This is a proof of concept Blender add-on that mashes the Molior IFC generator from the Homemaker project, Blenderbim, and some clever non-manifold geometry ideas borrowed from Topologic.
https://www.youtube.com/watch?v=bM4ewlvLJ98
@frankiezafe I don't have the code (yet) to fit a pitched roof against a side wall, so it draws a flat roof with parapets
@brunopostle cool! I didn't get the condition to make a roof or a platform... Is it linked to the fact that there is a connection with a wall?