I think we've been around the houses on this issue before, but want to make sure I'm not missing something, because it causes me endless trouble.
All this is, is a wall, with a top section formed of two directly modelled solids. The wall and the two top pieces are all finished in the same material, and where their surfaces join each other they are coplanar. So, when I generate elevations from the model, there should not be any lines between them. But there are, and as far as I know t