Re: [strawbale] Progress and questions

[Catherine Wanek <blackrange@zianet...>]

At 06:28 PM 7/4/01 +0200, Attila wrote:

        * Does anyone know a machine (or idea of a machine) capable of
          applying earth based plasters on the straw wall beside the human
          hand?

Hi Attila,

Yes, any machine that can pump on a cement stucco can also pump on earth
plasters.   The earth must be finely screened, so stones or
large particles can plug up the pump.  There are a number of types
in the US, from hand-held, to pumps that spray on large volumes.  Of
course, I would look for what is available near you (I saw a hand-held
version working in Denmark last year.)  

I would also recommend The Last Straw, issue #33 on Plasters.  In it
articles discuss pumping on plaster, as well as hand-applied mixes.
For instance, Bill & Athena Steen use very little sand, if any, in
their earthen plasters -- Interior and exterior.  They use a lot of
chopped straw, and I mean a lot -- almost as much as can be mixed
in.  This allows them to apply a very thick first coat, which helps
to even out the wavy bale wall, and produce a more straight wall, which
is preferred by the Mexicans (and many people.)  The straw also acts
to structurally reinforce the plaster.

Earth plaster must still be protected from driving rain, preferably by a
wide roof overhang.

        * What is the fastest and cheapest way to purchase books like
          Serious Straw Bale, or Beauty of Straw Bale Homes? Shall we try
          Amazon, or can we find a European bookstore?

I asked this question of Niko Horster recently and this is his
reply.  I recommend ordering a few at a time, if possible, to get a
discount.

Hi, this is Niko Horster with Chelsea Green. The best way
for you to get our books is through Greenbooks in the UK. Their website
is
www.greenbooks.co.uk
and your contact there is John Elford. I am copying him on this mail as
well so you can emial him directly. 
Thanks and good luck, Niko.

        * Martin: If I remember correctly you are experienced with
          precompressing load bearing walls using baloons. What kind of
          baloon can fit this purpose?

Attila, the "blue balloon" is is a patented system developed in
Canada.  It looks expensive, and like a lot of work to me, and
privately some of the Canadians who have tried it have said the
same.  More simple systems of "pre-compression" have been
developed by the Steens in Mexico, as well as Chris Magwood and Peter
Mack in Canada.  The latest Last Straw (#34 - Good Details) has an
article about the Magwood/Mack system, which is quite simple, low-tech
and cheap.

Personally, I think precompression is useful to a point.  It will help the most to firm up load-bearing walls with soft bales.  However, just putting on the roof will compress the walls.  In Canada, they have a very short building system, and want to get to the stucco (render) before it gets too cold to plaster.
So they precompress, so they can stucco right away.   Of course NO plaster - cement, lime or earth, will tolerate freezing.  It will be ruined, and will need to be replaced.

In a climate with a longer building season, or if you start early in the year, you can put up your walls and roof, and wait for your walls to settle (about a month after the weight of the roof is applied) before plastering.  This is to prevent structural cracks in your plaster.  It is more serious with cement-based stucco than an earthen plaster.  When you have the roof on and get your first really big snow, it's also possible you may experience more settling.

It is also okay to go through a winter without plaster on the bales, without fear of moisture problems, as long as your roof is in place.  However, the bales will not insulate nearly as well, as when they are plastered.  Also, animals may decide that your bale walls are a great place to live, too.    So I DO recommend trying to plaster before winter.

Try to avoid plastering late in the season.  There have been some mold problems with earthen interior plasters applied when the weather was cold and wet.  They could not dry fast enough.  If this happens, however, be wary of adding heat.  If the temperature is cold, the plasters may not dry.  But if you add heat to wet straw, you MAY create a perfect climate for mold to grow.

More than you asked for -- hopefully helpful.

Best regards,
Catherine Wanek, Editor
The Last Straw Journal
The International Journal of Straw Bale & Natural Building
HC66, Box 119
Hillsboro, NM 88042
(505) 895-5400 /fax (505) 895-3326
<thelaststraw@strawhomes...>
http://www.strawhomes.com