Hard Clash vs. Soft Clash in BIM

In BIM coordination, clashes fall into two broad categories, and distinguishing between them is central to prioritizing coordination work. A hard clash is a direct physical intersection between two elements — a structural beam occupying the same space as a duct, pipe, or conduit. Hard clashes are unambiguous: something has to move.

A soft clash, sometimes called a clearance clash, doesn't involve physical overlap but violates a required buffer or access zone — insufficient clearance around a valve for maintenance, inadequate space for insulation on a pipe, or a fire-rated assembly without its required clearance envelope. Soft clashes require judgment: what clearance does code, the manufacturer, or the facility's operations team actually require?

Both categories need a resolution path, but they're not equally urgent. Hard clashes on primary structural or major duct routing tend to drive early coordination decisions because they affect the most other systems. Soft clashes are often resolved later, once the general arrangement of major systems has settled.

A coordination process that treats every clash the same way — one long undifferentiated list — buries the conflicts that matter most. Classifying by trade, severity, and constructability impact is what turns a clash report into a workable coordination plan.