[GSBN] Maximum Density for straw insulation

Rene Dalmeijer rene.dalmeijer at hetnet.nl
Tue Oct 4 06:40:47 CDT 2016


Rikki,

I see nobody is reacting to your mail. I have not been doing any testing myself but as far as I have been able to determine on the tests I have seen, it is almost impossible to compress strawbales sufficiently to decrease the effective insulation value. One of the reasons for this is that in thicker samples some convection takes place in the cavity with open cell insulation like straw bales. This means in many cases increasing the density improves the effective insulation value to some extent. As far as I am aware how much variation has not been determined conclusively as there are too many variables influencing insulation values for hole wall systems. What I dare to venture to say this variation is not significant given a building grade 115kg/m3 straw bale giving an R Value of 5-6 (metric, 28-34 imperial) for the finished wall. (but as you know this is debatable)

Snug in some warm bales (R 5-6) in the reclaimed swamp at the mouth of the Rhine
Rene Dalmeijer

On Sep 13, 2016, at 12:10, Rikki Nitzkin wrote:

> Hi everyone, 
> 
> Recently returned from our national gathering, I have a question about thermal transmission testing….
> 
> There was a debate going on at our event about what is the “best” density for a bale, referring to insulation (not structural) is.
> 
> Some people were under the impression that “the denser the better” and others that an “overly” dense bale will insulate less, as the fibers of straw would be crushed and retain less air - therefore insulating less.
> 
> Has anyone tested this? Is there data anywhere on what the Maximum or Minimum Density would be for best insulation?
> 
> thanks, Rikki
> 
> 
> Rikki Nitzkin
> Strawbale Building and Clay Plaster:
> education, consulting, and building
> www.rikkinitzkin.worpress.com
> https://www.facebook.com/TallerConCo
> 
> tallerconco at gmail.com
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