 The soil-covered roofs help incorporate the environment, protect the natural scenery, and contribute to the oxygen-nitrogen balance of the soil, which would otherwise be covered by the foundation of a traditional house, inhibiting nitrogen fixation and aeration of the soil.Contrary to conventional roofs, earth-house roofs restore usable surface area to the environment.They can also be built as terraced structures if the slope is appropriate, thus using far less land area, because the structure can be built right up to the property boundary.