By Dennis Collin
I have recently had several discussions on Revit and best practice to get IFC data into a model. This process seems to be hit or miss for many users.
For example, if a user opens an IFC file directly within Revit, the components may be categorised correctly, but they are all in-place families. In-place families are not ideal in Revit as they cannot be moved or changed like regular component families. This may not be an issue for elements that represent existing structures or site components, but for users working within MEP disciplines this could be problematic.
This situation will happen with elements that have been created in 3rd party products or newer versions of Revit, and then exported out to IFC. The IFC format has different schemas for ifcPipe, ifcPipeFittings, ifcduct and ifcductfittings etc. and Revit if configured correctly, should import them to the correct category. The Export mappings need to be done in the originating application to that the IFC class name is correctly set for each component type.
An example from Revit’s IFC Export function is shown below:
If the mappings have been set correctly, these elements can be viewed within Revit and when selected will show the correct category in the Properties Palette.
However, when inspecting elements, the Type selector dropdown menu is blank making it difficult to change a component. Also, many of the expected parameters do not seem to make the transfer trip to Revit from the original application.
An easy workaround to this problem is to LINK the IFC file into a suitable blank Revit project template.
Once linked, perform a visual inspection to ensure that the geometry shows as expected. Then select the linked file and bind it. Depending on the file size this may take some time!
The Bind process will convert the various elements to Direct Shape objects which behave more like native Revit System and component families. This linking method uses the newer Direct Shape API, whereas the opening method uses an older method of reading IFC data. The newer method means that elements are more changeable and more familiar looking in terms of parameters etc. Also, more parameters seem to be imported as well making this somewhat unorthodox method of accessing IFC data compelling.
Although these objects won’t be editable like regular component and system families, the elements should show and display the relevant data from the original application and be swappable for other elements of a similar type.
TIP. For large scale projects the IFC files may be large in file size. To mitigate lengthy linking and binding processes, consider splitting the model into smaller more manageable chunks and only include necessary parameter information. Consider the enabling the export of only elements visible in View and keep the level of detail to ‘Low’.
If problems persist, update the IFC file add-ins, not just for Revit but also for the authoring application, this can have a substantial impact on file size, IFC format versions and a successful transfer outcome. The IFC Add in is a free download from the Autodesk App store and the improved IFC add-in is usually released around 6 months after each Revit version’s initial release date.