Maz,

I knew I had forgotten something: textures.

It's a long known problem that some models from the Sketchup website cause problems when rendering in SH3D. There has been a nice exchange on the forum on that issue as well.

There is a not too complex solution, namely to apply the texture to both sides of the affected faces. And if I can do that in Sketchup, than everybody can.

Also, under Options you should set the export settings to double faced.

H