Written by Vince Wheeler

Building An Earthship

The concept of Earthships was created by architect Michael Reynolds. The concept started to come into it’s own in the 70’s. The basic concept is to pack old used tires that most shops pay to haul away. Each tire becomes a rammed earth brick cased in a rubber steel-belt tire frame. This is commonly done with a sledgehammer, but modern tools such as pneumatic tampers or even hydraulic presses can be used.

Foundation

Each Earthship design starts on level ground with a foundation. There are a couple options for foundations. Some people use a rubble trench, but the most common method seems to be concrete. I’m assuming a lot of that has to do with the challenges of building to code and reselling your Earthship. Mr. Reynolds has state he’s been sued several times by people who’ve purchased his Earthships in the past. Some people have even built them on bedrock without a true foundation.

What is a rubble trench foundation?

A rubble trench foundation is built using rocks or broken concrete (urbanite). The concept of building a house on rock has been around for thousands of years. The Bible even mentions building your house on rock, not sand. In modern times it was reintroduced through Frank Lloyd Wright, who wanted to help reduce the high demand concrete placed on natural resources. Making concrete is a massively energy consumptive task. Fuel, large trucks, and other resources are used to extract the rock (aggregate), dredge and haul sand, and even burning of limestone to extract the calcium. Almost ever step in making modern concrete requires resources. By reusing concrete or simple using rock, a rubble trench helps minimize this demand.

A rubble trench is also useful in helping drain away water from a foundation. Most trenches require the soil to be excavated below the frost line. Even if your area doesn’t freeze enough to worry about this, it’s still good practice to have a trench several feet deep. With smaller 1-1 ½ inch rock placed at the bottom, then larger “rubble” being placed up to grade. A concrete bond beam can then be added to bring the building above ground level. This will help protect the natural building materials from getting damaged in heavy rain or light flooding. The trench should have a slight grade leading away from the house. There are a variety of ways to make a rubble trench. This is just an overview.

Building Your Exterior Walls

AKA: Hammering dirt into tires over and over again until you hate the sight of tires and a sledgehammer in the same place. When you pack a tire solid with dirt, it’s hard to image a more sturdy brick. Each packed tire weighs over 300 pounds. An average Earthship will have more than 1000 tires. That means your walls will weigh more than 300,000 pounds (150 tons) or 136,363 kilos (for our non-American friends). That is insanely heavy. I doubt the strongest winds would stand a chance and blowing your house away!
Michael Reynolds recommends placing the excavated dirt from the building site in the middle of the planned building. This will help reduce the distance needed to move dirt from your pile to the tire being pounded. Each tire will typically require two wheelbarrows of dirt. That’s an average of 2000 loads being moved around. Save your back and use this this tip.

How do I get tires to build an Earthship?

Getting the tires should be really easy. Go to a tire shop and ask for their used tires. Most tire shops pay $2-4 a tire to “dispose” of them. Basically shoving them into the ground at some landfill. When you get your tires, be a little picky. Not just any tire will do. If you’re someone who needs detailed instructions to build, you should buy plans from Michael Reynold’s company. A side benefit is you get to officially call your home an “Earthship” since the name is trademarked. Basically, you need larger tires on the bottom and progressively smaller tires as you move up the wall. You’re walls need to be cantilevered outwards to hold back the dirt berm being built around the building. The dirt surrounding your building can be 15-20 feet thick and is compacted as well.

Using The Same Water Four Times

Earthships are designed to allow your roof to work as a rain catchment system, gathering the water and storing it in cisterns buried in the dirt berm behind your home. The premise of Mr. Reynold’s design is to reuse the water four times. So 5,000 gallons of water is essentially 20,000 gallons.

Using water four times when water is in short supply is a great way to build a home that will sustain life. For every inch of rain over a 2,000sqf roof, you’d add 1,247 gallons of water (for our non-American friends: 25.40 mm of rain over a 185.8061m² roof will produce 4,720.1 liters of water).

First Use:

The rain water is used for drinking, food preparations, and dishes. Since the water is the most pure right from the sky, you only need to do basic filtering to make it consumable. Some people use Berkley filters, but I suspect almost anything that removes the random bird poop and twigs will do just fine.

Second Use:

Then the water moves into the front garden area where it is treated by nature. Mostly filters and plants. Plants naturally clean water and the water isn’t used for consumption after this part of the system anyway. This water feeds your plants that feed you and from there it goes towards uses that don’t need to be consumable. In theory most of your vegetables would come from this garden, but. honestly almost all the examples I found have very little edible vegetation. Maybe enough for a salad or some herbs, but not enough to sustain life. It’s a neat idea though. A more recent design called the “Phoenix” is incorporating two greenhouses and a which is going to make it much more likely someone could grow a substantial amount of their own food supply

Third Use:

From there, the water is pumped to your toilet. With the plants in the garden cleaning the water, it doesn’t have a smell and looks perfectly normal. Your toilet doesn’t mind if it’s not potable.

Fourth Use:

After you flush your toilet, it then goes into a septic system and leaches out into a green area in front of your Earthship. This feeds and waters plants that would otherwise have a harder time growing in the arid environments many Earthships are found in.

Earthships are one of my favorite building styles. The modern designs are absolutely beautiful. Personally, I don’t think my body will stand up to pounding thousands of tires full of dirt without causing some type of damage to my shoulders or back. I have considered building an earthship using gabion walls. I think it would allow older people a chance to have an earthship without all the tire pounding. If your land has a lot of rocks, even better. You can kill to birds with one stone!

The concepts of earthships are hard to beat when it comes to off-grid, thermal mass regulated, building designs. I’ll leave you with a video of one of Michael’s newest designs. I personally love it.