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Hemp and Lime Plaster on Strawbale

 
Luna Thompson
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Oh wise balers, I've got a baby coming soon and need to build a cozy home before winter. Still in the planning stages and it's almost August! Ah!
No time to do a clay based plaster. No interest in cement.
I am interested in doing a hemp/lime plaster. It seems to be the superior choice but of course, I have no experience. So dear Permies, Please bestow your wisdom.

Would I be ordering Hemp Hurds or fiber??
I can test ratios of hemp to lime but advice is appreciated!
Would this be a suitable plaster for inner and outer walls??

I've been able to find lots of impressive information about Hempcrete but not much about hemp plaster on bales. Anyone doing this? Any help for a total newb is appreciated!
 
Terry Ruth
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I am interested in doing a hemp/lime plaster. It seems to be the superior choice but of course, I have no experience.


My guess is the source of info has no real experience either. I'd be interested in some test (lab or field) that prove this theory hemp-plaster is superior to what? I see good materials and methods that do have the data have been excluded in the OP. Search for a thread "Breathable Walls" and you will find that lime plasters are decent, certain clays are better, hybrids can even be better depending on climate zone I do not see in the OP. The hemp industry especially from Europe imported to America has people believing all kinds of bs sales hype with no proof in America assuming that is where you are from. The chiv (hurd, fiber) has a high silica content(80%) that binds well with the calcium and silica in certain limes, again, I have never seen proof of the strength of the adhesion. Wheat straw (60%) silica is next. I doubt it matters since neither should be used structurally with an average compression strength of around 60 PSI. Both s/b used as mass and insulation and again, I have seen no core sample testing to proof one superior to other. There are too many factors such as mix ratios, chiv length, needing a chemist and biologist, lab just for starters. We do not get high quality chiv from Europe. To assure that one needs a contract with a local farmer and an ability to understand good chiv from bad. Now that certain states can grow hemp, it will begin to develop but it has a long, long, way to go for the building industry. Standards (chiv and binder) are being developed but, it is a slow process that will take years. Builds are popping up for those that know what they are doing or have the $ to take the risk. Manufacturing is starting, along with getting the machinery that is very expensive needed to process the chiv. In a nut shell, nothing a "newb" should be a part of.

Strawbale has issues if not executed right, hemp too, lime too, mixing all needs alot of knowledge one will not get out here. For starters, read several books since it is obvious there is some misleading, then get with an experienced builder or Engineer would be better. Do not beleive everything on the internet or in books unless it is backed by credible data. In addition, NEVER pay a "consultant" or anyone unless you tour builds that have designed or built, see their name on blue prints, talk to owners, etc. Just because they built something is not proof that it performs well, and do not believe the concept "history prooves it right"...to many unknowns most do not track with that theory of evidence.

If such a "superior" product exist please post the name of the lab or entity that ASTM tested and it's moisture, plastic, shrinkage indexes, compression, shear, allowables, installation guide as tested, in comparison to what it is superior to?
 
Luna Thompson
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Alright. Superior is a bad word, just awful. I'm swearing it off right now.

I was referring to the great possibility that hemp;lime plaster may very well be a better option for me right now.

Hemp:lime plaster over other lime plasters offers increased strength, durability, faster curing time, faster and easier to work with because it goes on thicker and has minimal shrinkage.

I found this link rather encouraging. It covers the many benefits of hemp:lime plaster and mentions it's use on straw bales.
http://thenaturalbuildingcentre.co.uk/lime/wp-content/uploads/2013/05/10226_Ty-Mawr_lime_hemp.pdf

It is from a UK company but I have found some local-ish sources for USA grown hurds at what seems to be reasonable prices.
Completely local and freee clay based plaster would be great hefty thermal mass, if only I could figure out a way to process it in a timely fashion. I'm excited about this other option and so grateful to have ye permies to discuss it with before any decisions or purchases are made.

Thanks for advice!
 
Jay C. White Cloud
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Hello Luna,

I have noted a few of your posts, and they seem to "overlap" quite a bit in information about a pending project of yours that, for all accounts, would just fall under..."Natural Building."

If I may suggest perhaps, for sake of clarity and conciseness, that a post be started about this project, and questions placed there. That way all the information is in one place. In the meantime, I will do my best to assist and answer your questions as I am able....

I was referring to the great possibility that hemp;lime plaster may very well be a better option for me right now.


As for a "better option," comparatively it isn't, and I suspect it really never will be for some time to come in most applications unless it becomes a very "commercial enterprise." I like "hemp products" and those that exist are very nice...They aren't necessarily superior to other modalities. When anything has to be "shipped" to a project site in looses some "sustainability" value and cost the project money. Now I fully understand that many things have to be "shipped or brought in" like the lime itself, nevertheless there are many other comparatives to a buildings "means, methods and materials" that may need evaluation.

So yes...hemp fiber is wonderful...but compared to other available fibers currently, perhaps not the "best option" at all. As Terry has elluded to, there needs to be considerable research before considering "best option" as we don't even understand the..."the interstitial durability of alkali exposure to hemp fiber over time within lime matrix material applications,"...as just one of the "technical aspects" to be evaluated as a comparative. Would I use hemp fiber if available? Yes, but with full awareness of many other comparable and applicable factors...

Hemp:lime plaster over other lime plasters offers increased strength, durability, faster curing time, faster and easier to work with because it goes on thicker and has minimal shrinkage.


I understand this as a "statement," and would have to consider the source information material about such a "strong statement," as it seems to be declared as more "fact" than "comparative assumption." Is the source information for such a statement coming from 3rd party verified or peer mentored scientific research? Is it perhaps coming from the views of a very experience "traditional builder," with decades of experience in many traditional/natural design/building modalities, or is this information coming from a generic source that either has limited "traditional building experience" and/or "strong views" about the "positives of hemp?"

Statements about a material like "Hemp fiber" (or any other modality) must be thoroughly vetted before fully accepting or understanding the means, method or material.

I found this link rather encouraging. It covers the many benefits of hemp:lime plaster and mentions it's use on straw bales.
http://thenaturalbuildingcentre.co.uk/lime/wp-content/uploads/2013/05/10226_Ty-Mawr_lime_hemp.pdf


And this kind of makes my point...I like this "company" a great deal and reference there information, but fully understand..."they are SELLING SOMETHING," be it a product of theirs directly or a modality that they make money from...This does not devalue the information, but warns me to examine other sources as well as a more "balanced perspective."

I think lime is wonderful...I think hemp fiber is wonderful...Nevertheless, the two materials together may only be of average value comparatively to other combinations for a specific project...

It is from a UK company but I have found some local-ish sources for USA grown hurds at what seems to be reasonable prices.


That is great!! Now we can use this "pricing matrix" as part of the comparative to other available systems to a given project and it location...

Completely local and freee clay based plaster would be great hefty thermal mass, if only I could figure out a way to process it in a timely fashion. I'm excited about this other option and so grateful to have ye permies to discuss it with before any decisions or purchases are made.


And we are pleased to assist! as well as help vet out perhaps the "best options" for your pending project...

Regards,

j
 
Terry Ruth
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The best advice I could give anyone thinking of building with strawbale is to follow code if the local Building and Safety office allows it. A PE will not be required that can cut substantial cost since the 2015 International Building code has been developed by many of those and field or empirical evidence. If they reject the SB code a PE will be required and there still may be local jurisdiction requirements the PE cannot over write since the PE only handles the structure analysis and may require an Architect for Energy codes, etc.... It has several types of plasters that have to meet requirements, additives such as hemp can be added per "AR104.4.3.6 Plaster Additives", that will require proof testing(again if the inspector accepts it). There is nothing fast drying about these wet install methods, in most cases windows and doors have to be left off to allow moisture contents to drop below 20% based on a meter test the inspector checks, same test on random bales. If in high humidity that can be a long time, three months min although some binder makers are trying to get it down to 1 month or two weeks. Braced wall lines, mesh, are also required for racking and shear depending on seismic and wind zone. If it all looks like Chinese hire an "experienced" Architect and/or GC, a state licensed one familiar with the local environment to help execute the build. All materials can be sourced locally or regionally, try and keep the embodied energy down is all one can do, forget shipping from Europe to the USA that is not "natural"....I recommend staying away from hemp until such code exist, there is no approved material substitution for it in this code. Now that some states are growing hemp, the American binder industry is developing fast to make some $$ using lots of junk fillers to profit. Big lime manufactures are already all over it so they should be available at local lumber yards in the next five years or so for around $50-100, 50-90 lb bags. You can DIY binders when the shiv is more available, that should be taken to a lab. I have test blocks that have been in my environment for about 1 year that are heading there soon. We may also offer a binder sooner or later, or as soon as the chiv machinery to separate the chiv from the stalk is available in the states and the bugs worked out. One could do this by hand. The bags and labels, insurance, will cost me more than the binder materials IF I decide to market. DO not be mislead by sales hype, there is ALOT to know here.

This simplifies matters but there are some weeding out of code choices one needs to know. If you have questions ask, this is where you focus and ask questions about real data, to get a permit and past inspections, not personal or internet sales hype quoted.

http://www.strawbale.com/wp-content/uploads/IRC_StrawbaleConstructionAppendix_Approved_10.4.13r2.pdf

Good luck with build and baby Glad mines 25. You have to be careful but on the right track to create a healthy infant home. It will be a big challenge to get it designed and built properly before winter.

 
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