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Re: GSBN:Moisture Problem

Paul and all the others,

On Nov 15, 2005, at 01:30, Paul Lacinski wrote:

Last weekend just before the first Dutch SB house tour started at the
IJburg house I managed to do some measurements again. The moisture
levels, besides the wet spot, are down again to normal ie 14-16%.

The wet spot due to the scaffolding splash zone is drying out albeit
very slowly.

We have also had the splash problem from the scaffolding- it's very
easy at the end of a long day to convince yourself that the planks
are just fine where they are, even if they are under the drip line of
the roof.   I'm not so surprised to hear that the moisture level is
rising in that outer zone of your walls; if the plaster is still wet,
the straw may still be absorbing moisture from it.

My limited
experience has been that that outer 30-50mm dries very slowly, and
always experiences the most active cycling, from rain or from

On two projects we tried Tom Rijven's dip method, but it was so messy
and labor-intensive, and made the bales so heavy and the floor so
slippery, that we quit.  But I wonder whether it isn't worth dipping
the exterior face of the bales, because if that outer 30-50mm were
impregnated with clay, I suspect that it would be alot more durable.

I have not built a real big house using this method but did a test wall
during a show and a very small outhouse using the dip method. The dip
layer dried quite rapidly about 1 hour after dipping. We completely
finished the plaster in about 3 hours after stacking the wall (for the
show wall and the smaal out house roughly the same). During both
occasions it was very nice weather although again on both accasoins we
also did have a short shower. I am really a big fan of the method it is
dirty but works very well for the reasons Paul mentions. I would like
to add dipping also removes the need for trimming.

I'd love to see a simulation- if you decide to look into it let me
know if I can pass on any information.  In your project, is the earth
the finish material on the interior?  And if so, doesn't that create
the opposite permeability ratios from what we have been discussing?

Yes earth is the interior plaster and yes it is opposite to what I
would like. A less permeable interior plaster with a more permeable
exterior plaster.

I fully support Dirks request for a more accurate prediction of
damaging moisture levels in organic materials. Is this possibly a Phd
research project? That would be great taking away a serious constraint
to the acceptence of (specifically in Germany) renewable regrowable
building materials. We all know they perform better then the numbers
tell. I wonder how wood fares within these simulations?

Thank you all for the replies.