Revit LT includes a Stacked Wall system family for modeling walls that comprise 2 or more subwalls stacked on top of each other.
The subwalls can have different wall thicknesses. All the subwalls in a stacked wall are attached and their geometry is joined.
Only wall types in the Basic Wall system family can function as subwalls. For example, you can have a stacked wall comprising an Exterior Brick on Metal Stud and an Exterior CMU on Metal Stud that are attached and joined.
Using stacked wall types, you can define different wall thicknesses at different heights. You define its structure using Type Properties.