The best way to control top and base of the Wall is to modify the Constraints and Offset Parameters in Properties dialog.
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.1.0.0 (26.1.0.34)
Syntax
C#
public static FailureDefinitionId ShouldAdjustWallParameters { get; }