Final answer:
Subsoil drains should always be sloped away from structures to prevent water accumulation that can damage the foundation. Incorrect orientation like sloping towards buildings or keeping the drains level can lead to serious moisture and erosion issues.
Step-by-step explanation:
Subsoil drain lines are an integral part of a building's foundation and landscaping design. It is crucial that these drain lines are installed with the correct orientation to ensure that water is efficiently removed from the area surrounding the structure. Sloped away from structures is the correct way to install subsoil drains.
This orientation prevents water from accumulating against the foundation, which could lead to water damage and undermine the structural integrity. Sloping the drains towards buildings can result in excessive moisture build-up, potentially leading to basement flooding, mold growth, and weakening of the foundation. Maintaining a level or vertical orientation would not facilitate the necessary water flow away from the building. Subsoil drainage is essential in managing groundwater and surface water, particularly in areas where soil erosion or contamination is a concern.