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Clash detection

Clash detection is the automated check for conflicts between building elements in a BIM model — typically across discipline models in a federation. It finds hard clashes, where geometry physically overlaps, and clearance (soft) clashes, where required space around an element is violated.

A duct routed through a steel beam is cheap to fix in a model and expensive to fix on site. Clash detection exists to move that discovery as early as possible: run the discipline models against each other, list every conflict, and resolve them while they are still design changes rather than rework orders.

How it works

Clash tests run on a federated model, checking element sets against each other — structure vs. ductwork, pipework vs. ceilings. Tools like Navisworks and ACC Model Coordination report each conflict with its location, the two elements involved, and a status as it moves through triage.

Frame glossary

Hard clash vs. clearance clash

Hard clash Clearance clash duct steel beam geometry overlaps steel beam pipe clearance zone intrudes required service space
A hard clash is physical overlap; a clearance (soft) clash violates required space around an element, even without contact.

Two kinds of clash matter in practice. A hard clash is physical overlap: two elements occupying the same space. A clearance clash (or soft clash) is a violated buffer: a pipe inside the access zone a beam connection needs, or equipment without its service clearance. Mature teams also track workflow around clashes — grouping thousands of raw results into meaningful issues, assigning owners, and watching counts trend down toward construction start.

Why it matters for BIM analytics

Raw clash results are a coordination artifact; the management questions live on top of them. How many open clashes per discipline pair? Which levels are converging and which are stuck? Is this week’s model better than last week’s?

That is a reporting problem, and it is exactly what Frame’s clash report templates are built for: clash tests from Navisworks or ACC become Power BI datasets, joined to element data and linked to the 3D viewer, so a coordination meeting can pivot from a trend chart to the actual clashing elements in one click.

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