The Building Materials dialog box has a new “Participates in Collision Detection” checkbox in the Categories and Properties section. (This is useful for defining whether particular building components – parts of composite or complex elements – should be exported in IFC, and/or whether they should participate in collision detection when viewed in MEP applications.)
All Building Materials are migrated with the checkbox ON. (By default, all migrated Building Materials are set to participate in Collision Detection.) To exempt any Building Material, uncheck its box in the Building Materials dialog box.