Trying to fix an issue with normals

I’m a noob at blender sorry.

https://drive.google.com/file/d/0BxO9BJYhQBeaN3NnV3ZTOVhZQjQ/view?usp=sharing

I want to know how to fix those lines artifacts on the 4 windows?

Thank you so much

I don’t think that’s a normal issue they all look to be pointing outwards assuming that’s where they are supposed to be pointing :slight_smile: it looks like the obj you have imported (guess) most likely had some sort of edge split applied when it was exported from whatever the original program was where it was created so the mesh is not actually joined to each other at those points it just looks like it is.

I think for the time you would spend trying to fix that because it’s all triangulated and out of alignment etc. you would be better off just remodelling it from scratch how you wanted it as they are simple shapes, that’s what I would do if someone handed me that file to work on.