I have a strange problem. I modeled and textured some plane using UV mapping which I modified and extruded a lot. Now when I render it from different angles, I have transparent meshes in different sides of the model.
When I do Mesh > Flip Normals, it flipped all the faces which previous looking transparent and now they look textured.
So how I make my mesh consistent and without transparent faces?
Here is the images after flipping normals:
And this is after: see the back of the model now is transparent


Ctrl+N(with all selected) ? This should make them facing the same direction regardless how they were directed before. If this doesn't help I'm afraid you'll need to flip individual normals by hand. – Mr Zak Feb 11 '16 at 12:03