My neighbour has recently built an extension on the back of his house (I am in a semi-detached) and the roof of it overhangs the brickwork by about 2", this falling onto the boundary line between the two houses. He then put up a new fence (the old half tumbled down eyesore had been there for about 3 years). The thing is, the fence has been built on MY property. What I need to know is (bearing in mind it has taken so long for him to replace the eyesore that was there).. will he have to take it down and move it if I ask (for example, if i want an extension building onto my house)? The other thing is, although it is on his property by 2", his extension has a vent (cooker maybe?), If I build an extention, and steam/damp comes out of this vent onto the wall of my extention, can he be forced to block it off?