Now that I had the basic concept of Earthships rooted in my mind, I began to do some digging on their materials. One thing that piqued my interest was the construction of the walls! While it was apparent some modern methods were still used, the method of upcycling really caught my eye. What exactly was it about these materials supplements that worked for the structure? I decided to do some digging and try my hand at building an Earthship this past Sunday. What follows should illuminate your imagination a little bit.
Plastic Bottle Bricks. Sounds simple enough, and simple it is! Plastic bottles are among the many industrially indigenous materials to every region of the earth. They come in all sorts of colors and shapes. Once stuffed to the brim with plastic bags they are stacked in staggered lines layered with cob to build a wall. I investigated and found an article from The International Association of Advanced Technology and Science*1 that found these walls to be 20 times more structurally sound than normal brick walls. So what about the other brick replacements?
Glass Bottle Bricks. Those three words might stir up a scene of a bar fight, but I assure you it’s something quite more beneficial. Used not just for structural strength and heat retention, but also as a means to beautify. I discovered last Sunday at the Seattle Earthship build that you do not just shove a glass bottle in the mud and repeat. You want to collect like colors so that you can cut off the necks and duct tape them together. Filling them with liquids is not advised*2
Beer Can Bricks. Same principle applies as with the plastic bottles mentioned earlier; only they do not have to be stuffed with plastic bags. The metal void both reinforces the concrete and serves as an air pocket for insulation. Once stacked these walls are given a face coat of cob/mortar and sometimes plaster. Using these materials means you spend less on your mortar or cob mix.
Cob – This is a term some of you may not know about. It is a natural alternative to cement or mortar mixes that has been around for thousands of years. The basic principle is to mix sand and clay together with a binder to create a stone-like material. Binders come in the form of straw, plant fibers, and even hair. Mix until globby: not too runny, but not dry. The cob secures and weights down all the bottle/can bricks you have laid then essentially turns to stone.
I was able to experience this past Sunday at the Earthship Seattle build and had a great time! Florian guided the attendees thru what to do to finish a glass bottle wall. Some of us worked with sifting clay and making cob, while others set bottles in place and lay cob in a fashionable manner. There is still much to be done there, and with regular workshops there is plenty of opportunity for YOU to come participate (for those of you interested*3). See you all next week! – Seth
*1 Plastic bottle Brick Study – http://www.jiaats.com/Journals-Pdf/March-2015/jcme/Jcme-12.pdf
*1 Glass Bottle Bricks – http://earthship.com/blogs/2015/01/make-bottle-bricks/
*3 Earthship Seattle FB – https://www.facebook.com/EarthshipSeattle/?fref=ts