A lot of users are not using every physical layer in compound objects like walls, floors and roofs. Plaster is a good example. While some will add plaster in their wall definitions as a finish layer to get accurate room area’s and material takeoffs, others won’t because the plaster layer is too thin and this would cause problems on their print-outs (on a scale of 1:100 you could get one thick line instead of 2 thin lines). Another reason of not including the thin plaster layer is because a lot of users want to add dimensions on the core layer, and this is difficult when there is a tiny layer just next to it.
In the past one solution was to add a membrane layer with a zero thickness in your wall definition, using a “Plaster” material.
But when you tried to use the same technique for floors and roofs you got a an error: “Face layers must have a thickness”.
It seems that in Revit 2018 you can now, for floors and roofs, also use membrane layers for the face layers:
But still there is just one remaining problem: visualization is not consistent….
Example: walls and floor do all have a face membrane layer using a red material appearance. In your views and renderings only the membrane layer of the floor is visible, not the membrane layers of the walls.