Okay, I have been wanting to build a cob house for a while now, and my land is perfect since there is a crazy amount of clay in the soil...but that is also the problem because any water I get stays...so I've been told cob is completely infeasible. But...I was researching ancient pottery techniques and found that the natives made their pots and bowls out of basically cob, then baked them to make water tight vessels. So, my question is...theoretically speaking, could you fire the walls of a cob house to add to the water resistance and durability of the cob?
Interesting theory- I have a similar situation and have basically been playing with the idea of soil cement. I have seen some artist do some interesting outdoor projects of sculpting with cement (which is derived from the earth). The thing about kilning dirt, I heard a while ago, is you have to be careful what type. I guess certain type holds water inside, and then, when it heats, it explodes. So, that isn't what you want. Of course, that's kilning bricks, which I am not at the luxury of looking up at the moment. So, what might work better is a wooden exterior that is nice and water-tight and a cob interior, where things would be dry (except during floods and roof leaks).
Just my 2 cents.
Location: Ozarks zone 7 alluvial,black,deep clay/loam with few rocks, wonderful creek bottom!
posted 3 years ago
Maybe this guy has some information you could use......he's making a roof though, not walls, and firing the tiles. I couldn't find the video on just making the tiles though...I know I watched one a few weeks ago.
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TO: Jessica O'Leary
FROM: Eric Koperek = email@example.com SUBJECT: Sintering Cob Homes
DATE: PM 7:08 Wednesday 3 July 2016
(1) It is possible to "fire" clay walls to produce a low-temperature ceramic. However, the energy cost is enormous = GIGANTICALLY HUGE. The Iranians did work in this area before the Revolution, and they had billions of gallons of cheap oil at below $1.00 per barrel. They also had the advantage of a bone-dry desert climate to dry walls before firing. It takes many, many months to dry walls or they will explode when heated.
(3) Adobe and cob houses can be built in damp climates. There are great numbers of these structures in Europe; some date back to Colonial times.
(4) There are 6 rules for building mud houses in damp climates. Follow these rules religiously or bad things will happen.
(5) RULE: Build a wide porch around entire structure to keep rain and snow off walls.
(6) RULE: You must have a waterproof layer between the foundation and walls so moisture does not wick up from the soil into your walls. Glazed ceramic tile, copper sheathing, or a thick layer of tar is essential.
(7) RULE: Use only natural lime plaster to cover walls. Do not use any kind of waterproof coatings or paints on walls (inside or out). Walls must be able to breathe = release moisture. No oil paints, no acrylics, no rubbers or plastics, no glues. Use nothing but lime plaster, lime wash, and lime based paints with earth pigments.
( RULE: Foundation requires DEEP trenches below frost line = 3 to 5 feet deep depending on your climate. When in doubt, dig deeper. Trench should be at least 12 inches = 1 foot wider than building walls. Fill trenches with COBBLESTONES = round, river rocks. Do NOT use crushed stone. Round stones will not pack tightly so there will be many large air spaces for water to drain freely. Crushed stone packs tightly so there is little air space. IT IS ESSENTIAL TO HAVE MAXIMUM POSSIBLE AIR SPACE UNDER FOUNDATION TO PREVENT FROST HEAVING. A dry foundation is your first defense for an earth walled house. Drain foundation trenches downhill = to a lower elevation. You want to lead water away from the foundation.
(9) RULE: Build oversize gutters and downspouts and make sure these drain down slope = away from building. Alternatively, build surface gutters, or rain trenches to lead water away from walls.
(10) RULE: If there are any slopes ABOVE the house, build diversion trenches and swales to intercept surface and ground water before it reaches foundation. First diversion trench should be 50 feet up slope from building to be protected. For best results, build house on a small knoll or hill so all slopes drain away from foundation.
(11) Clay tile roofs are common throughout Europe. This technology dates back to Roman times. Flat tiles are most commonly seen in Northern and Central Europe. Curved "Pan Tiles" are most often seen in Spain, Portugal, and Italy.
(12) Please note that firing clay, especially at low temperatures, does NOT make the ceramic waterproof. Ceramics must be glazed = coated with glass in order to be completely waterproof. The closest thing to "waterproof" ceramic is porcelain tile which is very dense and requires special clay (kaolin) and extremely high heat in order to manufacture = you can not do this with common adobe or cob walls.
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