Merge layers of sloped ceiling & flat ceiling

[dimitri.b]

Hoping its a simple one Revit gurus!!!!

Question 1) Easiest way to merge the layers of a sloped ceiling and a flat ceiling? Also the same for a sloped roof to a "less sloped" roof. See snippets below.

Question 2) What is the simplest way to set a sloped ceiling at the same angle as the stair and at 2700 high. The way I did it was draw a reference plane on the stair angle and then Move (MV) it up 2700 high. I then modelled a ceiling to the reference plane angle and then in section used Move and moved the ceiling up 2700. 

Is this the best way to do this. See snippet below.

Thank you all!!!

 

[ToanDN]

Model a roof by extrusion and reclassify it as a ceiling by changing Assembly Code.

[dimitri.b]

Thanks @ToanDN 

I also have a situation where I am trying to get the external wall adjacent to the stair visible (I'd) like it shown dashed to indicate above). As you can see from the image below it doesn't go the full length of the stair (highlighted in blue), because the wall follows the stair and is above. Therefore, when I turn on underlay, I would expect the wall above to appear. It doesn't.  

The wall was created by modelling a simple wall and then using "edit profile" to match the angle of the stair. When this tool is used, it no longer appears in the underlay settings. However, if I were to create just a regular straight wall, it appears in the underlay even if its above. There is something about when I use "edit profile" that it doesnt like.