How to Perform Clash Detection in Revit

Edited 4 days ago by ExtremeHow Editorial Team

RevitClash DetectionBIMSoftwareQuality ControlArchitectureEngineeringConstructionWindowsCAD

In the field of Building Information Modeling (BIM), Revit stands out as a key tool that helps architects, engineers, and construction professionals work together effectively. One of the most important functions in this collaboration is clash detection. Clash detection is the process of identifying interference or collisions in a building model, such as when different components occupy the same space. Clash detection in Revit can help save time, reduce costs, and improve the overall quality of a construction project by identifying problems early in the design phase.

Why is collision detection important?

Before we dive into detail about how to detect clashes in Revit, let's understand why it is important. During construction, various building systems such as plumbing, electrical, HVAC, and structural elements must coexist within the same physical space. If clashes or conflicts between these systems are not noticed until construction, they can lead to costly rework and schedule delays. By detecting these clashes early in the design phase, stakeholders can mitigate risks, ensure smooth project execution, and increase collaboration between the various teams involved.

Basic concepts of collision detection

Collision detection involves checking the geometry of different building components to see if they interfere with each other. There can be different types of collisions, including:

• Hard collision: Direct physical overlap between components, such as the intersection of a beam with ductwork.
• Soft clash: Components impose certain spatial or clearance requirements that are not met by adjacent elements, such as maintenance access areas.
• 4D/Time Conflict: This occurs when the schedules of different tasks cause a conflict, such as two teams needing the same area to work at the same time.

Steps to perform clash detection in Revit

In Revit, the process of clash detection is often supported by other software designed specifically for clash analysis, such as Autodesk Navisworks. However, Revit itself has some basic tools that allow users to identify anomalies in the model. Here is a step-by-step guide on how to perform clash detection using Revit and common external platforms:

1. Preparation of the model

Before you begin clash detection, make sure your Revit model is well prepared. This should include consistent naming conventions for different elements, properly classified components, and accurate location of systems and structures. Make sure the model includes all the necessary components to provide a comprehensive analysis.

2. Using Revit's Coordinate Tools

Revit includes several built-in tools that assist with coordination and initial collision detection:

• Interference Checking: Within Revit, you can use the "Interference Checking" tool to compare different sets of elements within the model. This tool can help identify where components are in the same location. To perform an interference check:
  1. Go to the Collaboration tab.
  2. Select Interference Check, then Run Interference Check.
  3. Select the categories or groups of elements you want to check against each other.
  4. Review the list of potential conflicts identified by Revit and check each one.

3. Export to Navisworks for advanced clash detection

For more advanced clash detection capabilities, you can use Autodesk Navisworks. Navisworks allows users to aggregate models from multiple disciplines into a single environment for comprehensive clash detection analysis. To do this:

• Export your Revit model in a format compatible with Navisworks, usually as an NWC or NWD file.
• Import or add these exported files to the Navisworks model.
• Use Navisworks' collision detection tool to set up a collision test by selecting the elements or ranges to compare.

4. Setting up a clash test in Navisworks

Navisworks provides a powerful engine for defining and managing clash tests. To set up a clash test:

1. Open the Clash Detective tool in Navisworks.
2. Create a new clash test by specifying the selection sets or ranges to be tested against each other.
3. Customize parameters such as tolerance values to specify acceptable clearance levels between different elements.
4. Run a collision test to generate a report detailing the collisions identified.

5. Manage and resolve conflicts

After running a clash test, Navisworks provides detailed information about the detected clashes. The following steps can help manage and resolve these issues:

• Review collisions: Use Navisworks to review each collision individually. The software visualizes these collisions so users can understand where and why they occur.
• Assign responsibility: Conflicts should be classified based on discipline or responsibility. For example, conflicts involving structural and MEP elements can be assigned to the respective engineering teams for resolution.
• Coordination with teams: Use the findings from the conflict report to facilitate communication and coordination between the teams involved. Discuss possible solutions and approaches to resolve these conflicts.
• Update the model: Based on the identified solutions, update the Revit model accordingly. Make sure all modifications are synchronized in the model to prevent further conflicts.

6. Recheck and iterate

After resolving the identified conflicts, it is necessary to recheck to ensure that the applied solutions have effectively resolved the issues. If additional conflicts are identified, they should be addressed in subsequent iterations. Repeat this process until the desired level of model coordination is achieved.

Additional tips for effective collision detection

Here are some additional tips that can increase the efficiency and effectiveness of collision detection in Revit and Navisworks:

• Regular updates: Ensure that models from different disciplines are regularly updated and coordinated. This reduces the chance of conflicts and promotes streamlined model management.
• Use selection sets: Group similar objects or components into selection sets for targeted collision tests. This helps focus on potential problem areas without the distraction of irrelevant collisions.
• Maintain frequent communication: Open and frequent communication between all project stakeholders increases the chances of resolving disputes collaboratively and efficiently.
• Leverage BIM 360: Consider using a cloud-based platform like BIM 360 to facilitate real-time collaboration and model integration among dispersed teams.

Conclusion

Clash detection in Revit, combined with the advanced features of Autodesk Navisworks, plays a vital role in ensuring successful project outcomes in the construction industry. By proactively identifying and resolving clashes, BIM professionals can effectively minimize errors, reduce costs, and maintain the project schedule. When performed diligently as an iterative process, clash detection enables teams to deliver well-coordinated designs that meet the intended functional and aesthetic goals of a project. Ultimately, successful clash detection fosters a culture of collaboration and innovation, leading to structures that meet the highest standards of quality and efficiency.

Whether you're an architect, engineer, or construction manager, honing your clash detection skills in Revit is a valuable asset that not only enhances your technical capabilities but also contributes significantly to the overall success of your projects. By leveraging the capabilities of Revit and related tools, you can confidently navigate the complexities of modern building design and deliver striking results that leave a lasting impression.

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