One of my clients was asking about drawing a stone capping on a wall. There are two ways to deal with this, drawing a 2D plan view, or correctly modeling the stone capping in 3D. This applies to more than just a stone capping, it applies to any wall that has a capping on it.
You have to decide what you want to show, the 2D only, 3D only, or a combination of both.
If you want to show 2D only, then use a wall style.
If you want to show 3D only, then create the wall, then model the capping in 3D using an extrude, or Extrude Along Path, if the wall has changes in direction.