If you don’t like the organic curves of cob walls, you’re in luck – you can also choose a modernistic rammed earth material with rectangular edges and straight, flat walls. There isn’t just one type of earth masonry – there are several flavors to choose from, such as cob, adobe, earthbags, straw-bale, and rammed earth. So you can take your pick, and design your natural building just for you.
Cob is one of the most popular natural building materials, using soil, clay, water, and straw. Modern-day cob structures take on a new creative form, boasting smooth and curvy wall design, decorated with upcycled glass, colored stones and rocks, and even earth paintings. Cob walls adorned with glass mosaics are incredibly beautiful, as are the addition of stained-glass windows.
The great thing about cob is that it is one of the simplest forms of natural building, requiring no baking, no bricks, no formwork or structural molds. One of the most popular cob structures found on permaculture sites is the cob pizza oven. It’s a great way to showcase what cob can do, and it cooks pizza in literally just 2 minutes!
Adobe is like cob in that it is made from sand, clay, water, and straw, but differs in that it is shaped into bricks (using frames) and baked or dried in the sun. Adobe buildings are extremely durable and account for some of the oldest buildings in the world. Since bricks are used in adobe buildings, there is less use of curved edges. But decorative pieces can still be imbedded into individual bricks.
Earthbags contain a mix of soil and straw in a grain bag, and are stacked on top of each other like bricks. They are covered in adobe or plaster to shed water and prevent any damage from solar radiation.
Rammed earth is more complicated, as it requires formwork (a structural mold). A damp mixture of sand, gravel, and clay is compressed into wooden frame or mold, creating either a solid wall of earth or individual blocks. Lime can be added as a stabilizer.
There are many astounding natural building projects around the world today, both ancient and modern. Our modern building codes have yet to understand or accept natural building, especially considering the low profit margin available to the construction industry. And yet, people all over the world are continuing to take interest in this sustainable building method, allowing the information, technology, and culture of natural building to flourish against the powers at large.