About Linking to IFC Files

Link to an IFC file when you want to perform additional design work in Revit LT using the IFC file as a reference.

For example, another team designed the architectural model, and you link its IFC file so that you can design the interior.

You will not be able to make changes to the IFC model in Revit LT, but linking the IFC file allows you to see the model so you can continue the design work in Revit LT.

If you later change or update the original IFC file, the Revit model reflects the changes when you re-open it or reload the IFC file.

Accessing the IFC File in Revit

After you link an IFC file to the Revit model, the IFC file is listed in the following locations:

• Project Browser, Revit Links node
• Manage Links dialog, IFC tab
• Visibility/Graphic Overrides dialog, Revit Links tab

Referencing Elements in the IFC File

While linked IFC files are read-only in a Revit model, you can use them as references to do the following:

• Dimension to references of IFC elements. (These references apply to the faces of linked IFC geometry and not to center lines, reference planes, or other non-geometry elements.)
• Snap to IFC-based elements.
• Align Revit elements to IFC-based elements.
• Host some face-based families, such as conduit and some electrical devices. (This hosting does not include wall, roof, or floor-specific hosted families. For example, you cannot insert a door or a window into a linked IFC wall.)
• Tag the IFC elements. See Tagging Elements in Linked Models.

If the IFC file changes and you reload it into the Revit model, verify previously established references. Some changes to IFC geometry may make it difficult to maintain references in the Revit model.

Defining Room Boundaries with IFC-Based Elements

When creating rooms in the host model, you can use many IFC-based elements to define room boundaries, including walls, roofs, floors, ceilings, columns, doors, and windows. IFC-based walls use the wall finish face as the room boundary.

Note: You cannot use IFC-based curtain elements to define rooms. If needed, add room separation lines along the boundaries of curtain elements. See Add a Room Separation Line.

When you link an IFC file, by default its Room Bounding property is turned off. To enable room bounding for all elements in the IFC file that support it, see Use Room Boundaries in a Linked Model.

Phases for IFC-Based Elements

When you link an IFC file, its elements are assigned to a default construction phase in the Revit model. That phase is used for the Phase Created property of the elements in the linked IFC file.

Specifically, the assigned phase is determined by the template used during the IFC Import/Link operation. See Select a Template for IFC Files.

Updating the IFC File

When updating a Revit model with an IFC link, Revit LT proceeds as follows:

1. Revit LT checks the timestamp and size of the IFC file.
2. If the current file has a newer timestamp or different file size, Revit LT uses the IFC GUIDs to match entities in the IFC file with elements in the Revit model.
3. Based on this information, Revit LT adds new elements and updates existing elements, and deletes elements that are no longer in the IFC file.

Note: During this process, Revit LT uses the IFC file to create an intermediate IFC-based model. Do not attempt to directly modify the intermediate IFC-based model. If you do so, you may no longer be able to update the Revit model with changes to the original IFC file.