Here is a script that converts a NURBS surface to a wall with components that can be exported to IFC. The wall is an Auto Hybrid object made up of 3D Solids that match the thicknesses and attributes of the components of a referenced wall style. CWS_1212_IFC.vwx
A couple caveats: Make sure that wall style names do not have a single or double quotation symbol in the name - it will get misinterpreted by the String Node. Also, if your base surface is an Interpolated Surface, use the tool in the 3D Power Pack - Rebuild NURBS... - to convert it to a standard NURBS surface.