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cover with chicken wire or not?  RSS feed

 
Rick Kruszewski
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I'm building a structure using poly bags and would like to omit covering everything with chicken wire or lathe. How well will a lime/cement/sand plaster adhere to the poly bags?
 
Jay C. White Cloud
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It won't and one of the many shortcomings of many EB builds today...

I still prefer hemp or jute cloth bags for an EB building and more traditional applications of the techniques. I, et al, have warned against these plastic bags for some time, yet there is an every insurging trend to use them. I haven't even been able to find the cloth bags for a while now, as they were once the most common. I think that the entire EB movement would benefit greatly from moving away from these plastic based bags and back toward cloth. I also do not recommend EB as a foundation material as any structural/chemical/biological/UV degradation of the bag will result in a structural compromise of one of the most important aspects of a build...the foundation.

Unfortunately, I see a great many builds that are wonderfully executed, with great attention to detail and almost completely natural materials. Many of these builds could last hundreds if not thousands of years if not for the sake of placing them on a foundation that is being held together by a very transient materials and its a format that can not easily be repaired or modified when the need will arise like stone, timber, or related vernacular methods....

I think EB is great...when

Done in context...

Is well understood...

Is only structural to itself...

Is a natural woven material not plastic...

Is used more for a "form" that holds a self solidifying and hardening natural matrix...(i.e. cobb, straw clay slip, limecrete insulative mixes, etc)

That's my2ยข...

 
martin cubak
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I tried first to do cob plaster on my bags ,but it wasn't what I expected so did lime,sand,cement plaster.....its great ! and it was fast too. You need chicken wire or something !!! it will not hold. I did not install my ties for chicken wire when I was building .It is time consuming to fasten chicken wire to bags without ties.I did it with 14ga galv.wire that I bend to (U) shape and hammer it gently in the grooves.
 
Lauren Magnolia
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...excuse me for barging in on a earthbag-focused topic <3 but I have a similar question which I will now copy/paste...

Hey there, Permies Universe!!
My husband and I are in the midst of a relatively unprecedented home-build, at least for our area.
What started as a cob-house has become a timber/cob hybrid, subject to both buidling code and material availability. Our current inquiry is in regards to the exterior siding...
We plan to lime plaster/paint the exterior, which currently consists of OSB on balloon frame. Plan A is to wrap with tar paper, then chicken wire/lath, then lime plaster with a coat of lime paint to finish.

Now for the Q&A...
A) Would a coat of lime paint on the OSB be enough for the plaster to adhere or is the tar felt & chicken wire lath the best option? How about lime paint, lath, and then plaster?

B) What sort of options are available to us besides chicken wire, which is currently the best bang for our buck.
Has anyone any experience with "wood lath"? I hear it's often found and recycled, but from where?

All input is greatly appreciated!!
 
Bryant RedHawk
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
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Lauren, I have posted an answer to your questions here Lime plaster over wood

Wood lathe is also known as batten board it is simply thin 3/8" thick x 1 1/2" wide wood. Now a days we cut it from 2 x 4's or any 2 by lumber on a table saw.
Usually it is only used for restoration work since the new metal lathe material gets a better grip on the plaster and application not only is faster but also smoother.
 
Bryant RedHawk
gardener
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
243
chicken dog forest garden hugelkultur hunting toxin-ectomy
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Rick, you don't have to use chicken wire or metal lathe on the polypropylene bags. I would probably use the metal lathe myself but I have seen it not used with an earthen plaster.
Earthen plaster works best without the wire/ lathe I'd use it for the base coat(s) and then use a lime top coat to seal the earthen plaster from moisture and for easier cleaning.

To get a good bond to poly bags, first fill in the depressions with the earthen plaster mix and let that dry.
Then come back for the first coat, use two coats of the earthen plaster and let dry between layers before putting on the lime top coat.
 
Eivind Bjoerkavaag
the navigator
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Jay C. White Cloud: You make it seem you have some personal vendetta against earthbag, I don't have any comments on the use of cloth but rather I'd like to comment on how you seem to believe it is the bags that are doing the structural work. You say you like earthbag when it "Is only structural to itself..." and "Is used more for a "form" that holds a self solidifying and hardening natural matrix...(i.e. cobb, straw clay slip, limecrete insulative mixes, etc)"

Earthbag construction is proven to withstand huge loads.

If the material inside the earth bags is a proper mix of clay, sand and cement the earthbag structure could take immense loads.

However, if you are thinking of people with no understanding of the building technique and you suspect they will only use silt - no clay - no sand - no cement, then I understand how you seem to think the plastic bags are structural.

 
Jennifer Meyer
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Location: North Carolina
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Bryant RedHawk wrote:Rick, you don't have to use chicken wire or metal lathe on the polypropylene bags. I would probably use the metal lathe myself but I have seen it not used with an earthen plaster.
Earthen plaster works best without the wire/ lathe I'd use it for the base coat(s) and then use a lime top coat to seal the earthen plaster from moisture and for easier cleaning.

To get a good bond to poly bags, first fill in the depressions with the earthen plaster mix and let that dry.
Then come back for the first coat, use two coats of the earthen plaster and let dry between layers before putting on the lime top coat.


To add to Bryant's comment, I'm in the middle of an earthbag project using Cobb over poly bags. The application method Bryant describes works perfectly. So far, I've cobbed the inside and outside of a hen house and the outside of a storage shed.

Fill in large gaps first, wait a day or two for it to dry, then expand the cobbed section with more cob. The interior ceilings are challenging, though. The cob likes to drop to the floor.
 
Jennifer Meyer
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Location: North Carolina
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I've found that if you keep your layers of cob thin and use a mixture with a lot of straw to keep the cob lightweight, the cob sticks to internal ceilings very well.
 
Christopher Steen
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This thread keeps bumping up top so here is my take.
Treat EB plaster prep & lathing like other wall systems, framed or bale etc. These industry standards and code requirement, while stucco industry based, have developed over time and testing. They are a fair starting point to work from.
Just because i can trowel or spray a cement, lime, gypsum or clay based plaster on walls or even a flat overhanging ceiling and get it to stick doesn't mean that it is correct or good enough. And I can get a standard masonry mix (lime cement sand) to stick and be scratched/ sponged just fine to a poly dome ceiling without netting, but I don't. If you Remember Mechanical and chemical bonding compatibility; Sratch and sponge correctly; aggregate distribution and fiber--then you will have a durable awesome plaster. But unless I'm skimming drywall, I typically use some type of mesh. it's cheap and quick. Just shoot on stucco or chicken netting for the scratch coat with a wide crown stapler like the pros. Quick, secure, strong. No more than an inch leg if you've cement stabilized or have gravel in the bags. You went through the work to build a superior wall or dome system durable enough to last a long time. Bestow your plaster with the same honor.
Lath around all stops: Windows, doors, eaves, sills, stems , parapet, termite/water flashing, exterior boxes/lights, etc. Flash your openings, even if it means some hippy method of mixing linseed in your bucket of earthen around Windows, or waterglassing the lime around the Windows.
With earthen plaster over jute, burlap or raschel mesh, plaster netting is more optional. But put this way, stuff just sticks to bales, and I'd still chose to mesh my bale walls like the codes require. If going though the effort, and you gottA skimp for the sake of wanting to skimp, skimp somewhere else. Plaster is an awesome and beautiful thing, so let yours be for a long time.
Also, I enjoy Jay 's posts, even his EB posts, but at 7 cents per misprinted gusseted UV stabilized poly bag and 80 cents per jute bag, I'd be hard pressed to take the jute bag even with the prices switched.

Let us always remember what Jay wrote,
"I think EB is great...when
Done in context...
Is well understood... "
(Quote shortened out of context for my purposes)
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