I'm trying to draw a roof with no success.
These areas should be filled that I can add roof texture there. I tried with sandbox and "from contour" but it's not what I want (can't use a tile texture on it).
What you need to do is create a plane. Planes should be automatically created, but if they are not, its a good idea to draw a line from corner to corner to force a plane to be created. Once a valid solid plane has been created you should be able to use material fills.