If you want to work with IFC, use Blender and the Bonsai addon. It adds native IFC to Blender. I've moved away from SH3D because for my purposes Bonsai works better for me. The only caveat is that it is still a work-in-progress, so it can be tough to get to grips with.
Trying to add IFC to SH3D would be like mixing oil and water - they do things in very different ways.