https://community.graphisoft.com/t5/Collaboration-with-other/Roofs-appear-as-quot-IfcSlab-quot-after-export-to-IFCxml/m-p/201579#M25049 Check the Element Classification Field for the Roofs. They may be set to "Slab" and this is why it is exported as Slab to IFC.<BR /> YOu can specifically set this field to Roof and then it should export them as IFCRoof.<BR /><IMG src="https://community.graphisoft.com/t5/image/serverpage/image-id/11085i087AB40AA5FA68B0/image-size/large?v=v2&amp;px=999" border="0" alt="RooftoIFCRoof.png" title="RooftoIFCRoof.png" /> Mon, 08 Oct 2012 09:41:30 GMT Laszlo Nagy 2012-10-08T09:41:30Z https://community.graphisoft.com/t5/Collaboration-with-other/Roofs-appear-as-quot-IfcSlab-quot-after-export-to-IFCxml/m-p/201578#M25048 <DIV class="actalk-migrated-content"><T>Hi to All, <BR /> <BR /> I use ArchiCAD 15 and when I export a model of a 2-floors building with <BR /> standart Roof (45 degrees, 4-sided) , when I export this model to IFCxml file format, the roof is exported as Slab.<BR /> <BR /> Instead of exporting it as IfcRoof ArchiCAD exports it as IfcSlab, and this way important Info as Roof's Offset, Height and Angle are lost. <BR /> <BR /> Why this Bug happens? <BR /> <BR /> Is there a workaround ?</T></DIV> Mon, 08 Oct 2012 09:25:31 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Roofs-appear-as-quot-IfcSlab-quot-after-export-to-IFCxml/m-p/201578#M25048 Anonymous 2012-10-08T09:25:31Z https://community.graphisoft.com/t5/Collaboration-with-other/Roofs-appear-as-quot-IfcSlab-quot-after-export-to-IFCxml/m-p/201579#M25049 Check the Element Classification Field for the Roofs. They may be set to "Slab" and this is why it is exported as Slab to IFC.<BR /> YOu can specifically set this field to Roof and then it should export them as IFCRoof.<BR /><IMG src="https://community.graphisoft.com/t5/image/serverpage/image-id/11085i087AB40AA5FA68B0/image-size/large?v=v2&amp;px=999" border="0" alt="RooftoIFCRoof.png" title="RooftoIFCRoof.png" /> Mon, 08 Oct 2012 09:41:30 GMT https://community.graphisoft.com/t5/Collaboration-with-other/Roofs-appear-as-quot-IfcSlab-quot-after-export-to-IFCxml/m-p/201579#M25049 Laszlo Nagy 2012-10-08T09:41:30Z