The first in a short series of posts explaining the settings when exporting from Revit to IFC.
IFC EXPORT AS
Setting up a model and exporting to IFC has been better integrated in Revit 2023 & 2024. In versions prior to Revit 2023 the mapping process requires the inclusion of specialist parameters to overcome problems where category mapping is not suitable.
Take, for example, a common situation where floor finishes have been modelled separately as individual floor elements. These should not convert to IfcSlab, but IfcCovering. Of course, it isn’t correct to map all Floors to IfcCovering in the IFC Export Classes options (File > Export > Options > IFC Options).
Instead, there are built-in parameters introduced in Revit 2023 that can set the IFC mapping for a specific type, or instance.
Export Type to IFC Defines whether the Type is exported to IFC or not. Setting this to Default uses the settings in Category mapping. To always export this type, regardless of the category mapping, select Yes. To never export this type, select No.
This will be picked up in more detail in the next blog post.
Export Type to IFC As An improved dialog-based selection of the IfcType and Predefined Type to use. You’ve still got to know which IfcType is correct, but selection if from a list, with search capabilities.
Pick the correct Type and Predefined Type (if needed). In the case of floor finishes, the selection would be as shown below:
Note: Make sure to choose the correct IFC Schema version at the top of the dialog first. Your project information standard should tell you which to use. If not, the most widely used is still IFC2X3.
This type will now export correctly as IfcCovering, and all other floors will remain IfcSlabs.
ENTITIES TO EXPORT
Another very helpful addition is the check list of entities to export. This can be used in addition to, or instead of, Category mapping.
In the IFC Setup, under the Advanced tab, there is an Entities to Export button which opens a list of entities. Tick the entities needed; untick those that should not be exported.
This is saved as part of the setup, so standard lists can be saved and imported.
Note: do NOT untick IfcSite as this will remove the top-level site from the exported IFC model, rending its structure incorrect. (A floor exists within a building; a building exists within a site; a site exists within a model.) Instead, set the Site Category correctly which will be covered next time.