Neighbour smells

Hang cow manure out the window and dangle it just above his window. Tell him you will remove it when he fixes the stink from his place first!

 

Who is responsible for the overall structure of the building ?

 

If you can see where the vent is on outside wall and 'if' you know the layout of their kitchen ? Then you can possibly lift some floorboards as suggested to uncover fan duct

Not always easy though getting at floorboards - laminate floor / carpets to remove, then may be chipboard sheeting not floorboards

Not as easy as seems unfortunately

 

Thats a great idea, a bit like a time at work once. We had a smelly employee. The boss left a can off Lynx on his bench. Straight to the point works best.

 

Hi my downstairs neighbors toilet stinks is there any plastic window ledges long enough and wide enough and easily fixed to use as an external window ledge?

 

That is a brilliant question and certainly got me interested in how the two go together.
More info needed but looks likely to be an interesting, and possibly amusing discussion.