You need to respond to a served notice from neighbor who wants to do works to their property such as but not limited to:
Raising or demolishing a Party wall or fence
If they are cutting into the party wall to place a beam (as in Loft conversion)
Inserting a damp proof course, even at their side of party wall
Raising a party wall and need to cut or repair some parts
Underpinning the party wall
Weathering the building either side or on the line of boundary
Excavating within 3 meters of your structure to the depth lower than your foundation
Excavating within 6 meters of your structure to a depth below the line of 45 degrees drawn from bottom of your foundation.