There are several times when you need to show line work that is either overhead or hidden and not natively shown in Revit. A couple of examples of overhead lines would be the edge of slab in an atrium space, or the edge of a roof overhang. Another frequent request is showing the recess for a cove ceiling design. Both of these issues are resolved using the linework tool, which can be found under the Modify Ribbon.
To show overhead lines, set the underlay properties so you can see the elements you want to show on your floor plan. Using the linework tool, select the line style, for example , and click the line you want to show as a hidden line. You will see the line turn from light gray into a dark dashed line. If you turn your underlay off, you will see that the dashed line remains.
This same process can be used for illustrating a cove light or other hidden geometry. However, rather than using the overlay settings, you need to set your view to wireframe. This may require that you use Temporary View Properties if your sheet views are controlled by a view template.