Happy Twenty 19 to all.
Version 6 SR12
The attached closed polysurface displays overhanging top and bottom surfaces on the inside of the curve in Shaded, Rendered, Ghosted, etc views. It looks OK in Wireframe, and ShowEdges exposes no stray edges.
I started with a polyline. From that, I created the outer vertical surface. I then created an offset curve from the initial curve, to use as the basis for the inner vertical surface. The top and bottom surfaces were created from the edges of the vertical surfaces, as were the end surfaces. At some point, I deleted the original polyline and the offset curve.
At that stage, I noticed the overhangs on the top and bottom surfaces, so I deleted the inner vertical surface and the top and bottom surfaces. I then recreated the inner vertical surface by sweeping the inner vertical edge of the far end surface along the lower edge of the outer vertical surface. The top and bottom surfaces were again created from the edges of the vertical surfaces. The overhang problem was the same.
Given that it is a closed polysurface, I cannot see why there is a rendered overhang.
HouseRemodelFStrayEdges.3dm (5.5 MB)