Making separate component based on a rectangle

In the Sketch up fundamentals, Getting started 4, Components, a playground is made. When a pillar is formed with the rectangle and push and pull tool, it remains a separate object which can be selected and grouped to a component. When I make it (with Sketchup free web), it becomes one with the roof and I cannot select it separetely anymore by clicking three times. So I cannot group it. What to do?

Make the roof a group or component first. Then if you don’t open it for editing, you can draw your new rectangle on it and it won’t bee connected.