Humans are creative creatures, and no other building medium is as creatively fluid as cob. We’ve experienced dozens of cob houses on this trip, and each one is as individual as the person (or team) who built it. Yes yes, I know, ‘form follows function’ and every design feature has to be justified by its practical application, but form also follows fun, and if you are going to have built-in shelves, why not make them arched and finished with beautiful mosaics? Oh, and there is a little space left above the arches, so how about another set? :)
The walls are going up fast, and it’s time to think about the ‘eyes and mouth’ of the house, windows and doors that is. Hey, that’s less cob walls we have to build ;)
D O O R S
The approximate area of the house we are constructing is 550 sq feet. We have 20 days and 15 not-so-experienced people to get the walls up and to put a roof on it (well, at least set up the ridge beam). Will we make it?
First few days are spent on getting familiar with the cob mixing process. In theory, it’s pretty simple.
- We place the dry materials (soil, clay and sand) on a 8 x 10 ft tarp and roll it by pulling on the corners
- Then we add water to the mixture and roll it again
- We stomp the mixture with our feet until it’s evenly moist and mushy. “Mud dancing”, we call it.
- Final step is to add straw, roll it again and dance on it until all straw is integrated
In practice it turns out to be pretty simple as well. If the mix comes out too wet, add a bit more soil and straw. If it’s crumbly, add clay. The material is very forgiving, and there really isn’t “the right” way to mix it. As long as all the materials are integrated into a malleable mix, it’s ready to be applied.
This is our process.
The house we are building will be a home to a family of four: Mom, Dad and two young boys. The task at hand is to build a solid cob wall around an existing yurt structure and to build an additional room on the side to serve as the parent’s bedroom.
When building with cob, it is best to build along the whole perimeter of the building at once. When cob walls dry, they become a monolith, like one giant house-shaped rock, really! I’ve read about this in “The Hand Sculpted House” book, but I didn’t really comprehend this until I mixed my first batch of cob and made a test brick. Once it dried, neither smashing it nor throwing it affected its brick-ness. No words to describe this phenomenon, only a personal experience of dried cob.
But let’s start at the beginning, and any self-respecting house begins with a solid foundation.