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16482Re: [SB-r-us] earth plaster books

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  • mvankanan
    May 30, 2014
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      Hi Nick


      Thanks so much for the post, I'm busy too right now but I want to thank you, there's so much to think about in it. It will take me awhile to go over all of it.


      I'm guessing from the time stamp that you are in Europe, I'm not sure if I'm familiar with lime plaster, but maybe. I'm sure familiar with the old 3 coat plaster over lathe, used in the states before sheet rock. I think that might have been lime? It used horse hair for fiber and was pretty sandy, which you didn't notice till you found some that failed. It seemed like the sand would separate and easily brush off the lathe.


      I would dense pack the walls if I was going to use cellulose in them. One of my big questions is how much? 12" of dense pack in some kind of double wall system was kind of the standard in the north east. It was supposed to be virtually air tight. I believe that air tightness won't be a factor in either plaster type per building sciences article on straw bale  ( by John Strube ?)


       12" of dense pack was also supposed to be able to store a lot of water vapor and release it back out. If the walls could dry it was supposed to be ok. 12" of dense pack is much more than I would need by just energy calculations, the house will be in southern Mo. I wondered if it might not make sense to just pay for the additional cellulose and let it deal with the moisture moving in and out the wall and letting it dry through the plaster. Of course you would do whatever to try to eliminate moisture sources. In my case this structure will be built more like a guest house, most cooking and bathing would be outside or in a semi-permanent structure at least at first.    


      Does your plaster touch the cellulose? That's the other question, in the straw bale article it mentioned that the straw by its nature wasn't prone to wicking water towards the interior. I wasn't sure if I should try to have some kind of barrier here, felt/tar paper? Maybe one side? Which one? 


      I need to also find out if summer time humidity would be a problem?  


      Sounds like you sweat the small stuff too? I'm an older former carpenter who always tried to install air and vapor barriers perfect. Lost a bit of money doing it too!  Kept doing it, guess I'm not that smart. That 12" of dense pack was supposed to eliminate those concerns? Wasn’t an option for you though?


      I’ll be returning to Mo in July, I’m anxious to see my little wall. I did notice that the earth plaster peeled off the wood where it was thin. I never barked the wattle I applied it to, I thought that might be it, but thought that it might be that that part just dried to fast. I will hopefully have been able to read up on and perform some tests. I think that the clay here is pretty pure. How would you test the clay? How did you chop your straw?


      I’m also considering 12” of sawdust or straw slip, some kind of slip, could you use pine needles? This house will be built on leased land, without permits. I want to build it as cheap as I can, sawdust will outlive me by far. I thought that perhaps the cellulose with all the combined benefits might be worth it, I didn’t price it out yet; I have to do my attic in my current house I roughly figured it to about $1000 dollars. That should be enough to cover 3 sides and the roof 12” walls 16” roof, the south side will more likely be covered by some type of sunspace. Over insulated, but not that big of a cost savings, if there was any added benefit, I thought. I could always use the money for something else though.


      And hours after dashing off this quick post……………. back to work ripping 10 sheets of delaminated ply wall off a wall, where the carpenters didn’t sweat the small stuff.


      Thanks again Nick



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