Clash Detection in BIM: Why a Report with 4,000 Clashes Is Worth Nothing

Every BIM tool can produce a clash report. The problem: a report with thousands of rows that nobody acts on prevents zero concrete demolition. The difference between a report and a clean model is a process — and that’s what this page explains.

What is clash detection?

Clash detection is a computerized run that finds every point where elements in the model occupy the same space — a pipe crossing a beam, a duct inside a wall — or violate a required clearance. The check runs on the combined model of all disciplines.

Types of clashes

• Hard clash — two elements in the same physical space. Requires a design solution.
• Soft / clearance clash — a violated required clearance: maintenance access, installation distance, safety margins.
• Workflow / sequence clash — an impossible work order: a system that can’t be installed because something else will already be built in the way.

Why isn’t a raw report enough?

An automatic run on a real project easily returns thousands of results — most of them duplicates, negligible, or artifacts of coarse test settings. Without professional triage, the report produces noise that paralyzes the team. The real work is:

1. Smart test definitions — which disciplines against which, at what tolerances, in which zones.
2. Triage and grouping — turning thousands of results into dozens of real problems, ordered by construction severity.
3. Engineering resolution — every problem gets a proposed solution: offset, rerouting, level change — coordinated with the relevant consultant.
4. Management to closure — every issue has an owner, a status and documentation, until the model is clean.

When do you run the checks?

Not once at the end — in regular rounds throughout design: every model update cycle goes through detection, new issues enter management, and the trend is measured. The model converges gradually to zero open issues instead of one big "explosion" right before construction.

Frequently Asked Questions