Re: moisture measurement

[dneeley@ccsi.com (David B. Neeley)]

Hi, everyone. I have greatly enjoyed reading this list regularly,
particularly since I'm planning to build a SB house this summer. The
discussion about humidity in straw walls is of acute interest, given that
Austin is frequently fairly humid.

A simple question about the methods of measuring moisture content in the
walls...as several of you have pointed out, the conductivity of water
changes dramatically as the content of the water changes...that is, as it
becomes less pure.

Several have postulated that you can simply measure the conductivity of
"moistureless straw" and the conductivity of rain water, then factor them
together to estimate moisture content.

Perhaps I'm missing something...what about the fact that water is the
"universal solvent" as the high school science classes point out, and that
it will not be in the bale wall without dissolving quite a bit of material,
thus changing its conductivity rather dramatically.

Then again, what is the conductivity of the water from sources other than
rain? Such as, perhaps, evaporation? And what is the percentage of moisture
in the walls from these interior sources compared to rain water?

Please understand, I'm likely not as advanced on most of these topics as
most (or maybe any) of you that are working through the problem...but if I'm
missing something then I'm certainly unclear on the concept. I would
appreciate it if you might enlighten me in these areas.