Cannot separate roof from pillar

No line at top of pillar
Pillar connected to side
I was having trouble with SketchUp. So, I took a 2 week break and am starting at the beginning again.

See the picture. I made a roof and am trying to make a pillar. When I tried to make the pillar into a component, the roof was part of the component.

Why is there no line separating the pillar from the roof?


Because of the sticky nature of the geometry in SketchUp. Since the roof geometry is still ungrouped, adding more geometry in contact with it results in that new geometry joining with the existing geometry.

Make a component or group of the roof before you draw the rectangle for the post.