Cast Earth Green Home Innovations: Cast-Earth Walls - Homes Across America Search Return

Cast Earth Green Home




Goals of Innovation: To provide a unifying central design element adding beauty and interest to the home while achieving thermal efficiency and balancing.

Description: A central two-foot thick wall of cast-earth runs the entire length of the main floor separating the main living areas on the south side from secondary or back of house spaces on the north side. Every space on the main level has an exposed section of cast-earth wall for thermal mass and tempering of the space. Paul Speck with Cast Earth Homes in Greeley, Colorado installed the cast-earth wall in this home.

On hot low 90 degree Fahrenheit summer days, the interior spaces maintain a constant 70 to 76 degree temperature due to this thermal mass. Windows are mostly closed during the day and opened at night to augment this system design. The wall is structural, holding up half the lower and upper roof loads and half of the second level floor load. It is a beautiful centralizing design element of the house. It emulates a cut through of a riverbank.

The wall was installed after the foundation walls were poured and before framing. Concrete slabs were poured later.

Obstacles: This is a new type of construction with only one other in the state. It took some time to educate the local building official and local testing lab on how to properly test samples. The local building official required the testing. The structural engineer specified the wall needed to be 200 pounds per square inch (psi) and the wall tested from 500 psi to 1500 psi. Walls were needed before the framing could proceed and it was best for other trades to stay off-site during the construction of the walls.

Cost Information: This wall was about the same cost as concrete. More than frame construction. Using it for structure added cost benefit. It is hard to calculate the thermal benefit of the wall, but it definitely contributes to the thermal efficiency and comfort of the home and a reduction in energy use. It uses gypsum as the binder and is therefore more environmentally friendly than concrete, which uses cement.

Additional Benefits/Drawbacks: Thermal benefits are great. This innovation met and exceeded the expectations and project goals. Computer modeling of utility cost is projected to be approximately $30 month as a high for heating.

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