Could this be it? A way to make houses as beautifully sculptural as only cob houses can be... but to also make them effectively insulative? Some have tried to incorporate straw bales into cob walls, especially on the North side of the house in the Northern hemisphere. But because straw bales are cuboid in shape, although they make for excellent rectilinear building blocks, they can't curve well. If you try to bend them into shape, you're left with lots of gaps that must be filled with loose straw, which doesn't have nearly as high an R-value.|
Cob-bale sandwich walls have tended to consist of a medium-thick cob internal wall for thermal mass, and a thin cob external wall for some structural support and plaster cover. This model is an intelligent one, let's work with it. Now, instead of first placing the bales, then cobbing onto them, letting the bales determine the shape of the wall... what if we first sculpted the walls with cob, internal and external, leaving a gap between the two walls of about 12 inches... and then stuffed the insulative layer inside after the fact?
Straw-clay slip -- loose straw dipped in clay -- is one option, though an inferior one. It is usually used in 2 x 4 inch thin wooden stud walls where straw bales won't fit, and although it provides a modicum of insulation, it's not nearly enough for our purposes, though certainly possible in milder climates. But what about papercrete, hybrid adobe, or paper adobe? Their insulation values are far higher, and they also lend themselves to a cob sandwich building technique. In this case, the cob walls replace the wooden forms usually required, conserving even more resources.|
This use of paper building techniques is even easier for an owner-builder. Instead of having to create vast amounts of the paper blocks all at once using large industrial equipment, one could manufacture a relatively small amount of the mixture at any one time, and use it only to fill the gap created by that very day's worth of cob building. It also means that instead of having to do the same tasks repeatedly ad infinitum, you could vary your workload, giving your muscles an all-around workout and your brain a bit of a break.
Now, it's true that the paper blocks that a long time to dry. Well, cob walls also take at least a whole season to dry fully. Cob walls themselves will allow moisture to pass through, so the paper mix on the inside can evaporate, albeit very slowly. The fact that the paper won't dry too quickly means that when the next layer is added on top of the first, the two layers can physically bond and integrate, creating a solid, incredibly strong monolithic internal insulating wall. And of course, they'll always be able to evaporate upwards, where they won't be shuttered in.|
If there's a real concern that the internal paper mixture won't sure quick enough, and that it'll never have a chance to fully solidify, a small amount of cement can be added to stabilize the earth. In that way, it'll mostly dry within a single day, quicker than the cob, yet still be slightly viscous enough to bond with the next layer of cobcrete a day or two layer, making sure the wall is internally consistent. As soon as I mention the word cement, I know the cob purists are bound to freak out; but hear me out here:
First of all, this is not pure concrete, it's papercrete (or hybrid adobe), which is still somewhat breatheable, it does allow moisture to pass thorugh. And I know we have a knee-jerk negative reaction to cement being used to plaster the outside of an earthen wall, as we should. But this small amount of cement won't be on the outside, it'll be on the inside of the wall; so both cob walls will still have ample opportunity to shed whatever water they take on and remain structurally stable.|
Unless I've missed something here, I think this still-conceptual wall system may be the easiest way to build an almost-all eco-earthen house for extreme climates, that's round, warm, and fuzzy, and still doesn't require any high-tech industrial equipment before, during, or after. The Peak Oil Papercob Wall... can you find fault with it? If so, then let me know before I break ground, so I can incorporate your ideas, because I'm itchin' to put it into practice and see what comes of it. With love of earth =)