The program detects a clash if the value by which two objects overlap exceeds the value you entered for overlap tolerance.
Click 
Clash detection on the left sidebar.
The Clash manager palette opens on the left.
Check and change the default value set for overlap tolerance. Do this for the object class you want to check for clashes.
The program detects a clash as soon as the value by which objects overlap exceeds this value.
Click 
Start clash calculation.
After finishing calculations, clash detection displays the number of clashes detected for the object class in question.
Note: Clashes are sorted by status in each object class: clashes detected (red), open clash tasks (yellow) and solved clash tasks (green). You can use 
Show clashes to show and hide the clashes of each status in the model in full view.
