Building PAD at diferents elevations

[agustinbarovero]

Hi, I need to generate an excavation at different stages in Revit. I need to go climbing first at a depth of 3m and then go down to 7m. 

I try to do it with building pad but it can't overlap. I would like to know ¿How  can I do it?

Thanks

[ToanDN · Accepted solution]

The -3m pad should be created in phase 1, demolished in phase 2. The -7m pad should be created in phase 2. They should share the same sketch boundary.

[barthbradley]

Can you elaborate? What do mean by "stages" , "climbing", "overlapping"? 

Illustrations might help. 

[agustinbarovero]

The problem it was in the phase of demolished.

Thank for your time.