Finished bottles. Remember, one’s trash is another’s treasure!
Last year I worked on making cob walls for a chicken coop, after attending a natural building course over a weekend which taught me about bahareque, the Central American equivalent of cob, if you will, which is adapted for tropical climates and for heavily seismic areas. The teacher, Eduardo Valverde, who is a Costa Rican green architect well versed in natural, indigenous and mud-based construction techniques, combines ancestral knowledge and skills with the reality of our polluted world. He introduced the class to the idea of plastic bottles stuffed with trash such as candy wrappers, plastic bags, etc. He called them ‘eco-bricks,’ and explained that they are often used in green construction, either by themselves or in combination with mud and cob.
After learning how to make them, I took the knowledge back home and enlisted the help of my friends for the admittedly slow-going process of stuffing the bottles. After several weeks of work, we had amassed around 70 sturdy, plastic-filled eco-bricks. In developing countries where recycling is not the most efficient, making eco-bricks allows for the reutilization of those pesky, noisy candy wrappers, which are most often made out of cellophane, a material which is not always recyclable.
I’ve written down some pointers regarding eco-bricks that I would like to share in hopes that more people can learn how to make them, their properties, pros and cons, and what to use them for.
Once the bottles were stuffed, they were used as ‘bricks’ embedded into the cob walls.
Making eco-bricks is simple enough, and there are only a handful of things to be aware of. The most important thing is to make sure you thoroughly wash and dry both the bottles and the trash you will be stuffing into them, to ensure that there is nothing organic inside the bottles that could rot or decompose. Several months after the completion of the cob walls, I was able to inspect and break apart a section of wall, and did notice that one or two bottles had water inside of them, and others started to grow fungi. While not a terrible problem for a small project like a tool shed, wall or low chicken coop, I was told to be mindful of this issue by my teacher, who explained that enough faulty bottles could compromise the integrity of the structures you were building.
When you have your materials prepared, simply look for thin sticks or construction rods. You need them to be thin enough to fit into the bottle, strong enough to handle constant strain, and long enough that you can push your stuffing material all the way to the bottom of each bottle. Once you have everything you need, you can start stuffing! It’s almost ludicrous just how much trash can fit into those bottles. It’s very important to stuff them with as much material as possible, so that your end product is a light, but extremely hard and sturdy brick. It is also tricky to get them just right, since shaking the bottle or moving things around will suddenly reveal more space which needs to be stuffed. After making a couple of bottles, though, it is easy to get the hang of it and, although tedious, the activity can be turned into something fun to do in groups. Just be sure to tightly cap each bottle at the end to prevent water from entering or escaping them.
One of the biggest advantages of eco-bricks, apart from their truly incredible strength, is that they can provide precious ‘bulk’ for building in situations where, for example, you don’t have a lot of mud to work with, or have nothing else to build with. I used them by lining an initial layer of mud with a layer of bottles, and so on. There is also the option, as you will see below, of using only bottles to build. However, it is important to keep in mind that, since they are plastic, the bottles will interfere, to an extent, with cob’s ability to thermoregulate and, as a porous and earthly material, pass humidity through its walls like a permeable membrane would. I did experience a section of wall getting very wet as a result of a bottle that had not been capped and had started to form condensation inside it. Keep in mind, though, that this is the tropics, where almost everything will, at some point, sweat like a pig. I have heard of people in drier climates using them with great success, as is the case with Earthships, which are sometimes made using plastic bottles.
Another con of using eco bricks is that, if you leave the bottles exposed to UV light, certain kinds of plastics can begin to rapidly degrade. Most people will cover them with cob and other materials as plastering in order to prevent this. Speaking from personal experience, I also noticed that, perhaps due to the bottles expanding and shrinking with heat and humidity, they would move and even crack the mud closest to them. It might be best to avoid using them close to the outer surfaces of your walls.
Eco-bricks are used all over the world, seeing that there is an overwhelming amount of non-recyclable trash and plastic bottles polluting our environments. Head on over to an article by the Plastic Pollution Coalition for more information. Also check out ECOTEC Africa, for their PET-bottle based construction as shown in the video below.
Some of the students present in the cob-building class didn’t seem to take to the idea of having their walls lined with ‘trash’. I think that we should have deep discussions on this topic, and, personally, I see eco-bricks as a great way to take responsibility for the trash that we already produce. They are readily available, can be made for no cost at all, and open up possibilities for countless, exciting DIY projects and social and environmental activism. Recycling is often a process with a heavy ecological footprint, so reusing and upcycling these waste products all around us in creative and positive ways is not only a good option, but an imperative.