The best way to control top and base of the Wall is to modify the Constraints and Offset Parameters in Properties dialog.

public static FailureDefinitionId ShouldAdjustWallParameters { get; }

Public Shared ReadOnly Property ShouldAdjustWallParameters As FailureDefinitionId
	Get

public:
static property FailureDefinitionId^ ShouldAdjustWallParameters {
	FailureDefinitionId^ get ();
}