airtightness
detailing between the timber frame of the pre-fabricated units that was
the showstopper. Fortunately, other providers will consider warranties.

> There are just two ways to get a RIGHT (and not just an approval in
> individual case) to use these bales by undefined manufacturers is:
> 1) the certification of straw bales, manufactured by different
> farmers, certified as a building product by a recognized certification
> authority
> 2) or a national or European NORM (Building Code).

It doesn't make any sense to expect to have a RIGHT to use bales from an
unknown origin, unless you also accept the OBLIGATION of the risks that
are carried.

I think there may be another issue tied up with the word 'code', which
is a word that I find offensive in this usage. To me it is associated
with prescriptive systems of regulation, where there must be a
description of some material or technique in the 'code' before you are
allowed to use it.

I prefer 'building regulations' that do not specify what you are allowed
to do but instead state basic properties of the building that you
construct. The building must not fall down, even when it rains. The
building must not fall down if it catches fire unitl half-an-hour has
passed. Etc etc. It's up to you to demonstrate that you have met those

JMHO, Dave

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