You’re confusing intersection with a clash.
I am sitting on a chair, but I do not clash with the chair as the chair has it’s space and I have mine (we can argue about the molecular bond between my backside and the chair created by my tendency to not walk away from work at a later date). The intersection between me and the chair is a surface, but it does not have a volume. DoesIntersect will return true if there is as much as a point of overlap (a pin stood on end on my chair perhaps), and it will also return true if the object is entirely inside the other (say the sandwich I ate for lunch). If you’re concerned with construction clashes, test the actual geometry intersection (Geometry.Intersect) when objects return ‘true’ when testing for DoesIntersect, and filter out objects which don’t create a volumetric solid.