[GSBN] Plaster thoughts

[Tim Owen-Kennedy]

Thank you all for your thoughts.

Obviously this is a way more complex problem than can respectfully be
solved, or even thoroughly discussed, over email. I'm really aware of most
of the challenges - chemistry, climate, mechanical. but I've also had lot's
of success with lime over earth and lime in earth. And have invested a lot
of time in understanding why it's successful sometimes and not others.
Hopefully this process will yield more understanding of failure modes at
least and has more potential to find a successful way to meld the modern
desire for cement finishes and the value of preserving traditional
structures. At the very least a whole new group of concerned cement geeks
(and I say that with the utmost affection) now have a much deeper
understanding of the value of earth and lime, and the challenges of cement
and especially how they work or don't work together.

Our primary goals are to match a super flexible, durable, and vapor
permeable top coat that won't easily delaminate on the traditional wood and
earth walls in Kenya. Most likely through the right mix design of a good
intermediary material as well as the the design of the top coat itself.

I'm still much more a fan of an earthen solution. But the PR problem of
Earthen Building as an antiquated high maintenance peasant material is one
that I don't have the skills or funds to over come quickly. So if we can
find a way to have earthen structures experienced as modern by giving them
a functional modern "skin", Then we can save a lot of great existing
natural buildings from being replaced by buildings with huge ecological
footprints. And may even encourage some doubters in the conventional
building world to wade slowly into our Deep Green waters.

Until then, please feel free to share your wisdom and experience as you
have time and desire. It is always welcome and helpful.



Tim

I delivered the first four test panels yesterday. so hopefully we'll be
able to keep you posted soon.

On Mon, Mar 12, 2012 at 8:36 PM, Rikki Nitzkin
<rikkinitzkin at earthlink.net>wrote:

> hi,
>
> I agree with alex's comments 1 and 2, but I would be careful about 3.
>
> I know that using oil as paint makes the house water-proof, but also
> (almost) unbreathable.
>
> If you live in a place as dry as Alex (Didn't you say it rains once every
> 10 years?) it is so dry that there is almost no humidity to be trapped in
> the walls... but in many other places it could be a problem.
>
> As for lime over clay, sometimes it works, sometimes it doesnt. I find
> that Mixing lime with clay is often enough (between 1/6 to 1/2 parts lime
> depending on the type of lime and quality of clay). And if it is not
> enough, you can always add a lime plaster on top. It will stick better if
> there is a bit of lime in the coat below.
>
> Even so, I avoid the use of lime. I would add cow or horse excrement to
> the finish plaster, and/or wheat paste, or even a SMALL amount of oil (no
> more than 4% in volume)... and make the mix plenty of time before you use
> it so it ferments. The fermentation helps a lot. That is usually enough if
> there isn't a lot of wind-driven rain or hail (which seems unlikely in
> Kenya).
>
> good luck, rikki
>
> -----Original Message-----
> From: "Alex Cicelsky (Kibbutz Lotan)" **
> Sent: Mar 4, 2012 12:44 AM
> To: Global Straw Building Network **
> Subject: Re: [GSBN] Plaster thoughts
>
> **************** ** ********** ** ** ****************************
>
> Dear Bruce, Tim and Mark,****
>
> ** **
>
> Three points:****
>
> 1. Not knowing what the climate is there (in particular humidity), type of
> sand (silicate or crushed lime) or clay mineral type, I can only share the
> if it’s dry and the sand is silicate then my experience is that lime washes
> and thin lime plasters will peel off after the first rains.  I’ve seen even
> small amounts of cement cause good clay bricks to disintegrate - I assume
> because of the type of clay mineral.  I hope that’s not what you’re finding.
> ****
>
> 2. For many years we mixed our earth plasters using clay (from dried flood
> deposits and well drilling tailings), course - sharp sands (no fines - wind
> eroded Nubian sandstones quarried from sand dunes) and paper fibers -
> newspaper, egg crates and cardboards soaked for 24 hours+ and broken down
> in a cement mixer.  These mud-paper plastered structures, pseudo
> ‘earthship’ - tires filled with plastic waste, have stood for 20 years with
> very little cracking and an amazing ability to get wet and dry out without
> disintegrating.****
>
> 3. the exterior coating that we like best is used cooking oil using the
> ancient Steen 4 coat recipe: 100% oil (applied heavily with rollers), 75%
> oil + 25% turpentine, 50-50 and finally diluted to 25% oil with 75%
> turpentine.  We apply them one after another without waiting, best when
> it’s hot and Always after the clay/sand plaster is completely bone dry.  *
> ***
>
> ** **
>
> We’ve found that maxing the sand  component in a final, thin plaster coat
> without straw creates the hardest protective layer - that’s particularly
> appropriate where people (kids) come in contact with the wall / bench
> (otherwise they pick at the straw).****
>
> ** **
>
> Good fortune and feel free to drop in since you’re already on the
> continent.****
>
> Alex ****
>
> ** **
>
> Alex Cicelsky ~ Director of Research and Development ~ Center for Creative
> Ecology ~ www.kibbutzlotan.com/ga ****
>
> Kibbutz Lotan ~ D.N. Eilot 88855 Israel ~ Tel: +972-(0)54-979-9009 ~
> Email: alex at klotan.co.il ****
>
> ** **
>
> *Have an iphone/ipod/ipad and want to ‘green’ your home and lifestyle?
> Download the Free Eco Guide App **www.tinyurl.com/ecoguideapp*<http://www.tinyurl.com/ecoguideapp>
> * *
>
> ** **
>
> [image: cid:image005.jpg at 01CC9FA1.4F11F630]<http://www.youtube.com/user/KibbutzLotan>
>  [image: cid:image006.jpg at 01CC9FA1.4F11F630]<http://www.facebook.com/lotan.ga>
> [image: cid:image007.jpg at 01CC9FA1.4F11F630] <http://www.kibbutzlotan.com/>
>  [image: cid:image008.jpg at 01CC9FA1.4F11F630]<http://www.kibbutzlotan.com/ga>
> [image: Eco Guide Black.tif]<http://itunes.apple.com/us/app/eco-guide/id478672397?ls=1&mt=8>
> ****
>
> ** **
>
> *From:* GSBN-bounces at sustainablesources.com [mailto:
> GSBN-bounces at sustainablesources.com] *On Behalf Of *Bruce King
> *Sent:* Saturday, March 03, 2012 19:10
> *To:* Global Straw Building Network
> *Subject:* Re: [GSBN] Plaster thoughts****
>
> ** **
>
> ** **
>
> Marks, funny you should ask!****
>
> ** **
>
> Tim Owen-Kennedy and I have been roped into working in Kibera (Nairobi)
> Kenya on the Human Needs Project (http://www.humanneedsproject.org/), one
> part of which involves renovating earthen huts in the shantytown that is
> Kibera.  The renovations mostly involve applying a nicer and more durable
> finish to the badly eroded wattle-and-daub walls.  You can see pics on the
> website;  their main thing is to build a community center that provides
> clean toilets, potable water, and solar-powered charging stations for
> mobile phones.****
>
> ** **
>
> For the earthen walls, our client came to us already wedded to a
> cementitious system based on PVA fibers that bond to cement and give
> concrete/stucco huge flexibility and crack resistance.  Tim's and my job,
> which we're in the middle of right now, is to devise and test PVA-cement
> mixes that can bond to the earth & stay put.  We are going to test for
> delamination in a weather chamber that wildly fluctuates temperature and
> humidity.  We are acutely aware of the innumerable previous problems all
> over the world  associated with cement-over-earth, and know we need to have
> as much vapor permeability as possible,  So far we imagine using only
> large, course sand (no fines), minimal cement, the PVA fibers (they look
> like bleached, finely chopped straw), and possibly some lime.  As usual, we
> have very little time or money to play around.****
>
> ** **
>
> Well report back to everyone as we progress over the next few months.****
>
> ** **
>
> Bruce King****
>
> bruce at ecobuildnetwork.org****
>
> (415) 987-7271****
>
> ** **
>
> ** **
>
> ** **
>
> On Mar 3, 2012, at 8:20 AM, huffnpuff at q.com wrote:****
>
>
>
> ****
>
> Mark and All,****
>
>  ****
>
> I am sure you will be aware of some of what I suggest, as it's common
> knowledge in the earth plaster world. Too much clay, too little
> sand/aggregate, the size of the sand/aggregate (too fine sand) can all
> cause excessive cracking. Removing clay, adding more sand/aggregate or
> upping the size of the sand/aggregate could help. I've found that the
> more/longer straw added can eliminate higher clay content cracking. I've
> used a 1:1:1 ratio of clay, long straw, masons sand for a very sticky,
> super strong, low/no cracking application to stick as a base over foam,
> lumber and plywood (placing some of this mix on the surface, tack mesh to
> subsurface, place more mix, for an added mechanical bond).****
>
>  ****
>
> When you start adding lime and cement to a mix sounds like what we do in
> the US. If it doesn't move, get a bigger hammer. It's not better living
> through 'bigger hammer' chemistry. Often less is more. I think you'll
> find some of your answers to cement earth plaster ratios in a study by the
> U. of Penn as they attempted to do some repairs to the mortar on ancient
> ruins in the Mesa Verde and Chaco Canyon adobe structures.http
> ://repository.upenn.edu/cgi/viewcontent.cgi?article=1044&context=hp_theses
>  You'll find test results on "tensile strength, modulus of rupture, water
> vapor permeability, and water porosity (respectively) (and freeze/thaw) *
> vs*. volume-percent of Portland cement for amended mortars" . ****
>
>  ****
>
> Also, you might check out Stabilized Compressed Earth Block sites (adobe
> block on steroids...it's what happens when engineer types make adobe
> block). My limited experience with SCEB's is they only use about 6-12%
> cement...lime may be substituted, but don't quote me. Check out the
> Auroville Earth Institute  www.earth-auroville.com for mixes using
> cement. Maybe others can chime in here with knowledge on substituting lime
> for cement. Of coarse, different areas have different clays that react in
> varying ways so experimenting with different mixes/ratios would be
> prudent.  The one advantage of using cement amended earth mixes is that it
> hardens much faster so the results of your experimenting is swifter.****
>
>  ****
>
> For a shameless plug for the Conference in Sept. 2012 http://www.
> strawbaleconference.com/index.html the Auroville Institute will be
> represented at the conference by a presentation by Richard Presley. ****
>
>  ****
>
> If the locals insist on using cement additives to the earthen plaster mix,
> visiting the information on these two sites should help with your educated
> guess as to ratio's. I did some extensive stone work this last summer and
> wanted to use an earthen mortar. I used a 9:1 mix of my earth plaster
> mix/cement. My mason buddy thought I was nuts. Eight months later, 4 feet
> of snow and lots of freeze/thaw in our Colorado winter climate and that mix
> seems to be holding up amazingly. There's little to no degradation of the
> mortar.****
>
>  ****
>
> For those interested in pre-fab straw bale walls and those using cement
> stucco's these amended earthen mixes may be worth noting. ****
>
>  ****
>
> Hope this helps Mark...Regards,****
>
> Mark (see you in September) Schueneman
> Colorado Straw Bale Association****
>
> 303-444-6027 hm.
> 303-591-9841 cell****
>
>  ****
>
>  ****
>
> ** **
> ------------------------------
>
> *From: *"Mark Jensen" <markj at redfeather.org>
> *To: *GSBN at sustainablesources.com
> *Sent: *Saturday, March 3, 2012 3:44:05 AM
> *Subject: *[GSBN] Plaster thoughts
>
> Hello et al,****
>
> ** **
>
> I am in Kenya right now working on two straw bale buildings, stacking for
> both Monday and Tuesday. I am struggling with plaster thoughts. I guess the
> last plaster they did was clay, sand, cow dung, chopped straw, lime, cement
> and water. Nobody knows the proportions but they had severe cracking, like
> a dried up lake bed.****
>
> ** **
>
> Now they want to do 1 1/2 bags of lime, 1/2 bag cement, 4 wheelbarrows of
> sand, chopped straw and water. This seems like a recipe for disaster to me.
> They are on a very short budget. I suggested harvesting clay and just doing
> a earthen plaster, it's free other than some labor to harvest. ****
>
> ** **
>
> Any thoughts on the recipe above?****
>
> ** **
>
> Your input would be appreciated.****
>
> ** **
>
> Asante Sana, Thank you very much,****
>
> ** **
>
> Mark****
>
>
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>
> ****
> ********
>
>
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-- 
Tim Owen-Kennedy, Owner
Vital Systems, natural building & design
P O Box 751, Ukiah, CA 95482
www.vitalsystems.net
888.859.6336
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