BIM coordination exercises generate clash reports, no doubt, but most fail to eliminate construction risks. Projects are able to identify countless clashes during coordination reviews, however, unresolved issues still appear on-site as rework, installation delays, RFIs, and trade conflicts.
The software is not to be blamed for this mess. As a matter of fact, tools like Navisworks can efficiently detect model conflicts.
But the absence of a structured clash detection workflow that assigns responsibility, tracks revisions, and verifies closure before construction causes huge problems.
It’s important that an effective clash detection BIM workflow focuses on resolution management, and not on report generation alone.
Why Clash Detection Reports Alone do not Prevent Site Problems
Clash detection is often treated as a reporting activity. However, it should actually be considered as a risk management process.
A clash report is only able to identify where conflicts exist at a specific stage of design. It does not explain who owns the clash, which issues are serious enough to be resolved immediately, what revisions are required, if the clash affects fabrication or sequencing, and the right time to resolve the issue.
This can become a major issue especially in federated model clash detection MEP structural environments where multiple consultants and sub-contractors generate separate models.
The same clashes are more likely to appear repeatedly in coordination meetings without structured workflows, delaying approvals and increasing construction risk.
The Three Types of Clashes and Why They Require Different Resolution Approaches
Different types of clashes require different coordination responses, explained in the following table.
Clash Type | Example | Main Risk |
Hard clashes | Pipe intersecting beam | Physical installation impossible |
Soft clashes | Insufficient maintenance clearance | Access and operational issues |
Workflow clashes | Incorrect installation sequencing | Delays and rework |
Hard Clashes: Physical Intersections Between Elements that cannot Co-exist
Hard clashes are direct geometric conflicts, such as ducts intersecting structural beams or cable trays colliding with sprinkler systems.
Immediate redesign or rerouting is required in this case because these clashes make installation physically impossible. But every hard clash may not be equally bad.
Navisworks clash detection workflows use filtering and tolerance settings to help project teams prioritize constructability-critical issues over minor overlaps.
Soft Clashes: Clearance and Access Zone Violations that do not Show as Geometric Intersections
Soft clashes relate to operational or maintenance clearance issues instead of direct physical intersections.
Some examples may include inadequate service access, limited equipment maintenance space, and emergency clearance violations.
These clashes can create long-term operational problems despite geometry appearing conflict-free in the model.
Workflow Clashes: Sequencing and Phasing Conflicts that are Invisible to Geometrybased Detection
Workflow clashes are about sequencing and construction logistics, not related to geometry.
Some examples include equipment installed after structural closure, façade sequencing blocking crane access, and ceiling closures before testing activities.
These conflicts can generally be avoided through coordination between BIM teams and construction planners.
How to Structure a Clash Detection Workflow that Produces Resolutions not just Reports
The success of a BIM clash detection process depends on accountability and revision management.
An effective workflow should include discipline model submission, federated model coordination, clash testing and grouping, classification of severity, accountability assignment, regular coordination review meetings, revised model submissions, verification of clash closure, and sign-off approval.
Ownership assignment is the most important step. It’s essential for every clash to have a responsible discipline, target resolution date, and tracking status.
Projects should manage clashes through live dashboards, and not through static reports, in order to achieve faster resolution cycles and better coordination transparency.
Clash Severity Classification: How to Prioritize what gets Fixed First
Every clash does not require the same level of priority.
A structured clash resolution workflow should classify issues according to constructability impact, as shown in the following table.
Severity | Description | Action |
Critical | Stops construction or fabrication | Immediate redesign |
Major | Creates installation issues | Coordination revision |
Moderate | Minor routing conflict | Tray-level adjustment |
Low | Tolerance-related issue | Later-stage review |
It’s important for severity classification to consider construction sequencing, fabrication impact, procurement timelines, safety and access related risks, and operational requirements.
This process of classification helps project teams focus on clashes that create the highest project risks.
Discipline Responsibilities in the Clash Resolution Process
Coordination workflows are likely to fail if responsibilities remain unclear.
Who Owns the Clash: The Discipline that Caused it or the Discipline that must Move
Coordination hierarchy rules should be defined early in projects to avoid ambiguity.
A project team may, for example, decide that structural systems will be given priority over MEP routing, while another project may give priority to fixed equipment locations over surrounding services.
Some project management may choose to prioritize those architectural constraints control ceiling coordination.
Coordination meetings become repetitive negotiations without predefined rules.
How RFIs and Model Revisions are linked to the Clash Register
It’s important that each major clash connects directly to RFIs, model revisions, coordination comments, and approval records.
This process helps create traceability throughout the BIM coordination workflow.
Sign-off Process before the Coordination Model is marked Clash-free
Discipline teams should formally confirm before construction issues that all critical clashes are satisfactorily resolved, approved deviations are documented, clearance reviews are complete, and sequencing conflicts are also addressed.
Formal sign-off makes sure that unresolved coordination issues do not reach the site.
What a Clash-free Model Sign-off Package Should Contain Before Construction Issue
A proper sign-off package should include a final federated coordination model, a closed clash register, approved clash reports, sign-offs for each discipline, linked RFIs and revision history, and records of coordination meetings.
The objective of this documentation is to confirm that coordination risks were resolved before fabrication and installation activities began.
Conclusion
Clash detection software effectively identifies conflicts early enough, however, report generation itself is not adequate to prevent site problems.
Structured workflows that classify clashes, assign responsibilities, track revisions, and verify closure before construction begins, offer the real value of BIM coordination.
A clash detection BIM workflow must focus on resolution management, not just focusing on generating clash reports.
Work with Our Experts
The AEC Associates provides clash detection and BIM coordination services that go beyond report generation, every clash is classified, assigned, and tracked through to resolution.
- Reduce coordination-driven rework before construction starts.
- Improve multidisciplinary BIM coordination accuracy with structured support.
- Strengthen project delivery through efficient clash resolution workflows. Schedule a call today.
FAQ's
Clash detection identifies conflicts while clash resolution manages the process of assigning, revising, and closing those conflicts so that they do not reach the site.
Soft clashes affect maintenance access, safety clearances, and operational functionality even without geometric intersections.
A federated coordination model combines architectural, structural, MEP, and specialist trade models into a shared coordination environment.
