Cost-Benefit Analysis of Cobwood -- 25 August 2010 -- I worked all day Saturday and Sunday raising this wall. On Sunday I had to quit around 5pm, not because I was out of energy or materials, but because I knew that if I did any more, I would have nightmares about it. Monday I couldn't bear to work on the wall so I did a bunch of chainsawing and drawknifing.
Natural building is not fun. It has many advantages over unnatural building: it's cheaper, the structures are more beautiful, and it is more meaningful to shape something out of materials you have cut and dug with your own hands, than out of industrial products from Home Depot. This makes it much easier to feel motivated for natural building. But the actual work, just like unnatural building, is a tedious chore.
Ianto Evans has written that he loves cobbing so much that he feels sad to finish a house. It's because freaks like him write books that the rest of us get discouraged. Someone who loves doing something -- building, writing, whatever -- will not hesitate to do twice as much work to get a ten percent better product, while gushing about how much fun it is. Then we ordinary people get bogged down in the work and think there's something wrong with us. It should be the other way around: if people who hated building wrote books about building, they would not even do eleven percent more work for a ten percent better product. They would find all the shortcuts and good-enoughs, and then, if you loved building, you could go far beyond that. Joel comments:
I think the ideal how-to book might be written in collaboration, with someone who loves the field and has explored it thoroughly supplying options that others might not see, and someone who hates the experience providing the constraints you describe.
Anyway, the walls in the photo represent about 25 human-hours of work -- but that was starting with a stack of split wood and a pit of pre-mixed sand and clay. By the way, pre-mixing sand and clay more than a week in advance is a mistake. The water tends to rise to the top and evaporate, and the sand tends to sink to the bottom, and then it all needs to be reprocessed, which takes just as much work as mixing the sand and clay in the first place. I should have spent that time cutting wood.
So far I have used about as much sand and clay as I expected, less straw, and much more wood. I think I figured this out last year by doing math on the volumes of the two fallen hemlock trees, and then I forgot it because it was too unpleasant. Yes, the wood in
these trees is not enough for this little structure. And I can't kill more trees because the wood needs to spend two summers drying. I'll be able to find enough undecayed old fallen wood to finish the wall, but now I'm thinking...
Cobwood has a big advantage over cob if you already have a pile of cordwood. You just stick the wood in the wall and you only have to make half as much cob. But if you have to pick out trees, cut them down, take off the limbs and bark, saw them into rounds, and split them, that's actually more work per volume of wall than digging up and mixing sand and clay. Also, integrating wood and cob takes more work than just piling up cob. Also, it's easy to taper a cob wall, so it gets thinner near the top, but logistically difficult to do this with wood. Also, cordwood doesn't like tight curves, because the ends are spaced too closely on the inside and too far apart on the outside. Also, although everyone says that cobwood can hold up a roof, in practice everyone uses it to fill in between posts and beams. This little structure will be the first example I've seen of a roof-bearing cobwood wall.
My conclusion is that cobwood is only worth doing in a special case, where you already have a big pile of wood, and you're filling in straight or slightly curved walls. Otherwise, go with all cob.
Woodhenge -- 18 August 2010 -- "In ancient times, hundreds of years before the dawn of history, lived a strange race of people... the Druids." Seriously, in the photo you can see Chuck and Agamemnon, who came up to help with this year's project and clumsily stalk chipmunks, respectively. The wooden thing is a door frame, with the curved part made out of a western redcedar, and the straight part made out of a grand fir. The fir was already dead and I killed the cedar for exactly this purpose. It was growing upside down from how you see it.
Chuck has some construction engineering skill, and we decided to join the two pieces of wood with a
mortise and
tenon joint. Those links go to photos that were taken when both were still in crude form. I forgot to bring a chisel, so we roughed out the perimeter of the mortise with a drill, and then got the center out and smoothed the edges with a mini hatchet, a mallet, the sharp part of a hammer, and a whittling knife. It helped that the center of the log was rotted out. The tenon just took some sawing. I made the mistake of cutting the tenon a little big, figuring that we could always make it smaller. But then it took me a long time to get it small enough to fit.
Then we had to fit the parts together so that the legs were parallel, cut some wood off the bottoms of the legs so the whole thing stood up straight at the right height, and cut away some wood so that we'd have a smooth joint, which you can see in the photo. The "O" was to remind us which side of the log faced the outside of the structure. Chuck was a good sport about holding the thing up while I checked it with a level and figured out how much wood to cut. I made some lucky guesses and we still had to stand it up and set it down a few times.
Then we had to figure out how to hold it in place for the next month or two until the walls are filled in around it. I was going to use long pieces of wood nailed to the frame and braced against the ground, but Chuck had the clever idea to use a tripod of wires and stakes. In the photo up top he's wrapping the remains of an orange t-shirt around a wire so people don't run into it. And the bottoms of the frame are held in place with cob...
Cobbing Begins -- 18 August 2010 -- Here you see the beginnings of a cordwood cob wall, a.k.a. cobwood. Chuck and I are beginners, and we probably did this in about five hours over two days. We're digging pre-mixed sand and clay out of the pit, and some of it is half dried and needs to be mixed with wetter stuff, so we're doing that while we also mix in the straw, using the popular method of stomping on a tarp and then lifting the edge of the tarp to fold the cob over on itself. Then it's just a matter of picking out the right pieces of wood and packing the cob around them. I'm already learning tricks, like to wet the cob under a new piece of wood, so it fits down more snugly, and then to stuff more cob in around the edges, and lay sheets of cob on top to prepare for the next piece of wood. The door frame is wired to pieces of wood on both sides. Those little holes everywhere on top of the cob are so the next layer fits more securely.
When we imagine new "technology", we're usually thinking about space robots and happy pills, not dirt houses. But Becky Bee invented the tarp mixing method in the 1990's, and Ianto Evans made important improvements to ancient cob technology only a few years earlier. I like to think we're at the beginning of a renaissance, a conjunction between modern consciousness and ecological values. More now than at any time in human history, the people not mired in tradition, and the people trying to live in balance with other life, are the same.
Got Straw -- 11 August 2010 -- Wheat harvest has been going on for a few weeks now, and finally someone offered fresh straw on craigslist, and cheap, only $1.25 a bale! It was in Kettle Falls, an 80 mile drive north of here, but it was a nice day for a drive and I had never been up there. Along the way I picked up two hitchhikers, a young hippie from Connecticut, and a woman from Belarus, who were on their way to a Rainbow gathering. I dropped them off and found the farmer, who led me to the field in the photo. The bales were just barely small enough that I could cram four of them in the truck and still get the cover on in case it rained. Then I took a nice shortcut to drop them off at the land, driving up Flowery Trail Road from Chewelah to Usk.
A second shortcut, taking the "back road" through the hills on the other side of my land, didn't work out so well. It looked simple on the internet, but in practice there were unmarked forks and roads that got worse and worse. Finally I gave up and took the long way around. Later when I got back, I zoomed in really close on Google maps and discovered that the satellite photo does not show a road where the overlay shows a road! There might not even be a way through, but some time I'll explore all the roads back there on my bike.
Anyway, now I have four really nice bales under a tarp on pallets, and at least one visitor coming this weekend to help build cob.
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Cost-Benefit Analysis of Cobwood -- 25 August 2010 -- I worked all day Saturday and Sunday raising this wall. On Sunday I had to quit around 5pm, not because I was out of energy or materials, but because I knew that if I did any more, I would have nightmares about it. Monday I couldn't bear to work on the wall so I did a bunch of chainsawing and drawknifing.
Woodhenge -- 18 August 2010 -- "In ancient times, hundreds of years before the dawn of history, lived a strange race of people... the Druids." Seriously, in the photo you can see Chuck and Agamemnon, who came up to help with this year's project and clumsily stalk chipmunks, respectively. The wooden thing is a door frame, with the curved part made out of a western redcedar, and the straight part made out of a grand fir. The fir was already dead and I killed the cedar for exactly this purpose. It was growing upside down from how you see it.
Cobbing Begins -- 18 August 2010 -- Here you see the beginnings of a cordwood cob wall, a.k.a. cobwood. Chuck and I are beginners, and we probably did this in about five hours over two days. We're digging pre-mixed sand and clay out of the pit, and some of it is half dried and needs to be mixed with wetter stuff, so we're doing that while we also mix in the straw, using the popular method of stomping on a tarp and then lifting the edge of the tarp to fold the cob over on itself. Then it's just a matter of picking out the right pieces of wood and packing the cob around them. I'm already learning tricks, like to wet the cob under a new piece of wood, so it fits down more snugly, and then to stuff more cob in around the edges, and lay sheets of cob on top to prepare for the next piece of wood. The door frame is wired to pieces of wood on both sides. Those little holes everywhere on top of the cob are so the next layer fits more securely.
Got Straw -- 11 August 2010 -- Wheat harvest has been going on for a few weeks now, and finally someone offered fresh straw on craigslist, and cheap, only $1.25 a bale! It was in Kettle Falls, an 80 mile drive north of here, but it was a nice day for a drive and I had never been up there. Along the way I picked up two hitchhikers, a young hippie from Connecticut, and a woman from Belarus, who were on their way to a Rainbow gathering. I dropped them off and found the farmer, who led me to the field in the photo. The bales were just barely small enough that I could cram four of them in the truck and still get the cover on in case it rained. Then I took a nice shortcut to drop them off at the land, driving up Flowery Trail Road from Chewelah to Usk.