Interference Checking

Locate invalid intersections between elements in a model.

The Interference Check tool can find intersections among a set of selected elements or all elements in the model.

Typical Workflow for Interference Checking

This tool can be used during the design process to coordinate major building elements and systems. Use it to prevent conflicts and reduce the risk of construction changes and cost overruns.

The following is a common workflow:

• An architect meets with a client and creates a basic model.
• The building model is sent to a team that includes members from other disciplines, such as structural engineers. They work on their own version of the model. Then the architect links it in and checks for interferences.
• Team members from other disciplines return the model to the architect.
• The architect runs the Interference Check tool on the existing model.
• A report is generated from the interference check, and undesired intersections are noted.
• The design team discusses the interferences and creates a strategy to address them.
• One or more team members are assigned to fix any conflicts.

Elements Requiring Interference Checking

Some examples of elements that could be checked for interference include the following:

• Structural girders and purlins
• Structural columns and architectural columns
• Structural braces and walls
• Structural braces, doors, and windows
• Roofs and floors
• Specialty equipment and floors
• A linked Revit model and elements in the current model

For a complete list of all categories eligible for interference checking see: Interference Checking Categories.

Note: MEP fabrication parts and detailed steel modeling elements are not included during interference checking. The recommended workflow is to use Navisworks.

To run an interference check

1. If desired, select some elements in a view.
2. Click Collaborate tabCoordinate panelInterference Check drop-down (Run Interference Check).

   The Interference Check dialog opens.

   If you selected elements in the view, the dialog is filtered to display only those element categories.

   If you did not select any elements, the dialog displays all categories from the current model.

3. On the left side of the dialog, select a value from the first Categories from drop-down.

   For example, select Current Project.

   Note: If you selected a linked Revit model to run a check, you must select its name from this option. For example, if you selected the linked model called Mylink1, select that name from Categories from drop-down. After you select the name, element categories in the linked model are listed.
4. Select the desired categories.

   For example, select Roofs as the category.

5. On the right side of the dialog, select a value from the second Categories from drop-down.

   This value could be a current selection of elements, the current model, or a linked Revit model.

6. Select the other desired categories.

   For example, to complete a roof-floor interference check, select floors as the category.

7. Click OK.

   If no interferences are discovered, a dialog displays informing you of this.

   If interferences are discovered, the Interference Report dialog displays. The dialog lists all elements that are in conflict with one another.

   Interferences are grouped according to the way you generated the check. By default, they are grouped as Category 1 (left category column) and Category 2 (right category column). You can change this grouping to Category 2, Category 1. For example, if you ran the roof and floor check, the dialog would list the roof category first, and then which floors are intersecting the roof.

8. To see one of the elements that is intersected, select its name in the Interference Report dialog, and click Show.

   The current view displays the problem.

9. To correct a conflict, click in the view and modify the overlapping elements.

   The Interference Report dialog remains visible.

10. When you have fixed the problem intersection, in the Interference Report dialog, click Refresh.

    If the problem has been resolved, the problem elements are removed from the list of conflicts.

    Note: Refresh rechecks only those interferences in the current report. It does not rerun the interference check.

    You can continue resolving conflicts in this manner.

    If you cannot resolve all conflicts without additional input from team members, you can generate an HTML version of the report.

11. In the Interference Report dialog, click Export.
12. Enter a name, navigate to the desired folder to save the report, and click Save.
13. In the Interference Report dialog, click Close.
14. To see the last report generated again, click Collaborate tabCoordinate panelInterference Check drop-down (Show Last Report).

    This tool does not rerun the interference check.

Interference Check Tips

• Processing time for interference checks can vary greatly. In a large model, checking all categories against each other can take a long time and is not recommended. To reduce processing time, select a limited set of elements or a limited number of categories.
• To run a check on all available categories, click All in the Interference Check dialog, and then select one of the check boxes next to a category.
• Click None to clear the selection of any categories.
• Click Invert to change the selection between categories that are currently selected and those that are not.