Create a Breakdown Structure

Use the Breakdown Structure tools on the Home tab to create the spatial breakdown structures. All the spatial breakdown entities in the IFC-schema are modeled as tasks.

Find it here:

Note that not all sub menu choices are always active. This is because there are limitations below which spatial entity type in the structure breakdown tree the different spatial breakdown types can be placed. You need to select a correct parent spatial structure entity type in the Explorer to activate the menu choice you want to use. 

Learn more about Breakdown Structures and the IFC workflow here.