Wednesday, April 12, 2006
A Rammed Earth House Near Chapel Hill
I've been researching rammed earth houses today, and reading over an interview I had with home owner and real-estate agent Gary Phillips near Chapel Hill. He built a rammed earth house with a little help from his friends. It's a beautiful two-story cottage that I would never guess is made from soil. The surface of his outside walls is not painted, plastered, or stuccoed. It's just a smooth light-brown surface. If I didn't know what it was, I guess I'd think it was some kind of tinted and slightly textured concrete. It's that smooth and even. Gary's rammed earth walls are 2 feet thick.
When I visited his house, he explained to me that each wall is made by pouring soil with a front loader into a concrete box made of two 8-ft-tall sheets of vertical concrete that are two feet apart. As each load of soil is dumped inside the box, a work crew gets on top of the soil and tamps it down with a pneumatic tamper, layer by layer, until they reach the top of the concrete form. The completed soil wall has to "cure" for only 24 hours! Then the concrete is moved and wall stays where it is! That's amazing to me. Gary put iron oxides between some of the layers of soil in his walls just for aesthetic reasons. The oxides leave undulating dark horizontal striations in the finished wall, a charming effect.
Sara Kate and I will be writing more about Gary's house and about other earthen building materials in our upcoming book about green consumer choices.