Create filled region in section/elevation view from room location

I want to create a view to indicate where an apartment is located by overlayering a filled region on a facade drawing(look right corner):image

I was thinking about doing this by makeing a section line and find where it intersects with rooms.
But i have used a model line instead since I can not get the curve from the section line:.

Then get or build a curve for the rooms crossed by the section, draw the curve as a filled region in the section view and copy the filled region to a facade view

However i dont know how to get a room boundary in a section view,

So how can i do this and get a curve from a section line?
I can not get view plane of section view