Adobe, or cob, is basically a sun-dried mud. It has been used throughout the world, in many different time periods. Several buildings, hundreds of years old, still stand.

The downside is that it takes a lot more time to build with adobe than it does with many other building materials. It also requires some energy – you’ll be moving a lot of mud.

1)      Put some earth (take out rocks) in a jar, add water, and shake real well. The sand should settle to the bottom, then silt, then clay.

2)      Make some test bricks out of each sample. Too much sand will result in a crumbly, weak brick. Too much clay will shrink and crack as it dries.

T Bricks
The traditional way to make bricks is to set your forms on the ground, pour wet mud into them, and remove forms. When the bricks have dried out and cured, you then lay them as you would any other brick, using adobe as mortar.

We do it a little differently. We set our forms up on the wall itself and poured the bricks in place. The thing with pouring bricks in place is that, when you remove the forms, there is a space in between two bricks, where the forms used to be. We solved this by attaching two extra pieces of wood, 6” tall, to the middle underside of 2 opposing sides of the brick form. We call them T bricks, and we used for our form a wooden, box-like form, 12”x12”, 6” tall.

Set up the forms on the wall.

Lay one level of bricks. Then, on the next level, shift the brick forms over 6” so that the l part of the T covers the gap of the level below.

- Set up a canvas tarp on the ground (about 5’x5’).
- Have buckets of water and a bag of cement handy.
- Put 27 shovels of dirt and 3 shovels of cement (9:1) onto the tarp.
- Mix the two together while it is still dry.
- Pull the edges of the tarp towards the center, so that the dirt is left in a pile.
- Hollow out the center, and then almost fill it with water.
- Scoop dry dirt from the sides into the pool of water until the pool is covered over and looks like a volcano.
- Jump into the volcano (we started using old boots after the water started getting cold, and our feet were torn up by small rocks) and start stomping.
- Sprinkle water over the dirt and pull one side of the tarp towards the other side, making the dirt roll up together.
- Stamp again and repeat the process until there is no dry dirt left and the mud sticks together.
- You don’t want it too sloppy. Cookie dough consistency is what you’re aiming for.

For the first day, we would use a paintbrush to paint on water. This helps join the mud at the seams. If small cracks appear while the mud is still a little malleable, use your thumb to mush the mud together around the crack, and then paint it with water. We then spray on water for a couple of days, a few times a day.

Small cracks are no big deal. You can patch them with adobe or just plaster over them. Larger cracks that keep growing are a sign of a more serious, structural problem (like the wall is leaning).