Ours were reclaimed from a building destruction project.
You can also use other building materials such as squarish rocks or homemade bricks.
The soil is clay about 12-18" down in our garden space, and we harvested our own by digging down to it.
-Large Mixing Container
We used a plastic sand box/wading pool from a toy store that came with a cover to keep the cob protected between uses.
-Large Sewing Needles
A senior staff member, a 65-year-old Pakistani woman, enjoyed supervising this project because she had seen so many houses built like this in her country. This project took about five months of work with the entire school participating. It was not easy and we made myriad mistakes, but I still highly recommend the process! Somewhat unfortunately, the house is now largely deconstructed, with only the foundation remaining... I am curious to see what this project will become next!
Harvest clay. Our best source was in a dark corner of the garden opposite our construction project. This hole ended up being about four feet deep and three feet in diameter, going around a horizontal, rusty pipe deep down, and finally hitting the water table!
Mix clay with a small amount of water, as you can always add more later but it is difficult to deal with too much. Add in some broken-up, tiny pieces of hay, and a bit of sand. Mix with feet!
Clean feet off! Hand and foot prints are fun to make before getting hosed off.
Create the foundation by putting down a thick layer of cob and laying out the first bricks, soaked in water and then surrounded with cob.
Here are our biggest mess-ups with this phase: Our pieces of hay were too big; they should have been more finely shredded. Our base was placed atop sand; it should have had a more solid, thicker, and level foundation. See the cob on top of the bricks on the lower right hand corner of the photo? These were too low and a window (read: less structure) was put above them. After several rains and for some reason some work men coming and removing the roof (which had been a structural element) and placing a large branch across the top before replacing the now unattached roof, became the downfall of the structure.
Teachers and children work together.
Add layers and layers and layers.
Note further issues:
The house needs to be kept somewhat moist as it is constructed, for which I used the mist nozzle on a hose. The area that was too low on the foundation now has an outward sloping wall. We added some chicken wire to help strengthen these walls, and added an exterior buttress to the left hand side. Note also that there are spaces between some of the bricks... These should have been filled as we went to further strengthen the building. Sometimes we got tired...
Make plaster to coat the finished house. This is the same process as making cob, but with a finer clay (kaolin), mixed with even tinier pieces of hay, a bit of mica for some shine, and pigment.
We chose a blue finish for the outside and orange for the inside. This is further confirmation of the blue light of the sun; the blue pigment just disappeared again and again in front of our eyes, the more we added. Largely, a waste of time, money, and effort!
We constructed a frame of bamboo harvested from right next to the house and tied the pieces together with twine, then attached it with more cob and plaster.
The canvas was a drop-cloth we coated with Scotch Guard then tied to the frame with twine.
Even though we applied the fabric treatment, the roof still became moldy and did leak a bit in the rain. We also covered it with pieces from a large bush we took out, and that looked pretty cool for a while.
The plaster feels cool and soft.
Lesson plan by Heather Taylor, firstname.lastname@example.org. You are welcome to share all materials with credit to her.