Attach columns to floor

Hi all,

I started useing dynamo a few weeks ago thx to some colleagues.
Now i am trying to attach all columns in my project with there base to a floor 15m below surface, only i cant find a attach function in dynamo. What package do i need to download for this function or do i need to do something different?

Assuming that the base floor is level, you can attach by altering the Base Level (or Base Offset) property of the columns.