MEPSection Roughness Property |  
 The roughness of the section. 
 Namespace: Autodesk.Revit.DB.Mechanical
Assembly: RevitAPI (in RevitAPI.dll) Version: 25.0.0.0 (25.0.0.0)
 In one section, all section members have same roughness. Default unit is Decimal feet. For Duct, unit type is UT_HVAC_Roughness. For Pipe, unit type is UT_Piping_Roughness