How to fix this window issue with the subsurface modifer?

Support Modeling
1

I am modelling a toon building and when I apply subsurf modifier and make it smooth shading, I am getting this weird problem.

I think I might have extruded the window again which is causing this problem. How do I fix this?

I tried removing the face and recreating the face but it didn’t work.

Here are the screenshots and blend file

weird-window-problem.jpg1448×470 55.7 KB

2

Remove the extra Poly inside the window.

3

Recreate the face and extrude one time as another windows.

4

You have two extruded boxes in there with overlapping faces… delete the boxes’ faces, then join the other vertices back up with F.

http://i.imgbox.com/R7cDYc2f.png
R7cDYc2f.png774×638

http://i.imgbox.com/29tcZtjI.png
29tcZtjI.png667×609

5

Thanks everyone, got it fixed.

Actually I do not see any difference in flat shading but once I use free style, I get weird strokes and I realize I have double sides or have extruded one extra layer because a black stroke shows up on the model in those areas.