Down and dirty, but green

EARLY one Saturday morning in January, Kevin Rowell dumped a bucket of dark mud on the floor of his big south-facing bedroom.

EARLY one Saturday morning in January, Kevin Rowell dumped a bucket of dark mud on the floor of his big south-facing bedroom. It landed with a plop, spreading out and merging with a blanket of wet earth that already extended across much of the room. On his knees, Rowell took a trowel to the pile, nudging it this way and that until the mud was roughly level and about an inch and a half deep.

As Rowell finished smoothing that section, his wife, Marisha Farnsworth, appeared at the door and handed him another bucket of mud. The mud would soon cover the entire floor .

8220;It8217;s beautiful,8221; said Rowell, 28, as he stood back to take in the whole room. Rowell and Farnsworth, 26, were working with a dozen friends to install a dirt floor in their newly purchased 50-year-old home in this Oakland suburb.

The floor8212;which, in addition to the basic ingredient, included lime and sand, two classic components of concrete8212;would take a few weeks to dry. But once sealed with a mixture of linseed oil and beeswax, it would theoretically be firm and water-repellent. Fans of such floors say that soapy water will clean them without turning them to mud, and that another coat of oil can renew the shine.

The couple are part of a new breed of environmentally conscious homeowners who are willing to forgo traditional floorings like hardwood, carpeting and concrete for the supposed benefits of earthen floors: a reduction in heating costs and environmental impact and, at least in the eyes of some, an improvement in looks.

They are part of a small movement interested in 8220;natural building8221; on the fringes of green architecture. But they consider green architecture to be overly focused on energy efficiency, while they are concerned with the eco-friendliness of the entire process. The idea, according to Lloyd Kahn, a former shelter editor of the Whole Earth Catalog, is to use 8220;materials that have as little processing as possible, like dirt, straw and bamboo.8221;

But lest anyone get the wrong impression, dirt is neither easy nor trouble-free. In a lot of places, the dirt often 8220;cracks horrendously,8221; said Bill Steen, a natural builder in Elgin, Arizona. Steen and his wife, Athena Swentzell Steen, have led an effort to modernise the techniques, adding sand and fibre in carefully calibrated amounts to control cracking.

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For natural builders, the most practical benefit of earthen floors is thermal. The high density and low thermal conductivity of an earthen floor allows it to capture and retain warmth. Some builders install radiant heating systems in their floors, which circulate hot water and reduce the need for conventional heating. And when the floor receives direct sunlight it can act as a passive solar device, absorbing heat during the day and releasing it at night.

Earthen floors are not right for every room in the house, builder Frank Meyer said. 8220;It8217;s great for a sitting room, a library or a hearth around the fireplace, but I don8217;t recommend them for wet areas like bathrooms or kitchens,8221; he said. 8220;They are vulnerable. If you ever have a flood in your house, it8217;s going to saturate it and you8217;re going to have a big mess.8221;

Rowell and Farnsworth said that one of the most appealing aspects of the new earthen floor in their bedroom was its cost. 8220;Our material cost per square foot is about a dollar, if that,8221; Rowell said. Labour costs included, earthen floors can run as little as 5 a square foot, compared with 15 or more for hardwood.

8212;NYT / DAVID GELLES