Stretched textures in Blender

Question

First of all: I'm relatively new to Blender.

I discovered a weird bug in Blender 2.78c. On my object some textures are stretched although they are UV mapped. Since I have no clue why this is happening I took some screenshots which hopefully explain the problem.

I tried various things, but found no way to solve this. Things I tried:

• Unwrap again
• Apply Rotation and scale
• Manually adjusting verts in UV map
• Looking for "dead" verts somewhere in the model

Does anyone know this strange behavior?

Edit: I uploaded my .blend file -> http://pasteall.org/blend/index.php?id=47124 | merged screenshots due to low reputation :P

Answer 1

The issue is bad UV unwrapping from the ngons in your mesh. What you have are vertices in the middle of the corner edge that have unwrapped to be close to the outer corner vertex in the uvmap. This leads to the small section of the image stretching to fill the face between the two vertices.

The simplest fix would be to remove the extra vertices. In vertex select mode select them and press X->Dissolve Vertices

If you needed to keep the ngons, you can get a flat view of the wall in the 3d view (using left/front views would be the easiest) and use U->Project from View