When you approach a rammed earth home, you might notice faint lines on the outside. These lines show where each level of earth was rammed. You also might notice that the exterior isn't all one color. It wouldn't be jarringly different, but there might be some slightly lighter or darker places on the wall. The owner could have covered up this imperfect wall with stucco or tile, but most rammed earth owners seem to prefer the unusual look of the house.
When you step inside the house, you'll probably note how thick the walls are; rammed earth walls usually run between 18 inches and 24 inches (46 cm and 61 cm) [source: Easton]. The thick walls add to the home's general feeling of quiet, warmth and comfort. One homeowner compared entering her rammed earth walls to a hug from a loved one [source: Lund]. But these walls provide many other benefits as well.
For one, rammed earth walls contain excellent thermal mass. If you're visiting a rammed earth home in summer, you'll find the home to be nice and cool during the daytime, without the aid of an air conditioner or fan. If you're staying overnight, the home will begin to warm up as it cools down outside. This is due to the thermal flywheel effect. The walls hold in warmth and exude it about 12 hours later.
It's not entirely the walls' doing. Rammed earth home design should factor in the natural elements that will affect the warming and cooling properties of the home. Passive solar design takes into account the sun's different positions throughout the year. For example, in the winter, southern-facing windows welcome the sun, while overhangs will shade these windows in the summer [source: Branch]. When done right, a rammed earth home will use only one-third as much energy as a conventional home, saving on energy bills [source: Whipple]. In cold climates, insulation can be added to rammed earth walls to improve their warmth.
The thick walls of rammed earth homes are also extremely fire-resistant because there are no flammable components in the earth. In addition, everything has been packed so tightly that there's little chance of combustion. In Australia, rammed earth walls have achieved the highest fire ranking available, withstanding a fire for four hours [source: Sirewall]. The walls are also rodent-resistant because they don't offer any food sources for insects or other vermin.
When completed, rammed earth walls can be left just as they are, or they can be finished with plasters, paints or siding. If left unfinished, the earth provides a natural, breathable wall, in comparison to artificial sidings with chemicals.
Other than the walls, you might not even be able to tell you're in a rammed earth home because in most other ways, it resembles a conventionally built house. The foundation, roof, electricity, plumbing and decorative features are installed in the same way as other houses.
On the next page, we'll take a look at the disadvantages of rammed earth construction.