Feet on the Ground: Earthen Floors

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After living with earthen floors for twenty-five years, Athena Steen has grown accustomed to skeptics. Merely mention the material, and even progressively minded souls raise a brow. “Then they see it, and the first thing they do is bend down to touch it,” Athena says. “They’re shocked that it’s hard, that you can sweep it, that you can mop it, that it’s not dusty. They’re astonished that it has none of the bad qualities they thought it would have.”

No less amazing is that the floors are comfortable underfoot, durable, and beautiful. And that may explain why, centuries after earthen floors were last considered standard home decor, the most natural of natural floors is suddenly surfacing in eco-friendly homes everywhere.

Athena grew up in a house with earthen floors, thanks to her mother, who studied architecture and supported earth-friendly practices long before such ideas were commonplace. “I loved that house because it had such character,” she says. “The floor was warm and soft, not like concrete. If you dropped something, the floor would give before anything broke.” Not long after her family laid the first floor, neighbors asked for help in crafting their own. Twenty-five years later, the original floor remains intact. “My mother had to reseal it a couple of times, and she keeps clay handy to patch the occasional cracks,” says Athena. “Someone with an untrained eye can’t even tell there ever was a crack.” Today, Athena and her husband, Bill, are well known in natural building circles for their booklet, Earthen Floors, which has drawn a steady flow of readers since they first published it in 1996, and which they have just revised.

“At our house, we have a thin floor in the kids’ room where it gets plenty of abuse. In ten years, I haven’t had to do anything to repair it.”

Environmental and economical

Earthen floors are hardly new, of course. From the earliest times, people have used earth to form home floors. In the American Southwest, ox blood was mixed with the dirt for a stronger, more durable surface. For similar reasons, rural Japanese poured bath water, which contained oil from the bather’s skin, onto the unsealed floors. In India, ghee or clarified butter was used.

The ingredients in contemporary earthen floors vary according to region, but in North America, they generally consist of water, soil with clay content, sand, and chopped straw. The mix is then poured, troweled into place, and sealed with linseed oil after the floor has dried. Other factors, such as insects, radon, drainage, and temperature, determine the use of subfloor materials and insulation.

While fans sing the praises of durability, beauty, and comfort, earthen floors would barely warrant a second glance if it weren’t for one additional attribute: They are just about as eco-friendly as building material gets. Robert Bolman, a Eugene, Oregon, builder, recently made local newspaper headlines when word of the earthen floors in his urban home and rental properties spread. Bolman, who learned to make the floors under the Steens, says they exemplify the natural building ideal.

“One of the central intentions of natural building is that when your house reaches the end of its lifespan, the lumber and hardware get recycled, and the majority of the building material simply decompose,” he explains. “Rain and microorganisms will break down an earth floor in a relatively short time–probably within a few years. It’s a truly cyclical process.”

Earthen floors are also economical if you do them yourself. The soil, if taken from the home site, costs nothing, and sand is inexpensive. The biggest costs comes from the natural linseed oil, which is about twelve dollars a gallon off the shelf and much less in bulk. Bolman used 12 gallons for his 450-square-foot home and 55 gallons for the downstairs floors in his 3,400-square-foot triplex.

The drawbacks

Though functional and sustainably viable, earthen floors have a few disadvantages, including odor from the sealant and problems with scratching and cracking. Fortunately, the Steens say, these difficulties can be overcome.

Like most conventional floors, earthen types must be sealed, and some linseed oil can leave a lingering odor. To combat this odor, the Steens use raw linseed oil; while it takes longer to dry, it has only the odor of flaxseed oil (raw linseed oil is derived from extracting oil from the seeds of the flax plant and is used, in this unprocessed form, as a nutritional supplement). Boiled linseed oil, made through processing raw linseed oil, has additives that produce strong toxic odors, but using it also hastens drying time. To avoid these fumes and to speed drying time, the Steens pre-oxidize raw oil by placing it in a shallow container in the sun.

Unfortunately, earthen floors are not indestructible. Dropping a brick from chest height, Bolman says, would likely dent an earthen floor, but the same could be said of a wood one. “It’s more comparable to a slab of leather than concrete,” he explains. Which means, says Bill Steen, that earthen floors are sensitive to scratching. “It doesn’t mean they aren’t durable, but people can’t have unrealistic expectations.” In areas with high foot traffic–under a desk, for instance, or in an entry way–earthen floors may not perform well or may need to be sometimes supplemented with alternative materials such as flagstone or brick. Chairs, sofas, tables, and other furniture may need padding underneath their legs to disseminate the concentration of the weight.

The Steens have improved on tradition by making their earthen floors thinner than usual. “Most traditional floors in Mexico are three to four inches thick,” says Athena. “It takes a long time for the earth to dry, and during that process cracking is bound to occur. The more cracking you get, the more vulnerable the floor will be. So, we pour thin layers to reduce the cracking. A half-inch layer provides all the strength you need.” This half-inch layer, though, rests on a three- to four- inch layer of clay, sand, and gravel or crushed stone. If you pour this supportive layer in a damp state–and even add lime to the mixture–it will dry and harden more quickly. “At our house, we have a thin floor in the kids’ room where it gets plenty of abuse. In ten years, I haven’t had to do anything to repair it,” Athena says.

Getting a permit to lay earthen floors may also present a few hurdles. In Bolman’s area, city engineers were reluctant at first. “I made a one-square-foot sample and handed it to the code analyst,” he recalls. “He set it on his desk and poured Coca-Cola on it, then went home for the night. The next day, the Coke had not soaked in, so my floor passed the acid test.”

No matter how you look at it, laying an earthen floor is one labor-intensive home project. “It’s hard work extracting dirt, sifting it through the screens, running it through the machinery to mix it, pouring it, and then smoothing it with a trowel,” Bolman admits. “You can put even more labor into it by burnishing it to try to make it really smooth.” Bolman did, however, come up with a time-tested and true solution for the amount of required labor. “I hosted a work party. You make a big pot of chili and invite a whole bunch of friends. It’s very helpful.”

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