Earthen Building: Why and How-To

There are many ways that people can change in order to relieve the burden of destruction from the shoulders of the environment. More efficient electric cars are being produced, wind farms are popping up all over the place, and small, organic gardens seem to be taking over grassy lawns. What seems to remain neglected in the sustainability conversation is construction.

The process of constructing homes takes a major toll on the environment. One fourth of the wood in the world is used for construction, which means a lot of clear-cutting, the drywall lining the walls of most homes produces CO2 during its fabrication, oh, and don’t forget all of the indoor pollutants that come from combustion sources, building furnishings, and household cleaning products.

It seems as though, even in our own homes, we’re forced to enjoy luxuries that come at a high cost to the health of our planet and even to ourselves. However, some refuse to accept the white-picket American dream house of suburbia and instead go for something much more down to earth. Mud home construction (or earthen building) has a very small impact on the earth and requires fewer resources than most other form of construction. It may seem like a new, hip way of showing devotion to environmentalism, but in reality, today’s earthen buildings are reflections of ancient construction with contemporary aesthetics. But any way you look at it, one question remains… could you live in a mud house?

Building with cob is the quintessential earthen construction experience. Cob is a mixture of clay, silt and straw which is formed into softball sized balls, then stacked like bricks in order to create strong, insulating walls. Aside from the jobsite basically being a mud fight, cob is traditionally mixed on a tarp by a group of people stomping around in their bare feet while buckets of sand, clay, water and straw are thrown under them. Once a wall is constructed, it is a clean, smooth, blank-slate for sculptors and artists alike. After the walls are sealed with natural oils, they are able to withstand the elements while remaining aesthetically pleasing.

Rammed Earth
Rammed earth construction involves the same mud/sand/straw mixture as cob, but without the mashing together of muddy bricks. Instead, temporary molds are built for the walls which are then filled in with the mud mixture which is then tamped down. Rammed earth walls are usually quite thick and have an incredible insulation value, but are labor intensive if done without the help of mechanical tampers. If you want your friends to help you out with your earthen home, cob might be the better route. But if it’s fortification you’re looking for, rammed earth is your best bet; parts of the Great Wall of China were even built with rammed earth.

Straw Bale
Perhaps the simplest way to put up the foundation of you house is by using massive, lightweight bricks. Straw-bale construction is exactly what it sounds like; Bales are stacked on top of each other and fastened together with wire in order to create the walls which will bear the entire load of the roof. The beauty of straw-bale construction is in its simplicity; it is nearly measurement-free and the bales provide a great insulation. However, the bales must be sealed in order to prevent rot or deterioration by natural forces. The first straw-bale house was built in 1896 in Nebraska. By 1902 it had been completely eaten by livestock. An earth-based plaster is commonly used to seal the bales and keep them from being affected by the elements (cows). In the world of natural building, straw-bales tend to provide a more contemporary look; perfect for the closet hippie in all of us.

Although earthen structures are very effective when built right, they need to be maintained and cared for properly in order to keep from deteriorating into ruins. Walls must be sealed in the summers, structures must be elevated on rock foundations, and if you don’t mix you mud correctly, your walls will crumble. Still, the construction is relatively simple, even for do-it–yourselfers and they payoffs of health, creativity, and a small carbon footprint can go a long way. Not everyone is going to understand your new hobbit-like habitation (especially if you go for the grass roof), but let’s face it, everyone’s going to want to come to your mud-stomping parties.

By Robin Johnson