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.
5 replies on “Building Foundation and Stairs – “Cob Cottage Company” Natural Building Apprenticeship at Spirit Pine Sanctuary”
We need cob homes for humanity. Use social networking to make connections and get building/training where we can.
You don’t need to put anything between the stem wall and the cob, except for clay slip (water and clay mix about the consistency of thin sour cream). Slip helps cob to stick to the rock surface.
There are some more photos and details of applying cob to foundation at a later post: https://www.permacultured.us/2013/05/cob-mixing-basics-in-natural-building/
Thanks, Tatyana! I’m thinking about lime mortar actually, all these books i’ve read on cob building made me not liking cement 🙂 but since it’s not very easy to find it here – i’m from Ukraine – there is a chance i will use a cement after all.
Do you recommend to put something in between the stem wall and cob? Something to stop moisture come up into cob?
Yeah, dry-stacking the stones in a way that locks them in (keyed in) works well (from our experience). The stones have to be place so that when you walk on top of the wall, none of the stones move or wiggle. Then cob walls on top of the stones will press them in even further. Start with largest stones and place smaller ones in-between to lock them in, like puzzle pieces. Best of success to you!
If you are not fully confident with dry-stacking, you can use cement mortar to secure the stones further.
hello! i’m going to build a cob house myself this summer and i was very much worried about how to make a foundation and stem wall – we don’t want to use urbanite, and the stone we can get is not that of the right geometric form, so i thought i won’t be able to stack them right ans something will go wrong. but as i can see you are not troubled with that and it goes just fine, is it?
thank you for this post, it gave me the thought that it will be fine with the stone we are going to get! 🙂