I'm new here so I hope this subject hasn't been extensively covered already.
I am contemplating an experiment with what I am calling laminar cob.
The idea is to build a woven branch lattice which I would cover with burlap. Next, make the cob mixture, a little thin and without the straw. What I'd like to do is "paint" the strawless cob mixture onto the burlap in a thin layer and press another layer of burlap into it. Repeat this process until I get a membrane of desired thickness and finish the surface with a slightly thicker layer of cob slurry.
This idea arises from an interest in constructing relatively thin membranes for interior walls and perhaps roofing.
On a related topic, does anyone know anything about cob roofs, specifically, how to weatherproof such a roof?
Does anyone know anything about such a process? Have you tried it or seen anyone try it? Can anyone think of a reason it might not work?
Coating burlap with portland slurry is pretty common as a way to use it as lath or formwork for ferrocrete. Extremely thin sculptural layers would be the advantage of such a system, but resilience would be the question as it relates to cob. Each cob formulation is different base on clay profile and binder type. Look up wattle and daub on u-tube and find lots of ways to coat a screen or lattice or panel with mud will pop up. My personal favorite is to use light straw claw, woven thatching style into the lattice, completed with clay or cob finish.
cob as roof works in low-rainfall, extreme desert climates. cob as an insulator under a more traditional or ferro-crete/gunnite roof would work as well. the better option is to use packed light straw clay. it is substantially lighter and easier to incorporate into a standard structure. on the current cottage i am building, i am going to embed large timbers at second floor level, purlin with medium timbers, lay used galvie tin over the boards, and make a second story cob/earthen floor. needless say the structure to do this safely is very very heavy, and the size is small. a simple, small cob roof could be made the same way, just float or embed framing into the cob, add tin, shakes, or rubber.
Location: Knoxville TN
posted 7 years ago
This is great. I've been thinking about Portland cement a lot too. I'm a way away from building anything but I'm planning to build some "models" to get a sense of what is possible.
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