After a couple of months my life is completely changed. Now I work in Qatar for an MEP company and I'm involved in the Red Line South Metro Project. I'm coming back with a very simple but interesting definition for Dynamo. Basically is composed by two different definitions: the first definition search for intersections between pipes, duct, ceilings and wall (could be improved with other categories) the second definition put a rectangular void, around the clash You need to load two families inside the project (you can find all the families and the sample project at the end of the article): clashSphere and voidCutter . Then open Dynamo and start first clashSphere.dyn then voidCutter.dyn . Fix the cutting issues and check again loading clashSphere.dyn or with the standard Interference check tool. Files download